Changes to dietary intake during a 12-week commercial web-based weight loss program: a randomized controlled trial

The primary aim of this secondary analysis was to compare changes in dietary intake among participants randomized to two versions of a 12-week commercial web-based weight loss program (basic or enhanced) with a waiting-list control. An additional investigation compared changes in dietary intake of successful participants (weight loss ≥5%) with those not successful.

Dietary intake was assessed at baseline and 12 weeks using a validated 120-item semiquantitative food frequency questionnaire. Adults (n=268, 60% female participants, body mass index 32.1 ± 3.9) classified as plausible reporters of energy intake were included in the analyses. Analysis of covariance with baseline observations carried forward for drop-outs (n=38) was used.

The basic and enhanced groups significantly increased their percentage of energy contribution from fruits and reduced energy-dense, nutrient-poor foods compared with controls (P<0.001). Successful participants (n=49) reported superior improvements in dietary intake including greater reductions in the mean daily energy intake (P<0.001), the percentage of energy from energy-dense, nutrient-poor foods (-12.0% E vs -4.3% E, P<0.001) and greater increases in the energy contribution from fruits (P<0.001), vegetables (P=0.003) and breads/cereals (P=0.02).

Use of a commercial web-based weight loss program facilitated some improvements in the dietary intake. The enhanced web-based tools appeared not to have generated greater improvements in reported dietary intake, compared with the basic or control groups. Those who achieved a weight loss of ≥5% improved their dietary intake in line with the program recommendations and dietary guidelines. Further research to determine web-based components that may improve success and the reasons why programs are successful for some participants is required.