Weight loss interventions for breast cancer survivors: impact of dietary pattern

Abstract

Body weight management is not emphasized in clinical practice guidelines for breast cancer survivors, reflecting the lack of evidence that weight loss improves prognosis. Even if this situation changes, the optimal design for weight loss interventions is unclear. We conducted a 6-month non-randomized, controlled weight loss intervention in 249 post-menopausal breast cancer survivors. This paper reports effects on two secondary endpoints, change in body weight and composition. Participants were predominantly non-Hispanic whites (89%) with a mean age of 54.9 ± 9.2 years, a mean BMI of 29.0 ± 2.6 kg/m: (2) and an average of 43 ± 5% body fat. Two dietary interventions, low fat or low carbohydrate, were investigated and consisted of a 42 day cycle of menus and recipes. Weight loss counseling and anthropometric assessment were provided at monthly clinic visits. One hundred ninety-two women completed the trial (77% retention). In comparison to the nonintervention control, both intervention arms achieved significant decreases in body weight (12.5%), body fat (27.5%), waist circumference (9.5%), and hip circumference (7.8%) (all p < 0.001) with minimal effects on lean mass (1.3% decrease). Median time to 5 and 10% weight loss was 2 (95% confidence interval = 1 to 3) and 4 (95% confidence interval = 3 to 5) months, respectively, and 23% of participants experienced ≥ 15% weight loss. Loss of body weight and fat mass was rapid and substantial irrespective of dietary approach when a structured program was provided with monthly anthropometric assessment and weight loss counseling.

Trial registration: ClinicalTrials.gov NCT01315483.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1. Flow diagram for screening, assignment, and follow-up of the study participants.

Fig 2. Cumulative Loss of Body Weight, Body Fat, and Lean Body Mass According to Study Group.

(A) average cumulative weight loss (kg); (B) average cumulative fat loss (kg); (C) average cumulative loss of lean mass (kg) as a function of time. Values are means ± SEM. LC, low carbohydrate. LF, low fat.

Fig 3. Percent change in Initial Body Weight According to Intervention Arm by Month of Weight Loss.

Detailed information on individual success in each intervention arm, box plots of the percent change from initial weight by intervention arm at each of the 6 times points were constructed in a format into which a symmetrical dot density plot was integrated. The box plots show each participant’s data as well as indicating the 25th, 50th and 75th percentiles for weight change achieved. These plots show the progressive increments in change in body weight over time by intervention arm and permit a comprehensive view of the magnitude of variation in response.

Fig 4. Time-to-Event Analysis for Weight Loss Success According to Intervention Arm.

Kaplan-Meier plots were constructed in order to quantify the time frame over which participants in each intervention arm achieved at least a 5%, or 10% reduction in body weight relative to initial body weight. Each plot shows the percent of women in each arm that achieved at least the stated percent weight loss by month. (A) greater than 90% of all women in both intervention arms achieved at least 5% weight loss with a median time to achieving this goal of 2 months (95% CI = 1 to 3 months). Change occurred more rapidly in the low carbohydrate intervention arm but the differences were not statistically significant, tested using a Cox proportional hazard model controlling for BMI, RMR, steps, and elapsed time from end of treatment. (B) median time to loss of ≥ 10% of initial body weight was 4 months (95% CI = 3 to 5 months). LC, low carbohydrate. LF, low fat.