The Impact of a Long-Term Reduction in Dietary Energy Density on Body Weight Within a Randomized Diet Trial

We examined the effect of dietary energy density change on body weight in participants of a randomized trial. Intervention participants markedly increased fruit and vegetable intake while reducing energy intake from fat. Participants were 2,718 breast cancer survivors, aged 26–74 yr, with baseline mean body mass index of 27.3 kg/m^{m 2} (SD = 6.3). We assessed dietary intake by sets of four 24-h dietary recalls and validated with plasma carotenoid concentrations. Weight and height were measured at baseline, 1 yr, and 4 yr. Dietary energy density was calculated using food but excluding beverages. Intervention participants significantly reduced dietary energy density compared to controls and maintained it over 4 yr—both in cross-sectional ( P m < 0.0001) and longitudinal (Group m × Time interaction, P m < 0.0001) analyses. Total energy intake or physical activity did not vary between groups. The intervention group had a small but significant weight loss at 1 yr (Group m × Time interaction, P m < 0.0001), but no between-group weight difference was observed at 4 yr. Our study showed that reducing dietary energy density did not result in a reduction in total energy intake and suggests that this strategy alone is not sufficient to promote long-term weight loss in a free-living population.