WEIGHT management during pregnancy, particularly in women with gestational diabetes and elevated body mass index (BMI), is an area of growing clinical interest. While reduced-energy diets have proven beneficial for individuals with type 2 diabetes, their safety and effectiveness in pregnant populations have not been well studied. This study explored whether implementing a reduced-energy diet during pregnancy could influence maternal weight and neonatal outcomes in women diagnosed with gestational diabetes. A key finding from this trial is that a 1,200 kcal/day diet was found to be safe but did not significantly impact maternal weight or birth weight.
The research was conducted as a multicentre, parallel-group, randomised controlled trial, involving women with singleton pregnancies, diagnosed with gestational diabetes, and a BMI of 25 kg/m² or greater. Participants were randomly allocated in a 1:1 ratio to either a standard-energy control diet (2,000 kcal/day) or a reduced-energy intervention diet (1,200 kcal/day), with diet boxes supplied weekly. The dietary intervention began at 29 weeks of gestation and continued until delivery. Randomisation was stratified by centre, and both participants and the research team remained blinded throughout the study period. Primary outcomes assessed were maternal weight change up to 36 weeks and standardised birth weight of the offspring.
A total of 425 women were enrolled, with 211 receiving the control diet and 214 assigned to the intervention. The results showed no statistically significant difference in maternal weight change at 36 weeks between groups (intervention effect −0.20 kg; 95% CI −1.01–0.61; p>0.1), nor in standardised birth weight (intervention effect 0.005; 95% CI −0.19–0.20; p>0.1). These findings indicate that the reduced-energy diet did not confer measurable benefits in the primary clinical outcomes studied.
While the dietary intervention was confirmed to be safe, the study has limitations. The late gestational age at intervention onset may have limited potential effects, and adherence to dietary plans was not detailed. For clinical practice, this trial suggests that routine energy restriction from 29 weeks may not yield improvements in weight or neonatal outcomes in women with gestational diabetes, though safety reassurance supports further exploration of nutritional strategies earlier in pregnancy.
Reference
Kusinski LC et al. Reduced-energy diet in women with gestational diabetes: the dietary intervention in gestational diabetes DiGest randomized clinical trial. Nat Med. 2025;31(2):514-23
