Saturday, January 31, 2015

The Nutrition Debate #284: The A TO Z Weight Loss Study: a Randomized Trial

A dear reader – and I mean that sincerely because I wouldn’t write this blog except for my readers – was disappointed (upset, actually) that I said, “…if you are insulin resistant, as almost all fat people are…” Okay, “fat people” is an inflammatory phrase, and I have never used it before, but that is not what upset Valerie. It was an assumption, and a slight exaggeration that I made, that did the trick. She concluded: “I wish your ‘nutrition debate’ weren’t so one-sided.”
Valerie’s frustration (and upset) is a result of my writing about two overlapping and related but different phenomena: the co-incident epidemics of diabetes and obesity that have come together in the last 35 years. It all began with the publication of the Dietary Guidelines for Americans in 1980, the U.S. government’s attempt to tell us as a population what to eat. That followed the 1977 Dietary Goals for Americans produced by a Select Committee of Congress: the McGovern Commission.
This combination of type 2 diabetes and obesity is so prevalent today that the word “diabesity” has been coined. However, as Valerie points out, not all “fat people” have Insulin Resistance (IR), a requisite condition for progression from a normal glucose metabolism to Impaired Glucose Tolerance (IGT), Impaired Fasting Glucose (IGT), and then to a frank diagnosis of Type 2 Diabetes Mellitus (T2DM). That is the Natural History of Type 2 Diabetes. Apparently Valerie is not Insulin Resistant or therefore by definition a type 2 diabetic (FBG at diagnosis ≥126mg/dL) or pre-diabetic (FBG from 100 to 125mg/dL).
So, I give Valerie her point that, “…there are plenty of slim people with insulin resistance and plenty of fat people without insulin resistance…” I will resist getting into a “pissing contest” over percentages. I will concede that apparently Valerie is one of them. But I will contest the assertion Valerie makes that “fat people without insulin resistance” did not benefit from the “A to Z diet trial.” She states erroneously that “low-carb diets don’t help [them], if you remember the A to Z diet trial.”
The A to Z diet trial, not to be confused with a statin trial by a very similar name, was a “Twelve-month randomized trial conducted in the United States from February 2003 to October 2005 among 311 free-living, overweight/obese (body mass index, 27-40) nondiabetic [emphasis mine], premenopausal women.” Note: this trial EXCLUDED (type 2) diabetics, which by definition means that the participants did not have IR. It was a “Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors…,”published in JAMA in July 2007. The following are excerpts from the ABSTRACT:
MAIN OUTCOME MEASURES: Weight loss at 12 months was the primary outcome. Secondary outcomes included lipid profile (low-density lipoprotein, high-density lipoprotein, and non-high-density lipoprotein cholesterol, and triglyceride levels), percentage of body fat, waist-hip ratio, fasting insulin and glucose levels, and blood pressure.”
“RESULTS: Weight loss was greater for women in the Atkins diet group compared with the other diet groups at 12 months, and mean 12-month weight loss was significantly different between the Atkins and Zone diets. Weight loss was not statistically different among the Zone, LEARN, and Ornish groups. At 12 months, secondary outcomes for the Atkins group were comparable with or more favorable than the other diet groups.”
“CONCLUSIONS: In this study, premenopausal overweight and obese women assigned to follow the Atkins diet, which had the lowest carbohydrate intake, lost more weight at 12 months than women assigned to follow the Zone diet, and had experienced comparable or more favorable metabolic effects than those assigned to the Zone, Ornish, or LEARN diets…”
So, just to be perfectly clear, non-diabetic, premenopausal overweight and obese women who ate the diet with the lowest carbohydrate intake lost the most weight and had the best improvement in related risk factors (including “lipid profile (low-density lipoprotein, high-density lipoprotein, and non-high-density lipoprotein cholesterol, and triglyceride levels), percentage of body fat, waist-hip ratio, fasting insulin and glucose levels, and blood pressure.”)
In other words, the low-carb diet DID help “fat people without insulin resistance,” and by a large margin. After 12 months, the Atkins cohort actually lost 3 times as much weight at the Zone cohort and twice as much as the average Ornish and LEARN dieter and had “comparable or more favorable metabolic effects” than those on the Zone, Ornish, or LEARN diets.

I’m sorry to have to come down so hard on this point, but it must be made clear to all my dear readers that low-carb diets do work (for the vast majority of people, if I have to hedge). If you haven’t given it an honest try, you really should.


  1. This is not a "pissing contest" about percentages. I was questioning your assertion that almost all fat people are insulin resistant. I don't see what data makes you so sure about it.

    As for the A to Z trial, some participants did have insulin resistance (but not diabetes). My previous comment was about the subgroup analysis they did, not the overall averages [sorry, I should have made that clearer]. Among the participants with IR, Atkins was the best. Among the participants without IR, Ornish was the best if I remember correctly.

    I think this is where the author talks about it:

  2. Valerie, thanks for commenting again. I just watched the 1:16 YouTube presentation by Christopher Gardner. I was pretty impressed that a 25 year vegetarian could be and was as objective as he was. He admitted it was a "bitter pill" to have to report the superiority Atkins to the other diets,

    With respect to the "bone" you have picked re Insulin Resistance, I paid particular attention. At about minute 42 he shows a slide from another study that compares IS and IR but this was not from the A to Z study. Then, at about minute 44, he shows a slide from the A to Z study that says (and I'm paraphrasing): For insulin resistance, the low fat diet is 'ineffective' compared to the low carb. Then at minute 45, in answer to a question that was unintelligible, he says, the more overweitht you are, the fore insulin resistant you are. Later on, in answer to another question, he says, if you have metabolic syndrome, you probably have insulin resistance. Of course, he is addressing a 'naive' audience, and I think you and I could have a more nuanced conversation (debate?) on the subject, but I could not find where he said anything which is dissonant with my admittedly somewhat exaggerated and insensitive statement that "almost all fat people are insulin resistant."
    PS: Have you ever had a HOMA2 test. An endo I saw two years ago (1 time, he fired me) did one at my request. His nurse said he had never done one in 12 years and he had to look it up. He said it was mostly done for research but he agreed to do it. My beta cell function was 68.2% and my insulin sensitivity was 94.6%. I was quite surprised by both. I think you would find the column #86 and #87 interesting. I link them below.