Whole grains, fruits, nonstarchy veggies help prevent weight gain

An increase in dietary glycaemic index, glycaemic load, and amounts of starch, added sugars, refined grains, and starchy vegetables result in more weight gain in midlife, suggests a study. On the other hand, greater intake of fibre, whole grains, fruits, and nonstarchy vegetables is associated with better weight control.

“The findings of this study highlight the potential importance of carbohydrate quality and source for long-term weight management, especially for people with excessive body weight,” the researchers said. “Limiting added sugar, sugar sweetened beverages, refined grains, and starchy vegetables in favour of whole grains, fruit, and nonstarchy vegetables may support efforts to control weight.”

This prospective cohort study included 136,432 men and women aged ≤65 years and free of diabetes, cancer, cardiovascular disease, respiratory disease, neurodegenerative disorders, gastric conditions, chronic kidney disease, and systemic lupus erythematosus before baseline. Participants were identified from the Nurses’ Health Study (NHS), NHS II, and the Health Professionals Follow-Up Study (HPFS).

In the final analyses, 46,733 women in the NHS, 67,186 women in the NHS II, and 22,524 men in the HPFS were included. Participants gained an average of 1.5 kg (5th to 95th centile, ‒6.8 to 10.0) every 4 years, corresponding to 8.8 kg over 24 years. [BMJ 2023;382:e073939]

Carbohydrate quality

Increases in glycaemic index and glycaemic load resulted in weight gain in both men and women. For instance, a 100-g/day increase in starch or added sugar led to a 1.5-kg and 0.9-kg weight gain over 4 years, respectively, while a 10-g/day increase in fibre resulted in a 0.8-kg less weight gain.

Greater consumption of carbohydrates from whole grains (0.4 kg less weight gain per 100-g/day increase), fruit (1.6 kg less weight gain per 100-g/day increase), and nonstarchy vegetables (3.0 kg less weight gain per 100-g/day increase) showed an inverse relation with weight gain.

In contrast, individuals with higher intake from refined grains (0.8 kg more weight gain per 100-g/day increase) and starchy vegetables (eg, peas, corn, and potatoes; 2.6 kg more weight gain per 100-g/day increase) gained more weight.

“These findings support the potential importance of carbohydrate quality and source for long-term weight control,” the researchers said.

Whole grains

Substitution analyses also revealed that replacing refined grains, starch vegetables, and sugar-sweetened beverages with equal servings of whole grains, fruit, and nonstarchy vegetables produced lesser weight gain over time.

“The magnitude of these associations was stronger among participants with overweight or obesity compared with those with normal weight (p<0.001 for interaction),” said the researchers, noting that these associations were more evident among women.

An earlier study also reported on the benefits of whole grain consumption, while previous research on fruit intake in relation to weight gain showed mixed results. [PLoS Med 2015;12:e1001878; Nutrients 2019;11:1245; J Obes 2013;2013:525161; Am J Clin Nutr 2012;95:184-193]

“Our findings for starchy vegetables raise concerns about the current recommendation of the Dietary Guidelines for Americans to increase consumption of all types of vegetables, specifically including starchy vegetables,” the researchers said. [https://www.dietaryguidelines.gov/sites/default/files/2021-03/Dietary_Guidelines_for_Americans-2020-2025.pdf]