OBJECTIVE: To determine the effectiveness of an intensive dietary intervention on diet and body mass in women with breast cancer.

DESIGN: Randomized clinical trial.

SUBJECTS: 172 women aged 20 to 65 years with stage I or II breast cancer.

INTERVENTION: A 15-session, mainly group-based and dietitian-led nutrition education program (NEP) was compared to a mindfulness-based stress reduction clinic program (SRC); or usual supportive care (UC).

MAIN OUTCOME MEASURES: Dietary fat, complex carbohydrates, fiber, and body mass were measured.

STATISTICAL ANALYSIS: In addition to descriptive statistics, analysis of variance was conducted to test for differences according to intervention group.

RESULTS: Of the 157 women with complete dietary data at baseline, 149 had complete data immediately postintervention (at 4 months) and 146 had complete data at 1 year. Women randomized to NEP (n = 50) experienced a large reduction in fat consumption (5.8% of energy as fat) at 4 months and much of this reduction was preserved at 1 year (4.1% of energy) (both P < .0002) vs no change in either SRC (n = 51) or UC (n = 56). A 1.3-kg reduction in body mass was evident at 4 months in the NEP group (P = .003) vs no change in the SRC and UC groups. Women who had higher-than-average expectations of a beneficial effect of the intervention experienced larger changes.

APPLICATIONS: Dietitians' use of group nutrition interventions appear to be warranted. Increasing their effectiveness and maintaining high levels of adherence may require additional support, including the involvement of significant others, periodic individual meetings, or group booster sessions.