When it comes to managing gestational diabetes, many women and their doctors are interested in whether a reduced-calorie diet can make a difference. Gestational diabetes affects between 6% and 15% of pregnancies and can increase risks for both mom and baby. While cutting calories has been shown to help those with type 2 diabetes outside of pregnancy, its benefits during pregnancy—particularly for gestational diabetes—have been unclear.
The Study: What Did Researchers Look At?
Researchers from the University of Leicester and the University of Cambridge set out to answer this question. They conducted a large, randomized trial called the “Dietary Intervention in Gestational Diabetes (DiGest)” study, recently published in Nature Medicine. The study included 425 pregnant women with gestational diabetes and a body mass index (BMI) of 25 or higher. Half were given a standard 2,000-calorie diet, while the other half followed a reduced-energy diet of 1,200 calories per day. Both diets offered similar nutrient proportions: 40% carbohydrates, 35% fat, and 25% protein.
What Did They Find?
The key outcomes measured were changes in maternal weight from 29 to 36 weeks of pregnancy and the baby’s birth weight. Surprisingly, the researchers found no significant differences between the two groups for either outcome. This means that, at least when started late in pregnancy, a low-calorie diet didn’t lead to more weight loss for the mothers or lower birth weights for the babies.
However, there were some positive notes: women on the reduced-calorie diet did show improved blood sugar control and were less likely to need long-acting insulin. But when it came to the main clinical goals—maternal weight change and baby weight—the results were a wash. Importantly, the reduced-calorie diet was also found to be safe for both mother and baby.
Why Does This Matter?
These results challenge the idea that a lower calorie diet will always improve pregnancy outcomes in women with gestational diabetes. It’s possible that starting dietary changes earlier in pregnancy or considering other nutritional strategies could make a difference, but for now, the evidence suggests that late-pregnancy calorie restriction alone isn’t enough to boost outcomes.
Bottom Line
A low-calorie diet during the third trimester in women with gestational diabetes appears safe and may help with blood sugar control, but it doesn’t seem to change overall weight outcomes for mom or baby. More research is needed to explore the best timing and types of dietary interventions for this group.
Study details: The paper, “Reduced-energy diet in women with gestational diabetes: the dietary intervention in gestational diabetes DiGest randomized clinical trial,” was authored by researchers including Prof. Claire Meek from the University of Cambridge, and published in Nature Medicine.
