Coincident with the December publication of data from the Women’s Health Initiative (WHI) Dietary Modification Trial , which failed to show decreased risk of breast cancer, colon cancer or coronary heart disease in a controlled trial of 48,835 postmenopausal women (50–79 years old) who lowered their fat intake by 7.8% and increased their carbohydrate intake by 7.6%, there appeared an additional study of a subset of the same group of women and data, this time examining whether the same dietary change had brought about any significant changes in fat mass, lean mass and/or percentage body fat, measured by DXA scans at 1 year, 3 years and 6 years of follow-up . The intervention women experienced significantly greater reductions in percentage body fat, fat mass, and lean mass at years 1 and 3 than did women in the comparison group (all [i]p[/i] < 0.05). At year 6, only the fat mass change was significantly different between groups. Overall, the intervention was associated with reductions in percentage body fat (-0.8%; 95% confidence interval (CI) -1.0%, -0.6%); fat mass (-1.1 kg; 95% CI -1.3, -0.8 kg), and lean mass (-0.17 kg; 95% CI -0.28, -0.06 kg) during follow-up (all [i]p[/i] < 0.003). Intervention associations varied by race-ethnicity, body mass index, diabetes, and hormone therapy and remained significant after adjustment for physical activity. Only non-diabetic, white intervention subjects lost percentage of body fat, more fat mass and (in the case of non-hormone replacers) more lean mass at years 1 and 3, but by year 6 only the fat mass loss was greater in the intervention group. Women on hormone replacement did not lose lean mass; others did. The authors acknowledge that the observed loss of lean mass is not a desirable change. They emphasize that body mass index may fail to accurately show percentage body fat which can increase with age in persons not gaining weight. Compliance was assessed only on patient reporting.
Providence, Utah, USA
Howard BV, Curb JD, Eaton CB, et al. Low-fat dietary pattern and lipoprotein risk factors: the Womens Health Initiative Dietary Modification Trial. Am J Clin Nutr 2010;91:860-74.
Carty CL, Kooperberg C, Neuhouser ML, et al. Low-fat dietary pattern and change in body-composition traits in the Womens Health Initiative Dietary Modification Trial. Am J Clin Nutr 2010 Dec 22. Epub ahead of print.