More data from the Women’s Health Initiative study that shows restricting fat is a fat lot of good

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At the end of last year I reported on the findings of the mammoth Women’s Health Initiative trial. The trial was initiated in 1993, and recruited a total of almost 50,000 post-menopausal women and followed them for an average of about 8 years. About 60 per cent of these women were allowed to continue on their normal diet (the control group). The remaining 40 per cent of women were instructed to make their diet ‘healthier’ but reducing total fat to 20 per cent of calories, to eat at least 5 portions of fruits and vegetables a day, and to eat 6 or more portions of wholegrains a day. This group ” the intervention group ” received frequent group sessions designed to educate these women about healthy eating and support them in their quest.

Overall, the intervention group ended up eating ‘better’, including (compared to the control group) 22 per cent less fat, 23 per cent less saturated fat and 20 per cent less cholesterol. Despite this, as I reported in a blog post in November, this had not impact on risk of many different forms of cancer or body weight. It was also found that the women eating the lower-fat diet did not experience any protection from risk of heart disease or stroke either [1]. Basically, the Women’s Health Initiative results, to date, have shown that lower fat eating has provided no discernible benefits, even in the long term.

Those who have held out hope that the WHI trial may finally turn up some good news and therefore go some way to vindicating the low-fat paradigm were disappointed again, this week, on the publication of yet another study that assessed data from this trial [2]. This time, the focus was diabetes. And, yet again, the group eating the lower-fat diet were not found to be at a statistically significant reduced risk of this major condition compared to those eating, essentially, what they liked.

The authors point out that there was an association between eating less fat and reduced risk of diabetes. The lower-fat consuming group also lost about 2 kg more weight over the course of the study. Weight loss may reduce the risk of diabetes. Once this was accounted for, the relationship between reduced fat intake and lower risk of diabetes disappeared. This led the authors to conclude: ‘Weight loss, rather than macronutrient composition, may be the dominant predictor of reduced risk of diabetes. So, just to summarise, the lower-fat regime utilised in the Women’s Health Initiative study did not protect women against cardiovascular disease, cancer or diabetes. Fat lot of good, then.

If weight loss is the goal, then my advice is generally to opt for a lower-carb approach. See here and here for more details on this, including the results of two long-term studies that have found carbohydrate control to bring superior results in terms of weight loss than low-fat eating in the long term.


1. Howard BV, et al. Low-fat dietary pattern and risk of cardiovascular disease: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial. JAMA 2006;295(6):655-66

2. Tinker LF, et al. Low-Fat Dietary Pattern and Risk of Treated Diabetes Mellitus in Postmenopausal Women. Arch Intern Med. 2008;168(14):1500-1511

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