Low-fat dietary pattern and weight change over 7 years: The Women's Health Initiative Dietary Modification Trial

Abstract

Context: Obesity in the United States has increased dramatically during the past several decades. There is debate about optimum calorie balance for prevention of weight gain, and proponents of some low-carbohydrate diet regimens have suggested that the increasing obesity may be attributed, in part, to low-fat, high-carbohydrate diets. Objectives: To report data on body weight in a long-term, low-fat diet trial for which the primary end points were breast and colorectal cancer and to examine the relationships between weight changes and changes in dietary components. Design, Setting, and Participants: Randomized intervention trial of 48 835 postmenopausal women in the United States who were of diverse backgrounds and ethnicities and participated in the Women's Health Initiative Dietary Modification Trial; 40% (19 541) were randomized to the intervention and 60% (29 294) to a control group. Study enrollment was between 1993 and 1998, and this analysis includes a mean follow-up of 7.5 years (through August 31, 2004). Interventions: The intervention included group and individual sessions to promote a decrease in fat intake and increases in vegetable, fruit, and grain consumption and did not include weight loss or caloric restriction goals. The control group received diet-related education materials. Main Outcome Measure: Change in body weight from baseline to follow-up. Results: Women in the intervention group lost weight in the first year (mean of 2.2 kg, P