The Atkins, Ornish, Weight Watchers, and Zone diets were studied to determine possible benefits for weight loss and heart disease risk reduction in a randomized trial lasting for one year.  The conclusions published in January of 2005 in the Journal of the American Medical Association were: “Each popular diet modestly reduced body weight and several cardiac risk factors at 1 year. Overall dietary adherence rates were low, although increased adherence was associated with greater weight loss and cardiac risk factor reductions for each diet group.”¹   These results suggest that it makes no difference which diet you follow – low-fat or high-fat, high-carbohydrate or low-carbohydrate, vegetable-food-based or animal-food-based – the benefits are the same, as long as you follow the diet. How can this be?

How Did the Ornish Diet Perform?

I asked Dean Ornish, MD, about this study and he provided me with information that will soon be published in the “Letters to the Editor” of the Journal of the American Medical Association.  In his letter he points out that his low-fat, near-vegetarian diet has been scientifically shown to reverse atherosclerosis, decrease angina (chest pains), bring about permanent weight loss (5 years or longer) and reduce cardiac events (such as heart attacks) by 2.5 times.  The other diets have no published research that shows benefits for heart disease – of more concern is a published report on the Atkins Diet demonstrating worsening of blood flow to the heart.²

According to Dr. Ornish, data from this study really showed greater weight loss, cholesterol, and blood sugar reductions on the Ornish diet than with the other diets.   However, in truth, the differences in results are barely visible.  How can this be?

Lack of Adherence Spoils Benefits

The improvements shown by any of the programs tested are nothing to brag about.  Consider that after one year the average weight losses were 5 to 7 pounds and reductions of cholesterol were 4 to 11 mg/dl on ANY of the programs.  The reason all these diets “fail” to make sustained improvements for one year is lack of adherence to the program – no surprise here. 

Diets are hard to follow, even when highly structured for the participants.  A January 2005 review of major commercial (like Weight Watchers, Jenny Craig, Optifast) and “organized self-help weight loss” (eDiet, TOPS, Overeaters Anonymous) programs found, except for Weight Watchers, that there was little evidence to support their value.³  Here again, lack of adherence was the primary downfall. 

The Ornish diet – a starch-based, near-vegetarian diet – when followed, has the potential to help people the most because it is inherently the healthiest.  When only those who completed the study were included in the analysis, those on the Ornish diet lost on average 14.5 pounds (6.6 Kg) and reduced their cholesterol by 21.5 mg/dl – by far the best results of all the diets tested.

My conclusion from this study is: if you are not going to stick to a diet, it really makes little difference which one you choose to follow temporarily.  But, what if you are serious about keeping that extra weight off?  Then does your choice make a difference?

The Heart Association Says: Popular Diets Sacrifice Your Health

All the popular diets cause weight loss or no one would ever follow them.   However, most – which these days means high protein diets – produce weight loss at the expense of the participants’ health. The Nutrition Committee of the American Heart Association (AHA) in a report in the October 9, 2001 issue of their journal Circulation said this best:⁴

“High-protein diets typically offer wide latitude in protein food choices, are restrictive in other food choices (mainly carbohydrates), and provide structured eating plans. They also often promote misconceptions about carbohydrates, insulin resistance, ketosis, and fat burning as mechanisms of action for weight loss … These diets are generally associated with higher intakes of total fat, saturated fat, and cholesterol because the protein is provided mainly by animal sources. In high-protein diets, weight loss is initially high due to fluid loss related to reduced carbohydrate intake, overall caloric restriction, and ketosis-induced appetite suppression. Beneficial effects on blood lipids and insulin resistance are due to the weight loss, not to the change in caloric composition … High-protein diets are not recommended because they restrict healthful foods that provide essential nutrients and do not provide the variety of foods needed to adequately meet nutritional needs. Individuals who follow these diets are therefore at risk for compromised vitamin and mineral intake, as well as potential cardiac, renal, bone, and liver abnormalities overall.”

Advocates of high-protein diets say their approach reduces the risk of heart disease.  The Nutrition Council of the AHA says:  “A diet rich in animal protein, saturated fat, and cholesterol raises low-density lipoprotein (LDL) cholesterol levels, an effect that is compounded when high-carbohydrate, high-fiber plant foods that help lower cholesterol are limited or eliminated.”  “High-protein diets may also be associated with increased risk for coronary heart disease due to intakes of saturated fat, cholesterol, and other associated dietary factors.”

Advocates of high-protein diets say their approach is especially good for people with diabetes.  The Nutrition Council of the AHA says:  “A very-high-protein diet is especially risky for patients with diabetes, because it can speed the progression, even for short lengths of time, of diabetic renal disease.”

The McDougall Diet: A Best-kept Secret

You noticed, I’m sure, that our approach was not included in this evaluation.  Why not? For some unexplained reason we have been out of most people’s sight, including the media’s.  In one way, that is OK, because we largely escape harsh publicity that can be hurtful.  However, those of you who have discovered us over the past 28 years know our true value. 

The first book Mary and I wrote in 1979 was called Making the Change, because we have always understood that “permanent change” is the bottom line.  It is not a question of whether or not a low-fat, pure-vegetarian diet will cause you to regain lost health and appearances, but will you do it? – will you make the change, permanently?  Over the past three decades all of our efforts have been directed towards ways to help people make enduring changes.  This effort has taken the form of booklets, books, newsletters, videos, DVDs, lectures, and radio and TV shows.  However, our most effective means to help people has been our 10-day live in program.  We believe that we are different from other programs* for these reasons:

*Ornish, Pritikin, Kempner, Swank, and similar low-fat, vegetable-based diets share some of these same benefits.  I find clear rules with distinct boundaries are easier to follow than “moderation,” which distinguishes us from the other low-fat diets. A little chicken and dairy too soon becomes a lot.

References:

1)  Dansinger ML, Gleason JA, Griffith JL, Selker HP, Schaefer EJ.  Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial.  JAMA. 2005 Jan 5;293(1):43-53.

2)  Fleming RM.   The effect of high-protein diets on coronary blood flow.  Angiology. 2000 Oct;51(10):817-26.

3)Tsai AG, Wadden TA.  Systematic review: an evaluation of major commercial weight loss programs in the United States.  Ann Intern Med. 2005 Jan 4;142(1):56-66.

4)  St. Jeor, S.  Dietary protein and weight reduction: a statement for healthcare professionals from the Nutrition Committee of the Council on Nutrition, Physical Activity, and Metabolism of the American Heart Association. Circulation 2001 Oct 9;104(15):1869-74.