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[MR]

As part of the Women's Health Initiative (the same very large, long-term clinical trial that confirmed that finally showed convincingly that HRT was a Bad Thing), 48 835 postmenopausal women were randomized to receive either "group and individual sessions to promote a decrease in fat intake and increases in vegetable, fruit, and grain consumption [but without] weight loss or caloric restriction goals" as a "healthy" low-fat diet, or were left on their own with "diet-related education materials." (1)

"Women in the intervention group lost weight in the first year (mean of 2.2 kg, P<.001) and maintained lower weight than control women during an average 7.5 years of follow-up (difference, 1.9 kg, P<.001 at 1 year and 0.4 kg, P = .01 at 7.5 years). ... Weight loss was greatest among women in either group who decreased their percentage of energy from fat. A similar but lesser trend was observed with increases in vegetable and fruit servings, and a nonsignificant trend toward weight loss occurred with increasing intake of fiber."

This of course doesn't tell us much about the relative merits of such an approach vs a higher-fat and -protein, low-glycemic diet -- particularly when both groups receive similar intensity of coaching, and with weight loss (and thus at some level Caloric control) as a specific goal. We've had results from an awful lot of these in the last couple of years, and the latter type seem to be more successful, even tho' the initially more impressive differences are attenuated after the first 6 mo.

On the other hand, it's really somewhat impressive that these folks seemingly 'spontaneously' dropped and kept off (relatively) nearly 5 lbs for nearly 8 years. Yet I put 'spontaneously' in sneer quotes because, despite the lack of a Caloric or weight loss goal, receiving guidance that helps one to do all of the above SHOULD help one to lose weight by lowering energy density; and presumably, especially when women were first recruited (between 1993 and 1998), a low-fat diet would have been recognized by most participants as being in synch with widely-promoted guidance for weight loss.

Indeed, while it may well be coincidental, it's a bit striking that the 'spontaneous' weight loss achieved in a year (& maintained later, at least relative to their essentially AL controls) in the low-fat gorup in this study (1) is similar to the amount lost in the low-fat weight-loss intervention group in the 2 low-carb vs. low-fat studies extended for this long -- but, again, in those studies, the low-carb dieters still kept off more weight despite the regression (which APPEARED to be occurring in both groups): –4.3 vs. –2.7 kg in (2), and -5.1 vs -3.1 kg in (3)). The most obvious counter to focussing too much on the numerical coincidence is that the WHI women were 'merely' quite overweight (average BMI 29.1 in both arms), vs actually obese (>35 in both).

An even better design would be a diet that specifically counselled more veggies and fruit (as in this study) but ALSO more protein and GOOD fat, at the expense of dense carbohydrates and junk generally -- ie, a full-blown Zonish one. Such studies as have been done have shown the health and/or weight loss benefits such an approach over an ADA low-fat one, but have not been extended for this long.

-MR




1. Barbara V. Howard, PhD; JoAnn E. Manson, MD, DrPH; Marcia L. Stefanick, PhD; Shirley A. Beresford, PhD; Gail Frank, DrPH; Bobette Jones, DrPH; Rebecca J. Rodabough, MS; Linda Snetselaar, PhD; Cynthia Thomson, PhD; Lesley Tinker, PhD; Mara Vitolins, DrPH; Ross Prentice, PhD
Low-Fat Dietary Pattern and Weight Change Over 7 Years: The Women's Health Initiative Dietary Modification Trial
JAMA. 2006 January 4;295(1):39-49.
http://jama.ama-assn.org/cgi/content/full/295/1/39

2: Foster GD, Wyatt HR, Hill JO, McGuckin BG, Brill C, Mohammed BS, Szapary PO, Rader DJ, Edman JS, Klein S.
A randomized trial of a low-carbohydrate diet for obesity.
N Engl J Med. 2003 May 22;348(21):2082-90.
PMID: 12761365 [PubMed - indexed for MEDLINE]

3. Stern L, Iqbal N, Seshadri P, Chicano KL, Daily DA, McGrory J, Williams M, Gracely EJ, Samaha FF.
The effects of low-carbohydrate versus conventional weight loss diets in severely obese adults: one-year follow-up of a randomized trial.
Ann Intern Med. 2004 May 18;140(10):778-85.
PMID: 15148064 [PubMed - indexed for MEDLINE]