Time-Restricted Eating and HIIT Show No Significant Impact on Gestational Diabetes Risk: Study
A new clinical trial published in the journal of BMJ revealed that time-restricted eating and HIIT did not significantly change the risk of developing gestational diabetes mellitus (GDM) among pregnant individuals. The study was conducted at a university hospital in Norway and involved 167 participants recruited between October 2020 and May 2023. All participants had at least one known risk factor for GDM and were planning pregnancy.
The participants were randomly assigned to either a lifestyle intervention group or a standard care control group. The intervention included a structured exercise program designed to achieve a target of at least 100 weekly points using the personal activity intelligence (PAI) system. Additionally, these participants were asked to adopt time-restricted eating, confining all daily energy intake to within 10 hours on at least 5 days per week. The intervention began prior to conception and continued through pregnancy.
The trial’s primary outcome was the 2-hour plasma glucose concentration during an oral glucose tolerance test (OGTT) at 28 weeks’ gestation. Of the 167 women enrolled, 111 became pregnant (56 in the intervention group and 55 in the control group). One intervention participant was excluded due to a diagnosis of prepregnancy diabetes, and one control participant was excluded due to a twin pregnancy.
These results showed no statistically significant difference in glucose levels between the 2 groups. The mean difference in 2-hour plasma glucose was 0.48 mmol/L (95% confidence interval −0.05 to 1.01, P=0.08), falling short of clinical significance.
During the prepregnancy phase, 37% of the intervention group (31 of 83 participants) met the prespecified adherence criteria. Among those who conceived, adherence improved slightly, with 44% (24 of 55) maintaining the program. On average, participants achieved an eating window of 9.9 hours per day and scored 111 weekly PAI points before conception. However, both adherence to restricted eating and exercise intensity declined once pregnancy began.
While exercise and time-restricted eating are known to improve metabolic health in the general population, their translation into measurable improvements in pregnancy-specific glucose regulation remains uncertain. This emphasize the need for further research into tailored interventions that can sustain adherence during pregnancy.
Source:
Sujan, M. J., Skarstad, H. M., Rosvold, G., Fougner, S. L., Follestad, T., Salvesen, K. Å., & Moholdt, T. (2025). Time restricted eating and exercise training before and during pregnancy for people with increased risk of gestational diabetes: single centre randomised controlled trial (BEFORE THE BEGINNING). BMJ (Clinical Research Ed.), 390,. https://doi.org/10.1136/bmj-2024-083398
