Nutritional implications of reduced-fat food use by free-living consumers

The nutritional implications of the purchase and consumption of reduced-fat foods at home were assessed in normal-weight, free-living consumers in a 6-week intervention study. Control (n = 14) and experimental (n = 15) subjects kept 4-day weighed food diaries to establish energy and macronutrient intake at baseline and experimental weeks 2, 4 and 6. The control group continued their habitual diet throughout the study whereas the experimental group used reduced-fat foods ad libitum in place of the traditionally high-fat counterparts that they usually consumed. All subjects purchased the majority of their groceries from the same food store and were reimbursed for a proportion of their grocery bill. Repeated-measures analysis of variance indicated that the experimental group, compared to the control group, significantly reduced their percentage of energy from fat (from 38.3 +/- 1.8 to 30.4 +/- 1.7), but increased the percentage of energy from protein (p = 0.06) and carbohydrate (p = 0.019) such that changes in total energy intake were not statistically significantly different between conditions. Nevertheless, the experimental group lost 1.1 kg (while the control group gained 0.4 kg) in the first 4 weeks of the study, consistent with the observed reduction in energy intake, though no further body weight changes were seen in week 6. This study suggests that although use of reduced-fat foods may have short-term effects on energy balance, long-term sustained reduction in energy intake may be limited if this dietary strategy is used in isolation.