karin_kiwi wrote:Jeff, my experience with going down to 600 calories/day (purely because busy, not because intending to do so) and not losing weight until I start eating more is actually my experience, not anything I've ever come across through "diet wisdom."
Hi Karin
I appreciate your kind words, and I am not doubting your experience and I am sure you are very careful about your efforts to document your experience.
karin_kiwi wrote:And I know that there have been times I have not lost weight for 3-4 weeks in a row, even when on around 1000-1400 cal/day. From what you say, that would be impossible.
I said it was impossible for someone to be at a weight plateau and for them to have to consume more calories to continue losing weight.
BTW, there is a tremendous variance between 1000-1400 calories (over 40%) and so that variance alone can account for much of what is experienced
There are also several other things to consider.
1) even if you weigh and measure every single gram of food, there is still an over 20% lee way that is allowed in the caloric values you may be using. This is the normal allowance. It can be greater. And there is no standard from one sample to another and the lee way can be "up" or "down."
2) There are "within a day," "day to day", and even weekly changes in fluid volume, glycogen stores and in the contents of the digestive tract that together can account for 6-10 lbs or more change in weight in the average person. Without knowing or tracking this, people often associate this potential effect on their weight, with their calorie input and/or output yet it has nothing to do with calorie balance. I worked with one very large athlete whose weight changed 20 lbs within a day due to fluid changes. Again, this is measured in a metabolic chamber, but not at home.
2) The body can also mildly adapt/adjust its metabolism in response to a sudden increase or decrease in food intake but it only last a brief period (a day or two) and its not the actual "starvation" response. This adjustment maybe in heat, or mildly altered metabolism, and can be recorded in a metabolic chamber but can not be recorded at home.
3) People can stop losing weight during their efforts especially after a period of significant weight loss, and/or gain weight while eating the same amount of food, as someones BMR is lower due to less mass of the body. Some people call this a plateau. The solution is to increase the calorie deficit by eating less, or burning more.
So, if someone weights 200 and burns 2000 calories and exercise 500, their total caloric out is 2500. If they eat 2250, they will lose weight. If they lose 50 lbs, and now weight 150, they burn 1500 calories and if they still exercise 500, their total calorie out is 2000. If they keep eating 2250, they will no longer lose weight and may gain weight. The solution is decreasing caloric intake and/or increasing activity.
4) every single experiment done on every single animal ever tested in laboratory settings and metabolic wards/chambers in the last 70 years, have shown that as long as calories in are less than calories out, the animal tested will lose weight. Even when those tested were ones who said they needed to eat more to lose weight, till they were tested under ideal circumstances and no exception was found. I would challenge you and/or anyone else to find the experiment where an animal (with a body fat above the level of essential fat), consumed a low amount of calories and was at a weight plateau and had to consume more calories in order to lose weight.
If this other experience is so common, we should be able to document it in the lab, but it has never be done inspite of many attempts to document it
However, we have many examples where when the subjects reach that point of plateau, that if we give them less food/calories, they start losing weight.
In fact, here are several examples of the published research where the subjects consumed either no calories or a very low amount for many weeks/months and never stopped losing weight. At no time did they have to feed them "more" calories to get them to continue losing weight.
Drenick EJ, Swenseid ME, Blahd WH, Tuttle S. Prolonged starvation as a treatment for severe obesity. JAMA 1964;187:100-105.
Thompson TJ, Runcie J, Miller V. Treatment of obesity by total fast for up to 249 days. Lancet 1966;2:992-996.
Stewart WK, Fleming LW. Features of a successful therapeutic fast of 382 days' duration. Postgrad Med J 1973;49:203-209.
Same with the subjects in the Bio-Sphere who were closely monitored under a controlled situation by a medical doctor. They lived for 2 years under a form of food restriction and it took almost 18 months to see their weight begin to stabilize.
Energy metabolism after 2 y of energy restriction: the biosphere 2 experiment. Am J Clin Nutr. 2000 Oct;72(4):946-53.
The only exception known is free living human beings under free living conditions where their tools for measuring energy balance are way less than ideal.
In Health
jeff