(P16-001-23) Subjective Appetite Responses to a 4-week High-Fiber Diet

Objectives: One potential mechanism by which dietary fiber reduces obesity is through enhanced satiety. To test the effects of high-fiber (HiFi) on satiety, we hypothesized that in adult men and women, a HiFi compared to a low-fiber (LowFi) diet will significantly increase subjective fullness ratings while decreasing hunger, prospective consumption and desire to eat ratings.

Methods: Overweight/obese adults, were randomly assigned to consume a standard diet consisting of 25g/d (HiFi) or 5g/d (LowFi) of added pea fiber for 4 weeks (LowFi: n=10, BMI 29.2 ± 2.5 kg/m², 32.0 ± 10.9 y; HiFi: n=10, mean ±SD, BMI 30.0 ± 2.6 kg/m², 32.0 ± 10.3 y). At baseline (visit 1) and after 4 weeks (visit 2) on the LowFi or HiFi diet, subjects completed a meal test challenge lasting 4h, during which fasting and postprandial subjective appetite responses were assessed by rating on a 100 mm visual analogue scale. The total area under the curve was calculated for appetitive responses. A mixed model repeated measures ANOVA and paired t-tests were conducted.

Results: Preliminary findings indicate a significant postprandial time course effect for all 4 appetitive responses assessed (p < 001). It was only for fullness that there was a significant main effect of visit for total AUC (p=0.003), AUC at first 120 min (p=0.030) and AUC at last 120 min (p < 0.001). Mean fullness AUC for LowFi was 8093.7±1486.6 and 11648.7±1726.4; and HiFi was 9439.5±1090.0 and 12079.1±1790.3 mm x 240min for visits 1 and 2 respectively for both treatment groups. For total AUC, fullness was significantly higher at visit 2 vs 1 within the LowFi group (p=0.014) while marginally higher at visit 2 vs 1 within the HiFi group (p=0.058). Within the last 120 minutes, fullness AUC was significantly higher at visit 2 vs 1 in both the LowFi and HiFi groups (p=0.016 and 0.005 respectively).

Conclusions: Consuming 25g/day of added pea fiber for 4 weeks did not influence hunger, prospective consumption and desire to eat but increased fullness AUC over time. Consumption of 5g/day of added pea fiber similarly increased fullness AUC over time, a finding that may be attributable to the latter group having a much lower fullness AUC during the baseline testing.

Funding Sources: University of Missouri and NIH-K01- NHLBI