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

Abstract

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.

ACKNOWLEDGMENTS

The authors thank Christine Hayes for her editorial support. This study was initiated with the support of the Walton Family Foundation and continued with funding from National Cancer Institute (NIH) Grant CA 69375. Some of the data were collected from General Clinical Research Centers, NIH grants M01–RR00070, M01–RR00079, and M01–RR00827.

Notes

^aAbbreviations are as follows: BMI, body mass index; MET, metabolic equivalent tasks; min, minute; SE, standard error of the mean. Mean and standard error for continuous variables and frequency for categorical variables are presented.

^bMean ± SE.

^a n = 2,713 (intervention and control group combined). 24-h dietary recalls were used to obtain dietary information via telephone interview. Abbreviations are as follows: SEM, standard error of the mean; BMI, body mass index; ref, reference.

*indicates significant differences.

^bOne-way analysis of variance examined group differences.

^an = 2,713 (intervention and control group combined)

*

†) are significantly different (P <0.05). 1 kcal = 4.18 kJ. Abbreviation is as follows: METs, metabolic equivalent tasks.

^bMean ± standard error of the mean.

^cSum of METs assigned as 2 METs/min of casual strolling, 3 METs/min of mild activity or average walking, 4 METs/min of fast walking, 5 METs/min of moderate activity, 6 METs/min of very fast walking, 8 METs/min of strenuous activity.

^aMixed effect models were used to examine difference of change between groups from baseline.

*P < 0.05;

**P < 0.0001: computed for testing Group × Time interaction for each variable. Abbreviations are as follows: SEM, standard error of the mean; METs, metabolic equivalent tasks.

^b1 kcal = 4.18 kJ.

^cSum of METs assigned as 2 METs/min of casual strolling, 3 METs/min of mild activity or average walking, 4 METs/min of fast walking, 5 METs/min of moderate activity, 6 METs/min of very fast walking, 8 METs/min of strenuous activity.