A diet emphasizing high-fiber foods during pregnancy decreases gestational weight gain and fat accrual: results from a pilot trial.

Excessive gestational weight gain (GWG) is linked to poor pregnancy outcomes and increased maternal obesity. Current interventions moderately reduce GWG, but have limited impact on maternal health. Dietary fiber supports weight management and diet quality outside of pregnancy, yet its effects during pregnancy remain unclear. We hypothesized that a high fiber (HFib) intervention would reduce GWG, decrease fat accrual, and improve diet quality compared with standard prenatal care. In this randomized controlled pilot trial, the HFib group completed an 18-week intervention beginning at 12 to 20 weeks gestation, which included behavioral education and daily HFib snacks. Of n = 51 participants randomized, n = 31 were included in the final analysis (HFib: n = 16, usual care: n = 15). GWG, body composition, dietary intake, and diet quality were assessed at baseline and intervention end. Total GWG was lower in the HFib group (mean difference -5.5 kg, P = .029) compared to controls, and by the end of the intervention, the HFib group also showed smaller increases in body fat percentage (1.6% vs 4.5%, P = .033) and fat mass (mean difference -2.7 kg, P = .029). Fiber intake increased from 21.8 ± 7.5 to 35.1 ± 7.4 g/d in the HFib group, while the usual care group remained near 19 g/d. Diet quality improved in the HFib group (+7.6 points) and declined in usual care (P = .003). In conclusion, the HFib intervention, combining HFib snacks and behavioral education, significantly increased fiber intake and improved adherence to a food-based HFib dietary pattern. These findings suggest the approach is feasible and may help reduce GWG and fat accrual. This trial was registered at clinicaltrials.gov (NCT04868110).