Optimum BMI?

A place to get your questions answered from McDougall staff dietitian, Jeff Novick, MS, RDN.

Moderators: JeffN, carolve, Heather McDougall

Re: Optimum BMI?

Postby JeffN » Thu Mar 26, 2015 9:39 am

"In obese adults, intentional weight loss may be associated with approximately a 15% reduction in all-cause mortality."


Intentional weight loss and all-cause mortality: a meta-analysis of randomized clinical trials.
Kritchevsky SB, Beavers KM, Miller ME, Shea MK, Houston DK, Kitzman DW, Nicklas BJ.
PLoS One. 2015 Mar 20;10(3):e0121993. doi: 10.1371/journal.pone.0121993. eCollection 2015.
PMID:25794148[PubMed - in process] Free Article
http://journals.plos.org/plosone/articl ... ne.0121993
http://www.plosone.org/article/fetchObj ... tation=PDF

Abstract

BACKGROUND: Obesity is associated with increased mortality, and weight loss trials show rapid improvement in many mortality risk factors. Yet, observational studies typically associate weight loss with higher mortality risk. The purpose of this meta-analysis of randomized controlled trials (RCTs) of weight loss was to clarify the effects of intentional weight loss on mortality.

METHODS: 2,484 abstracts were identified and reviewed in PUBMED, yielding 15 RCTs reporting (1) randomization to weight loss or non-weight loss arms, (2) duration of =/>18 months, and (3) deaths by intervention arm. Weight loss interventions were all lifestyle-based. Relative risks (RR) and 95% confidence intervals (95% CI) were estimated for each trial. For trials reporting at least one death (n = 12), a summary estimate was calculated using the Mantel-Haenszel method. Sensitivity analysis using sparse data methods included remaining trials.

RESULTS: Trials enrolled 17,186 participants (53% female, mean age at randomization = 52 years). Mean body mass indices ranged from 30-46 kg/m2, follow-up times ranged from 18 months to 12.6 years (mean: 27 months), and average weight loss in reported trials was 5.5±4.0 kg. A total of 264 deaths were reported in weight loss groups and 310 in non-weight loss groups. The weight loss groups experienced a 15% lower all-cause mortality risk (RR = 0.85; 95% CI: 0.73-1.00). There was no evidence for heterogeneity of effect (Cochran's Q = 5.59 (11 d.f.; p = 0.90); I2 = 0). Results were similar in trials with a mean age at randomization =/>55 years (RR = 0.84; 95% CI 0.71-0.99) and a follow-up time of =/>4 years (RR = 0.85; 95% CI 0.72-1.00).

CONCLUSIONS: In obese adults, intentional weight loss may be associated with approximately a 15% reduction in all-cause mortality.
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Re: Optimum BMI?

Postby JeffN » Fri Apr 10, 2015 3:57 pm

In regard to the study today saying being a little overweight is better in regard to dementia...

From a leading longevity researchers comments on the study..

"This is an epidemiological artifiact as the one with BMI and mortality. How many people in UK older than 55 have a BMI lower than 20 because they are eating healthy moderatly restricted diets, exercise and not smoke ? Probably 1 or 2 every 1000 if we are lucky. This study is simply showing that people who are lean because of chronic underlying condition or malnutrition which make them lose weight are at higher risk of dementia."

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Re: Optimum BMI?

Postby JeffN » Sun May 24, 2015 1:50 pm

The impact of obesity on prostate cancer recurrence observed after exclusion of diabetics.
Cancer Causes Control. 2015 Jun;26(6):821-30. doi: 10.1007/s10552-015-0554-z. Epub 2015 Mar 14. PMID: 25771797

http://www.ncbi.nlm.nih.gov/m/pubmed/25771797/

Abstract

Purpose
Although overall there is a positive association between obesity and risk of prostate cancer (PrCa) recurrence, results of individual studies are somewhat inconsistent. We investigated whether the failure to exclude diabetics in prior studies could have increased the likelihood of conflicting results.

Methods
A total of 610 PrCa patients who underwent radical prostatectomy between 2005 and 2012 were followed for recurrence, defined as a rise in serum PSA ≥ 0.2 ng/ml following surgery. Body mass index (BMI) and history of type 2 diabetes were documented prior to PrCa surgery. The analysis was conducted using Cox proportional hazard models.

Results
Obesity (25.6 %) and diabetes (18.7 %) were common in this cohort. There were 87 (14.3 %) recurrence events during a median follow-up of 30.8 months after surgery among the 610 patients. When analyzed among all PrCa patients, no association was observed between BMI/obesity and PrCa recurrence. However, when analysis was limited to non-diabetics, obese men had a 2.27-fold increased risk (95 % CI 1.17–4.41) of PrCa recurrence relative to normal weight men, after adjusting for age and clinical/pathological tumor characteristics.

Conclusions
This study found a greater than twofold association between obesity/BMI and PrCa recurrence in non-diabetics. We anticipated these results because the relationship between BMI/obesity and the biologic factors that may underlie the PrCa recurrence–BMI/obesity association, such as insulin, may be altered by the use of anti-diabetes medication or diminished beta-cell insulin production in advanced diabetes. Studies to further assess the molecular factors that explain the BMI/obesity–PrCa recurrence relationship are warranted.
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Re: Optimum BMI?

Postby JeffN » Tue Aug 11, 2015 1:53 pm

For those interested in the issues of weight management and obesity, this is an amazing read. It is written by one of the centuries leading researchers in the field. I was fortunate to visit him while he was at the Pennington Research Center and see the metabolic testing ward.

Why Obesity?
Annu. Rev. Nutr. 2015. 35:1–31
George A. Bray
Pennington Biomedical Research Center,
Louisiana State University,
Baton Rouge, Louisiana 70808;

Full Text
http://www.annualreviews.org/doi/pdf/10 ... 214-104412

Abstract
As Erwin Chargaff observed, “Scientific autobiography belongs to a most awkward literary genre,” and mine is no exception. In reviewing my scientific life, I contrast the nutritional influences that would have existed had I been born 100 or 200 years earlier than I actually was. With this background, I trace the influences on my formative years in science beginning in high school and ending as a postdoctoral fellow in Professor E.B. Astwood’s laboratory, when my directional sails were set and obesity was the compass heading. With this heading, the need for organized national and international meetings on obesity and the need for a scientific journal dealing with obesity as its subject matter became evident and occupied considerable energy over the next 30 years. The next section of this memoir traces the wanderings of an itinerant academic who moved from Boston to Los Angeles and finally to Baton Rouge. The influence of Sir William Osler’s idea that there is a time for education, a time for scholarship, a time for teaching, and time to retire has always been a guide to allocating time ever since I was an intern at Johns Hopkins Hospital. It was in Baton Rouge that the final phase began: I agreed to become the first full-time executive director of the Pennington Biomedical Research Center, a decision that changed my life. The article ends with a quotation from Tennessee Williams that reflects the theater, which has given me so much pleasure over the years: “There is a time for departure even when there’s no certain place to go.”
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Re: Optimum BMI?

Postby JeffN » Sun Oct 04, 2015 7:31 am

Excellent discussion in the CRSociety forums about BMI and why some studies show lower BMI is not the best, especially this point from a study quoted..

"Approximately 9 years before death, the rate of weight loss increased to an average of 0.39 kg/year (P < 0.001) for all-cause mortality. For cancer deaths, weight loss accelerated significantly 3 years before death, regardless of age group. For cardiovascular deaths, the best-fitting inflection point increased with age, from 5 years for participants aged 60–69 years to 9–10 years before death for those aged 80 years or older. Results suggest that weight loss in older persons may begin earlier than previously believed. The duration of weight loss for noncancer deaths suggests that even distal changes in energy balance may be linked to risk of death."

and these comments..

"Nearly no epidemiological studies on body weight/BMI have even run for long enough to account for a 9 year trajectory of disease-related weight loss. Most such studies either fail to exclude any early deaths that are likely related to undiagnosed disease onset, or exclude no more than 3 years of such deaths (I have never seen more than 5 years excluded)."

https://www.crsociety.org/topic/11129-r ... longevity/

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Re: Optimum BMI?

Postby JeffN » Wed Oct 21, 2015 1:45 pm

Association of Total Energy Intake with 29-Year Mortality in the Japanese: NIPPON DATA80.
J Atheroscler Thromb. 2015 Oct 13. [Epub ahead of print]

Abstract

AIM:
In animals, dietary energy restriction is reported to increase longevity, whereas in humans, all cohort studies from Western countries have not shown an association between the low energy intake and longevity. We examined the association between total energy intake and longevity in Japan where dietary pattern is different from that in the West.

METHODS:
A total of 7,704 Japanese aged 30-69 years were followed from 1980 to 2009. Participants were divided into the quintiles of total energy (kcal/day) based on data collected from the National Nutrition Survey. Hazard ratios and 95% confidence intervals (CIs) were derived through the use of Cox proportional hazards models to compare the risk of death across and between the quintiles.

RESULTS:
There was a significant association between increased energy intake and all-cause mortality risk in only men (P for linear trend=0.008). In cause-specific analysis, compared with the lowest quintile, there was rise in coronary heart disease (CHD) mortality among men (HR; 2.63, 95%CI; 0.95-7.28, P fro linear trend 0.016) and women (HR; 2.91, 95%CI; 1.02-8.29, P for linear trend 0.032) and cancer mortality among men (HR; 1.50, 95%CI; 0.999-2.24, P for linear trend 0.038) in the top quintile.

CONCLUSION:
We observed significant associations of high energy intake with all-cause and cancer mortality among men and with CHD mortality among men and women. Further studies are needed to confirm the benefits of caloric restriction.
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Re: Optimum BMI?

Postby JeffN » Sun Oct 25, 2015 8:43 am

Six-month Calorie Restriction in Overweight Individuals Elicits Transcriptomic Response in Subcutaneous Adipose Tissue That is Distinct From Effects of Energy Deficit.
Lam YY, Ghosh S, Civitarese AE, Ravussin E.
J Gerontol A Biol Sci Med Sci. 2015 Oct 20. pii: glv194. [Epub ahead of print]
PMID: 26486851

http://biomedgerontology.oxfordjournals ... hort?rss=1

Abstract

Calorie restriction confers health benefits distinct from energy deficit by exercise. We characterized the adipose-transcriptome to investigate the molecular basis of the differential phenotypic responses. Abdominal subcutaneous fat was collected from 24 overweight participants randomized in three groups (N = 8/group): weight maintenance (control), 25% energy deficit by calorie restriction alone (CR), and 25% energy deficit by calorie restriction with structured exercise (CREX). Within each group, gene expression was compared between 6 months and baseline with cutoffs at nominal p </= .01 and absolute fold-change =/> 1.5. Gene-set enrichment analysis (false discovery rate < 5%) was used to identify significantly regulated biological pathways. CR and CREX elicited similar overall clinical response to energy deficit and a comparable reduction in gene transcription specific to oxidative phosphorylation and proteasome function. CR vastly outweighed CREX in the number of differentially regulated genes (88 vs 39) and pathways (28 vs 6). CR specifically downregulated the chemokine signaling-related pathways. Among the CR-regulated genes, 27 functioned as transcription/translation regulators (eg, mRNA processing or transcription/translation initiation), whereas CREX regulated only one gene in this category. Our data suggest that CR has a broader effect on the transcriptome compared with CREX which may mediate its specific impact on delaying primary aging.
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Re: Optimum BMI?

Postby JeffN » Mon Dec 21, 2015 10:35 am

Abstract

Aerobic fitness in late adolescence and the risk of early death: a prospective cohort study of 1.3 million Swedish men
Int. J. Epidemiol. (2015) doi: 10.1093/ije/dyv321

http://m.ije.oxfordjournals.org/content ... 359054bcdf

Background: Fitness level and obesity have been associated with death in older populations. We investigated the relationship between aerobic fitness in late adolescence and early death, and whether a high fitness level can compensate the risk of being obese.

Methods: The cohort comprised 1 317 713 Swedish men (mean age, 18 years) that conscripted between 1969 and 1996. Aerobic fitness was assessed by an electrically braked cycle test. All-cause and specific causes of death were tracked using national registers. Multivariable adjusted associations were tested using Cox regression models.

Results: During a mean follow-up period of 29 years, 44 301 subjects died. Individuals in the highest fifth of aerobic fitness were at lower risk of death from any cause [hazard ratio (HR), 0.49; 95% confidence interval (CI), 0.47–0.51] in comparison with individuals in the lowest fifth, with the strongest association seen for death related to alcohol and narcotics abuse (HR, 0.20; 95% CI, 0.15–0.26). Similar risks were found for weight-adjusted aerobic fitness. Aerobic fitness was associated with a reduced risk of death from any cause in normal-weight and overweight individuals, whereas the benefits were reduced in obese individuals (P < 0.001 for interaction). Furthermore, unfit normal-weight individuals had 30% lower risk of death from any cause (HR, 0.70; 95% CI, 0.53–0.92) than did fit obese individuals.

Conclusions: Low aerobic fitness in late adolescence is associated with an increased risk of early death. Furthermore, the risk of early death was higher in fit obese individuals than in unfit normal-weight individuals.



Mass Media Article

No, you CAN'T be fat and fit, say the experts: Doing lots of exercise while overweight 'does not prevent an early death'

http://www.dailymail.co.uk/health/artic ... death.html
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Re: Optimum BMI?

Postby JeffN » Tue Jan 05, 2016 7:40 am

"Our results suggest the burden of overweight and obesity on mortality is likely substantially larger than commonly appreciated. If correct, this may have serious implications for the future of life expectancy in the United States."

Revealing the burden of obesity using weight histories
PNAS
Proceedings of the National Academy of Sciences
Early Edition
Andrew Stokes,
doi: 10.1073/pnas.1515472113

Full Text
http://www.pnas.org/content/early/2016/ ... 3.full.pdf

Significance

There is substantial uncertainty about the association between obesity and mortality. A major issue is the treatment of reverse causation, a phrase referring to the loss of weight among people who become ill. Weight histories are vital to addressing reverse causality, but few studies incorporate them. Here we introduce nationally representative data on lifetime maximum weight to distinguish individuals who were never obese from those who were formerly obese and lost weight. We formally investigate the performance of various models, finding that models that incorporate history perform better than the conventional approach based on a single observation of weight at the time of survey. We conclude that the burden of obesity is likely to be greater than is commonly appreciated.

Abstract

Analyses of the relation between obesity and mortality typically evaluate risk with respect to weight recorded at a single point in time. As a consequence, there is generally no distinction made between nonobese individuals who were never obese and nonobese individuals who were formerly obese and lost weight. We introduce additional data on an individual’s maximum attained weight and investigate four models that represent different combinations of weight at survey and maximum weight. We use data from the 1988–2010 National Health and Nutrition Examination Survey, linked to death records through 2011, to estimate parameters of these models. We find that the most successful models use data on maximum weight, and the worst-performing model uses only data on weight at survey. We show that the disparity in predictive power between these models is related to exceptionally high mortality among those who have lost weight, with the normal-weight category being particularly susceptible to distortions arising from weight loss. These distortions make overweight and obesity appear less harmful by obscuring the benefits of remaining never obese. Because most previous studies are based on body mass index at survey, it is likely that the effects of excess weight on US mortality have been consistently underestimated.

From The Discussion

"Our results suggest the burden of overweight and obesity on mortality is likely substantially larger than commonly appreciated. If correct, this may have serious implications for the future of life expectancy in the United States. Although the prevalence of obesity may level off or even decline, the history of rapidly rising obesity in the last 3 decades cannot be readily erased (63). Successive birth cohorts embody heavier and heavier obesity histories, regardless of current levels. Those histories are likely toexert upward pressure on US mortality levels for many years to come."
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Re: Optimum BMI?

Postby JeffN » Tue May 10, 2016 2:08 pm

Body mass index and mortality: understanding the patterns and paradoxes.
Wild SH, Byrne CD.
BMJ. 2016 May 4;353:i2433. doi: 10.1136/bmj.i2433. No abstract available.
PMID: 27146663
http://www.bmj.com/content/353/bmj.i2433

People who are lean for life have the lowest mortality

The optimal body mass index (BMI) associated with lowest risk of all cause mortality is not known. As excess adiposity increases risk of conditions such as diabetes that reduce life expectancy, one might expect increasing BMI to be associated with increasing mortality. However, compared with normal weight, underweight is associated with increased mortality and modestly elevated BMI is associated with lower mortality. The former pattern is only partly explained by confounding by smoking or comorbidity, and the second observation has been called the obesity paradox.1 In addition, the influence on mortality of different patterns of weight change throughout the life course is poorly understood. Two linked papers attempt to shed light on these important subjects.2 3

Aune and colleagues (doi:10.1136/bmj.i1256) report a meta-analysis of 230 prospective studies with more than 3.74 million deaths among more than 30.3 million participants, providing further evidence that adiposity (measured by BMI) increases the risk of premature death.2 Some increase in risk was observed in lower weight participants, and in the analysis of all participants the lowest mortality was observed with a BMI of around 25. However, the lowest mortality was observed in the BMI range 23-24 among never smokers, in the BMI range 22-23 among healthy never smokers, and in the BMI range 20-22 among studies of never smokers with longer durations of follow-up (=/>20 and =/>25 years). The findings show the importance of smoking and comorbidity in confounding the association between BMI and mortality and contributing to the apparent paradox of a U shaped association.

The attenuation of the observed J shaped relation in analyses confined to never smokers with longer follow-up and the finding of the lowest mortality in the BMI range 20-22 in this group suggest that any increased mortality among never smokers with low BMI is probably a result of residual confounding from unidentified comorbidity. However, the authors were unable to investigate how changes in weight over time might influence their findings.

In a second paper (doi:10.1136/bmj.i2195), Song and colleagues used an interesting strategy to try to find out how weight trajectories from age 5 to 50 years influence all cause and cause specific mortality among adults over 60 years of age.3 Having validated an approach in an earlier study in which people were asked to identify their body shape from outline drawings of different body shapes (somatotypes),4 the investigators studied associations between changes in somatotypes over time and mortality outcomes, using data from two large US prospective cohort studies.

They identified five common patterns or weight trajectories: lean-stable, lean-moderate increase, lean-marked increase, medium-stable/increase, and heavy stable/increase. Unsurprisingly, the authors found that people who reported remaining lean throughout life had the lowest mortality and that those who reported being heavy as children and who remained heavy or gained further weight had the highest mortality. Gaining weight from childhood to age 50 was associated with increased mortality compared with people who reported remaining lean. Weight gain was more strongly associated with cardiovascular than all cause mortality, and the effect was more pronounced among never smokers than ever smokers.

The association between weight gain and cancer mortality was also stronger among never smokers than ever smokers, presumably owing to the higher proportion of obesity related cancers among non-smokers. The stronger association between weight gain and mortality among people with diabetes suggests that diabetes may act as marker of metabolically unhealthy obesity within strata of BMI with the adverse effects of hypertension, dyslipidaemia, and insulin resistance added to the adverse effects of hyperglycaemia. Such findings are a reminder that BMI by itself is an imperfect measure of adiposity.

Recall of body shape is also an imperfect measure. Correlation coefficients between objective and subjective levels of adiposity varied between r=0.36 and r=0.66 in different age groups of men and women. Misclassification bias seems likely, although what effect this might have on the study’s findings is unclear. Interestingly, the authors did not identify repeated loss and regain of weight (weight cycling) as a separate trajectory. This pattern of weight change is thought to increase risk of diabetes, but limited evidence exists to support an effect on mortality.5 6

In conclusion, the study by Aune and colleagues suggests an optimal BMI for lowest mortality likely to apply to European and North American populations. Optimal BMI can be expected to vary by age, ethnicity, and the proportion of people with comorbidity in different populations, and secular declines in mortality may have been even more marked if the prevalence of obesity had not increased. The study by Song and colleagues is an important step forward in furthering our understanding of how weight gain over the life course, particularly in mid-life, is likely to influence health and mortality. Major challenges remain in finding effective ways to prevent weight gain, support weight loss, and prevent weight re-gain, in both individuals and populations.


BMI and all cause mortality: systematic review and non-linear dose-response meta-analysis of 230 cohort studies with 3.74 million deaths among 30.3 million participants.
Aune D, Sen A, Prasad M, Norat T, Janszky I, Tonstad S, Romundstad P, Vatten LJ.
BMJ. 2016 May 4;353:i2156. doi: 10.1136/bmj.i2156.
PMID: 27146380
http://www.bmj.com/content/353/bmj.i2156
http://www.bmj.com/content/bmj/353/bmj.i2156.full.pdf

Abstract

OBJECTIVE:

To conduct a systematic review and meta-analysis of cohort studies of body mass index (BMI) and the risk of all cause mortality, and to clarify the shape and the nadir of the dose-response curve, and the influence on the results of confounding from smoking, weight loss associated with disease, and preclinical disease.

DATA SOURCES:

PubMed and Embase databases searched up to 23 September 2015.

STUDY SELECTION:

Cohort studies that reported adjusted risk estimates for at least three categories of BMI in relation to all cause mortality.

DATA SYNTHESIS:

Summary relative risks were calculated with random effects models. Non-linear associations were explored with fractional polynomial models.

RESULTS:

230 cohort studies (207 publications) were included. The analysis of never smokers included 53 cohort studies (44 risk estimates) with >738 144 deaths and >9 976 077 participants. The analysis of all participants included 228 cohort studies (198 risk estimates) with >3 744 722 deaths among 30 233 329 participants. The summary relative risk for a 5 unit increment in BMI was 1.18 (95% confidence interval 1.15 to 1.21; I(2)=95%, n=44) among never smokers, 1.21 (1.18 to 1.25; I(2)=93%, n=25) among healthy never smokers, 1.27 (1.21 to 1.33; I(2)=89%, n=11) among healthy never smokers with exclusion of early follow-up, and 1.05 (1.04 to 1.07; I(2)=97%, n=198) among all participants. There was a J shaped dose-response relation in never smokers (Pnon-linearity <0.001), and the lowest risk was observed at BMI 23-24 in never smokers, 22-23 in healthy never smokers, and 20-22 in studies of never smokers with =/>20 years' follow-up. In contrast there was a U shaped association between BMI and mortality in analyses with a greater potential for bias including all participants, current, former, or ever smokers, and in studies with a short duration of follow-up (<5 years or <10 years), or with moderate study quality scores.

CONCLUSION:

Overweight and obesity is associated with increased risk of all cause mortality and the nadir of the curve was observed at BMI 23-24 among never smokers, 22-23 among healthy never smokers, and 20-22 with longer durations of follow-up. The increased risk of mortality observed in underweight people could at least partly be caused by residual confounding from prediagnostic disease. Lack of exclusion of ever smokers, people with prevalent and preclinical disease, and early follow-up could bias the results towards a more U shaped association.


Trajectory of body shape in early and middle life and all cause and cause specific mortality: results from two prospective US cohort studies.
Song M, Hu FB, Wu K, Must A, Chan AT, Willett WC, Giovannucci EL.
BMJ. 2016 May 4;353:i2195. doi: 10.1136/bmj.i2195.
PMID: 27146280
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4856853/
http://www.bmj.com/content/bmj/353/bmj.i2195.full.pdf

Abstract

OBJECTIVE:

To assess body shape trajectories in early and middle life in relation to risk of mortality.

DESIGN:

Prospective cohort study.

SETTING:

Nurses' Health Study and Health Professionals Follow-up Study.

POPULATION:

80 266 women and 36 622 men who recalled their body shape at ages 5, 10, 20, 30, and 40 years and provided body mass index at age 50, followed from age 60 over a median of 15-16 years for death.

MAIN OUTCOME MEASURES:

All cause and cause specific mortality.

RESULTS:

Using a group based modeling approach, five distinct trajectories of body shape from age 5 to 50 were identified: lean-stable, lean-moderate increase, lean-marked increase, medium-stable/increase, and heavy-stable/increase. The lean-stable group was used as the reference. Among never smokers, the multivariable adjusted hazard ratio for death from any cause was 1.08 (95% confidence interval 1.02 to 1.14) for women and 0.95 (0.88 to 1.03) for men in the lean-moderate increase group, 1.43 (1.33 to 1.54) for women and 1.11 (1.02 to 1.20) for men in the lean-marked increase group, 1.04 (0.97 to 1.12) for women and 1.01 (0.94 to 1.09) for men in the medium-stable/increase group, and 1.64 (1.49 to 1.81) for women and 1.19 (1.08 to 1.32) for men in the heavy-stable/increase group. For cause specific mortality, participants in the heavy-stable/increase group had the highest risk, with a hazard ratio among never smokers of 2.30 (1.88 to 2.81) in women and 1.45 (1.23 to 1.72) in men for cardiovascular disease, 1.37 (1.14 to 1.65) in women and 1.07 (0.89 to 1.30) in men for cancer, and 1.59 (1.38 to 1.82) in women and 1.10 (0.95 to 1.29) in men for other causes. The trajectory-mortality association was generally weaker among ever smokers than among never smokers (for all cause mortality: P for interaction <0.001 in women and 0.06 in men). When participants were classified jointly according to trajectories and history of type 2 diabetes, the increased risk of death associated with heavier body shape trajectories was more pronounced among participants with type 2 diabetes than those without diabetes, and those in the heavy-stable/increase trajectory and with a history of diabetes had the highest risk of death.

CONCLUSIONS:

Using the trajectory approach, we found that heavy body shape from age 5 up to 50, especially the increase in middle life, was associated with higher mortality. In contrast, people who maintained a stably lean body shape had the lowest mortality. These results indicate the importance of weight management across the lifespan.
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Re: Optimum BMI?

Postby JeffN » Sat Jun 18, 2016 9:31 am

Another study showing the optimal BMI is in the lower end of the healthy weight range

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Full Text Article

Body weight in adolescence and long-term risk of early heart failure in adulthood among men in Sweden
European Heart Journal Jun 2016, ehw221;
DOI: 10.1093/eurheartj/ehw221

http://eurheartj.oxfordjournals.org/con ... rtj.ehw221

Abstract
Aims To study the relation between body mass index (BMI) in young men and risk of early hospitalization with heart failure.

Methods and results
In a prospective cohort study, men from the Swedish Conscript Registry investigated 1968–2005 (n = 1 610 437; mean age, 18.6 years were followed 5–42 years (median, 23.0 years; interquartile range, 15.0–32.0), 5492 first hospitalizations for heart failure occurred (mean age at diagnosis, 46.6 (SD 8.0) years). Compared with men with a body mass index (BMI) of 18.5–20.0 kg/m2, men with a BMI 20.0–22.5 kg/m2 had an hazard ratio (HR) of 1.22 (95% CI, 1.10–1.35), after adjustment for age, year of conscription, comorbidities at baseline, parental education, blood pressure, IQ, muscle strength, and fitness. The risk rose incrementally with increasing BMI such that men with a BMI of 30–35 kg/m2 had an adjusted HR of 6.47 (95% CI, 5.39–7.77) and those with a BMI of ≥35 kg/m2 had an HR of 9.21 (95% CI, 6.57–12.92). The multiple-adjusted risk of heart failure per 1 unit increase in BMI ranged from 1.06 (95% CI, 1.02–1.11) in heart failure associated with valvular disease to 1.20 (95% CI, 1.18–1.22) for cases associated with coronary heart disease, diabetes, or hypertension.

Conclusion
We found a steeply rising risk of early heart failure detectable already at a normal body weight, increasing nearly 10-fold in the highest weight category. Given the current obesity epidemic, heart failure in the young may increase substantially in the future and physicians need to be aware of this.



Mass Media Article

Normal weight teenagers face increased risk of heart failure in middle age, experts 'surprised' to discover

Having a BMI of 20 puts a boy at 22% greater risk of heart failure compared to a teenager with a BMI of 18.5 to 20, researchers were surprised to find

http://www.dailymail.co.uk/health/artic ... cover.html
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Re: Optimum BMI?

Postby JeffN » Fri Jul 15, 2016 7:13 am

From a Meta study of ~10 million people. For those with BMI's around 20-22, perhaps getting to 18.5 is not always a good idea and perhaps 20-22 is best. :)

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Body-mass index and all-cause mortality: individual-participant-data meta-analysis of 239 prospective studies in four continents
The Global BMI Mortality Collaboration†
Published Online: 13 July 2016
(Full Text)
DOI: http://dx.doi.org/10.1016/S0140-6736(16)30175-1

http://www.thelancet.com/journals/lance ... 1/fulltext

Summary

Background
Overweight and obesity are increasing worldwide. To help assess their relevance to mortality in different populations we conducted individual-participant data meta-analyses of prospective studies of body-mass index (BMI), limiting confounding and reverse causality by restricting analyses to never-smokers and excluding pre-existing disease and the first 5 years of follow-up.

Methods
Of 10 625 411 participants in Asia, Australia and New Zealand, Europe, and North America from 239 prospective studies (median follow-up 13·7 years, IQR 11·4–14·7), 3 951 455 people in 189 studies were never-smokers without chronic diseases at recruitment who survived 5 years, of whom 385 879 died. The primary analyses are of these deaths, and study, age, and sex adjusted hazard ratios (HRs), relative to BMI 22·5–<25·0 kg/m2.

Findings
All-cause mortality was minimal at 20·0–25·0 kg/m2 (HR 1·00, 95% CI 0·98–1·02 for BMI 20·0–<22·5 kg/m2; 1·00, 0·99–1·01 for BMI 22·5–<25·0 kg/m2), and increased significantly both just below this range (1·13, 1·09–1·17 for BMI 18·5–<20·0 kg/m2; 1·51, 1·43–1·59 for BMI 15·0–<18·5) and throughout the overweight range (1·07, 1·07–1·08 for BMI 25·0–<27·5 kg/m2; 1·20, 1·18–1·22 for BMI 27·5–<30·0 kg/m2). The HR for obesity grade 1 (BMI 30·0–<35·0 kg/m2) was 1·45, 95% CI 1·41–1·48; the HR for obesity grade 2 (35·0–<40·0 kg/m2) was 1·94, 1·87–2·01; and the HR for obesity grade 3 (40·0–<60·0 kg/m2) was 2·76, 2·60–2·92. For BMI over 25·0 kg/m2, mortality increased approximately log-linearly with BMI; the HR per 5 kg/m2 units higher BMI was 1·39 (1·34–1·43) in Europe, 1·29 (1·26–1·32) in North America, 1·39 (1·34–1·44) in east Asia, and 1·31 (1·27–1·35) in Australia and New Zealand. This HR per 5 kg/m2 units higher BMI (for BMI over 25 kg/m2) was greater in younger than older people (1·52, 95% CI 1·47–1·56, for BMI measured at 35–49 years vs 1·21, 1·17–1·25, for BMI measured at 70–89 years; pheterogeneity<0·0001), greater in men than women (1·51, 1·46–1·56, vs 1·30, 1·26–1·33; pheterogeneity<0·0001), but similar in studies with self-reported and measured BMI.

Interpretation
The associations of both overweight and obesity with higher all-cause mortality were broadly consistent in four continents. This finding supports strategies to combat the entire spectrum of excess adiposity in many populations.


This is fairly consistent with an earleir one that was also on BMI vs. mortality for over 1 million people. It found that the lowest mortality was around BMI of 23.


Body-mass index and mortality in a prospective cohort of U.S. adults.
N Engl J Med. 1999 Oct 7;341(15):1097-105.
PMID: 10511607

https://www.nejm.org/doi/full/10.1056/n ... 0073411501

"In healthy people who had never smoked, the nadir of the curve for body-mass index and mortality was found at a body-mass index of 23.5 to 24.9 in men and 22.0 to 23.4 in women."

Abstract
BACKGROUND:
Body-mass index (the weight in kilograms divided by the square of the height in meters) is known to be associated with overall mortality. We investigated the effects of age, race, sex, smoking status, and history of disease on the relation between body-mass index and mortality.
METHODS:
In a prospective study of more than 1 million adults in the United States (457,785 men and 588,369 women), 201,622 deaths occurred during 14 years of follow-up. We examined the relation between body-mass index and the risk of death from all causes in four subgroups categorized according to smoking status and history of disease. In healthy people who had never smoked, we further examined whether the relation varied according to race, cause of death, or age. The relative risk was used to assess the relation between mortality and body-mass index.
RESULTS:
The association between body-mass index and the risk of death was substantially modified by smoking status and the presence of disease. In healthy people who had never smoked, the nadir of the curve for body-mass index and mortality was found at a body-mass index of 23.5 to 24.9 in men and 22.0 to 23.4 in women. Among subjects with the highest body-mass indexes, white men and women had a relative risk of death of 2.58 and 2.00, respectively, as compared with those with a body-mass index of 23.5 to 24.9. Black men and women with the highest body-mass indexes had much lower risks of death (1.35 and 1.21), which did not differ significantly from 1.00. A high body-mass index was most predictive of death from cardiovascular disease, especially in men (relative risk, 2.90; 95 percent confidence interval, 2.37 to 3.56). Heavier men and women in all age groups had an increased risk of death.
CONCLUSIONS:
The risk of death from all causes, cardiovascular disease, cancer, or other diseases increases throughout the range of moderate and severe overweight for both men and women in all age groups. The risk associated with a high body-mass index is greater for whites than for blacks.


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Jeff
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Re: Optimum BMI?

Postby JeffN » Sat Nov 26, 2016 11:16 am

Combined associations of body weight and lifestyle factors with all cause and cause specific mortality in men and women: prospective cohort study.

BMJ 2016; 355 doi: http://dx.doi.org/10.1136/bmj.i5855 (Published 24 November 2016)
http://www.bmj.com/content/355/bmj.i5855

Abstract
Objective To evaluate the combined associations of diet, physical activity, moderate alcohol consumption, and smoking with body weight on risk of all cause and cause specific mortality.

Design
Longitudinal study with up to 32 years of follow-up.

Setting
Nurses’ Health Study (1980-2012) and Health Professionals Follow-up Study (1986-2012).

Participants
74 582 women from the Nurses’ Health Study and 39 284 men from the Health Professionals Follow-up Study who were free from cardiovascular disease and cancer at baseline.

Main outcome measures
Exposures included body mass index (BMI), score on the alternate healthy eating index, level of physical activity, smoking habits, and alcohol drinking while outcome was mortality (all cause, cardiovascular, cancer). Cox proportional hazard models were used to calculate the adjusted hazard ratios of all cause, cancer, and cardiovascular mortality with their 95% confidence intervals across categories of BMI, with 22.5-24.9 as the reference.

Results
During up to 32 years of follow-up, there were 30 013 deaths (including 10 808 from cancer and 7189 from cardiovascular disease). In each of the four categories of BMI studied (18.5-22.4, 22.5-24.9, 25-29.9, ≥30), people with one or more healthy lifestyle factors had a significantly lower risk of total, cardiovascular, and cancer mortality than individuals with no low risk lifestyle factors. A combination of at least three low risk lifestyle factors and BMI between 18.5-22.4 was associated with the lowest risk of all cause (hazard ratio 0.39, 95% confidence interval 0.35 to 0.43), cancer (0.40, 0.34 to 0.47), and cardiovascular (0.37, 0.29 to 0.46) mortality, compared with those with BMI between 22.5-24.9 and none of the four low risk lifestyle factors.

Conclusion
Although people with a higher BMI can have lower risk of premature mortality if they also have at least one low risk lifestyle factor, the lowest risk of premature mortality is in people in the 18.5-22.4 BMI range with high score on the alternate healthy eating index, high level of physical activity, moderate alcohol drinking, and who do not smoke. It is important to consider diet and lifestyle factors in the evaluation of the association between BMI and mortality.
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Re: Optimum BMI?

Postby JeffN » Mon Apr 03, 2017 7:44 pm

"Those who had a maximum BMI in the overweight range (from 25.0 to 29.9) were 6 percent more likely to die during the follow-up period compared with those who had a maximum BMI in the normal weight range (from 18.5 to 24.9). What's more, those who had a maximum BMI in the obese range (from 30 to 34.9) or severely obese range (35 or above) were 24 percent to 70 percent more likely to die during the follow-up period, compared to those in the normal weight range."


Weight History and All-Cause and Cause-Specific Mortality in Three Prospective Cohort Studies
4 APRIL 2017
Annals of Internal Medicine

http://annals.org/aim/article/2615810/w ... ive-cohort

Abstract

Background:
The relationship between body mass index (BMI) and mortality is controversial.

Objective:
To investigate the relationship between maximum BMI over 16 years and subsequent mortality.

Design:
3 prospective cohort studies.

Setting:
Nurses' Health Study I and II and Health Professionals Follow-Up Study.

Participants:
225 072 men and women with 32 571 deaths observed over a mean of 12.3 years of follow-up.

Measurements:
Maximum BMI over 16 years of weight history and all-cause and cause-specific mortality.

Results:
Maximum BMIs in the overweight (25.0 to 29.9 kg/m2) (multivariate hazard ratio [HR], 1.06 [95% CI, 1.03 to 1.08]), obese I (30.0 to 34.9 kg/m2) (HR, 1.24 [CI, 1.20 to 1.29]), and obese II (≥35.0 kg/m2) (HR, 1.73 [CI, 1.66 to 1.80]) categories were associated with increases in risk for all-cause death. The pattern of excess risk with a maximum BMI above normal weight was maintained across strata defined by smoking status, sex, and age, but the excess was greatest among those younger than 70 years and never-smokers. In contrast, a significant inverse association between overweight and mortality (HR, 0.96 [CI, 0.94 to 0.99]) was observed when BMI was defined using a single baseline measurement. Maximum overweight was also associated with increased cause-specific mortality, including death from cardiovascular disease and coronary heart disease.

Limitation:
Residual confounding and misclassification.

Conclusion:
The paradoxical association between overweight and mortality is reversed in analyses incorporating weight history. Maximum BMI may be a useful metric to minimize reverse causation bias associated with a single baseline BMI assessment.




About-Face on 'Obesity Paradox': Extra Fat Does Raise Risk of Death
By Rachael Rettner, Senior Writer | April 3, 2017 06:49pm E

http://www.livescience.com/58519-obesit ... -risk.html

Being overweight or obese at some point in adulthood may increase the risk of early death, a new study finds.

The findings contradict the so-called "obesity paradox," a phenomenon seen in previous studies in which overweight people seemed to have a reduced risk of early death compared to those who were of normal weight.

But these prior studies relied on weight measurements at a single point in time, which meant the studies couldn't determine if being overweight was really protective against early death, or if a lower weight was a signal that a person was sick and near death. The new study found that when researchers looked at people's weight over many years, the obesity paradox was reversed.

The new finding is "important from a public health perspective, given that about one-third of adults in the U.S. and more than a quarter of the world's population is overweight," study author Edward Yu, a graduate student at the Harvard T.H Chan School of Public Health in Boston, said in a statement. "This is more reason why people should follow a healthy lifestyle and try to keep a normal weight," Yu said. [The Best Way to Lose Weight Safely]

The study analyzed information from more than 225,000 U.S. adults who took part in three large studies. Every two years, participants were surveyed on their body weight, health problems, smoking habits, physical activity and diet.

The researchers used information on participants' height and weight to calculate their body mass index (BMI) over a 16-year period, then determined their highest or "maximum" BMI during this period. The participants were followed for another 12 years, on average. (At the start of this 12-year follow-up period, most participants were in their 50s or 60s.)

During the follow-up period, more than 32,500 participants died. Those who had a maximum BMI in the overweight range (from 25.0 to 29.9) were 6 percent more likely to die during the follow-up period compared with those who had a maximum BMI in the normal weight range (from 18.5 to 24.9).

What's more, those who had a maximum BMI in the obese range (from 30 to 34.9) or severely obese range (35 or above) were 24 percent to 70 percent more likely to die during the follow-up period, compared to those in the normal weight range.

"The obesity paradox has always been something that we've questioned," said Dr. Vincent Pera, director of weight management at the Miriam Hospital in Providence, Rhode Island, who was not involved in the new study.

This new research has a number of strengths over prior studies, including that it gathered data on participants' weight throughout the study and didn't ask participants to think back to what they weighed at some point in the past, Pera said. As a result, the authors were able to make their conclusion in a valid way, Pera said.

Still, additional studies could further examine the link between obesity and risk of early death, he said. For example, researchers could look at whether the duration of a person's obesity affects the individual's risk of death, Pera said.

Overall, studies like the current one can help doctors convey to their patients the importance of controlling their weight, Pera said. "When studies like this seem to align with what, at least, the clinical picture [of obesity] seems to show, I think we feel more confident in speaking to patients about weight control and the benefits of weight control," he said.

The study was published today (April 3) in the journal Annals of Internal Medicine.

Original article on Live Science.
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Re: Optimum BMI?

Postby JeffN » Thu Jun 15, 2017 7:11 am

Weight-related diseases and deaths can affect those who are overweight - not just the obese

In Health
Jeff

Study

ORIGINAL ARTICLE
Health Effects of Overweight and Obesity in 195 Countries over 25 Years
The GBD 2015 Obesity Collaborators
June 12, 2017
DOI: 10.1056/NEJMoa1614362

BACKGROUND
Although the rising pandemic of obesity has received major attention in many countries, the effects of this attention on trends and the disease burden of obesity remain uncertain.

METHODS
We analyzed data from 68.5 million persons to assess the trends in the prevalence of overweight and obesity among children and adults between 1980 and 2015. Using the Global Burden of Disease study data and methods, we also quantified the burden of disease related to high body-mass index (BMI), according to age, sex, cause, and BMI in 195 countries between 1990 and 2015.

RESULTS
In 2015, a total of 107.7 million children and 603.7 million adults were obese. Since 1980, the prevalence of obesity has doubled in more than 70 countries and has continuously increased in most other countries. Although the prevalence of obesity among children has been lower than that among adults, the rate of increase in childhood obesity in many countries has been greater than the rate of increase in adult obesity. High BMI accounted for 4.0 million deaths globally, nearly 40% of which occurred in persons who were not obese. More than two thirds of deaths related to high BMI were due to cardiovascular disease. The disease burden related to high BMI has increased since 1990; however, the rate of this increase has been attenuated owing to decreases in underlying rates of death from cardiovascular disease.
.
CONCLUSIONS
The rapid increase in the prevalence and disease burden of elevated BMI highlights the need for continued focus on surveillance of BMI and identification, implementation, and evaluation of evidence-based interventions to address this problem.


MMA

Weight-related deaths can affect those who are overweight -not just the obese

"The paper, published in the the New England Journal of Medicine, said the findings highlighted "a growing and disturbing global public health crisis".

"People who shrug off weight gain do so at their own risk - risk of cardiovascular disease, diabetes, cancer and other life-threatening conditions," said Dr Christopher Murray, author of the study and director of the Institute of Health Metrics and Evaluation at the University of Washington.

"Those half-serious New Year's resolutions to lose weight should become year-round commitments to lose weight and prevent future weight gain.""

http://www.bbc.co.uk/news/health-40220182
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