Tuesday, January 31, 2006

JAMA: Atkins, Ornish, Weight Watchers & Zone - One-Year Comparison

Yesterday I pointed out the weight loss discrepancies, based on calorie intake of participants following various diets in a study published earlier this month in JAMA - Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease Risk Reduction.

When viewed solely from a "calorie in - calorie out" perspective the results suggest that calorie intake alone is not the single determinant of weight loss. This is something I've been saying for years and still remain surprised when, at the end of a study where weight loss does not jibe with calorie intake, researchers fail to question why! They are quick to state weight loss that is aligned with calorie intake, which is almost always from a short-term period - so why ignore the question of why, over time, "calories in-calorie out" fails to produce predictable weight loss?

That's just one question I have.

Another is why didn't the researchers in this study make it clear that none of the groups followed over the year were able to follow the rules of their diet? And, why didn't they acknowledge that even during the initial intensive start period, where education and support were provided, the groups couldn't follow the "rules" of each diet?

For example, those assigned to the Ornish diet were supposed to limit fat intake to just 10% of their calories, yet consumed 17% of their calories from fat during the first two months of the study. By the end of one-year the group was averaging 31.6% of their calories from fat. This group was clearly not following the Ornish diet!

Nor did the group assigned the Atkins diet actually follow the Atkins diet rules. If they had followed the rules, at the end of month one they would have consumed just 30g of carbohydrate as part of their diet, and just 50g of carbohydrate by the end of month two. Instead, during this two month period of education & support, this group consumed an average of 68g of carbohydrate in month one and 137g of carbohydrate in month two.

Hello! This group was not following the low-carb Atkins diet!

In fact, none of the groups got the macronutrient ratios of their diets right. Those on Ornish and Zone ate way too much fat for their diet; those on Weight Watchers ate too much fat with too little carbohydrate; and those on Atkins ate too much carbohydrate with too little protein.

If nothing else this study tells us one thing - how to waste time and research money.

Those conducting this study failed to properly educate their participants and encourage adherence to the dietary rules of each plan. They did have ample opportunity to do so in the first eight weeks of the study and from their own data it is obvious they didn't accomplish such an important part of the process required to start and follow a dietary approach - basic education of their participants. So, at the end of one-year this study tells us nothing and was nothing more than a waste of research dollars.

1 comment:

  1. 137g of carbs?! Damn! I maybe eat that much on a day I fall off my diet, but I've been on Atkins almost 2 years now and know that horrible things happen in my body when I exceed 90g of carbs. And the last couple of months my carbs have been around 40g while I try to get the last few stubborn pounds off (with limited success). 137g would be in my dreams maybe! My maintainance level is somewhere between 60 and 90g a day, but no more than 90.