A recent study conducted by Harvard TH Chan School of Public Health has found that low-carb diets, mainly consisting of plant-based proteins and healthy carbohydrates such as whole grains, are associated with slower long-term weight gain compared to low-carb diets that mainly consist of animal proteins and unhealthy carbohydrates like refined starch.
Published in JAMA Network Open on December 27, 2023, the study challenges the conventional notion of „to carb or not to carb“ and instead looks at the long-term impact of low-carb diets on health.
„Our study goes beyond the simple question of ‚to eat carbs or not‘ and provides a nuanced view of how the composition of these diets over years, rather than weeks or months, can impact health,“ said Binkai Liu, lead author and research associate in the Department of Nutrition.
– Binkai Liu
While many studies have demonstrated the benefits of cutting carbs for short-term weight loss, there has been limited research on the long-term impact of low-carb diets on weight maintenance and the role of food group quality.
The researchers analyzed data from 123,332 healthy adults from 1986 to 2018. Participants reported on their diet and weight every four years, and their adherence to five categories of low-carb diets was evaluated: total low-carb diet (TLCD), animal-based low-carb diet (ALCD), plant-based low-carb diet (VLCD), healthy low-carb diet (HLCD), and unhealthy low-carb diet (ULCD).
The study found that a diet consisting of plant-based proteins and healthy carbohydrates was significantly associated with slower long-term weight gain. Participants who increased their adherence to TLCD, ALCD, and ULCD experienced more weight gain over time compared to those who increased their adherence to HLCD. These associations were most pronounced in younger participants, those who were overweight or obese, and/or less physically active. The results for plant-based low-carb diets were less definitive, with mixed findings from different study groups.
„The key insight here is that not all low-carb diets are equal when it comes to long-term weight control,“ said senior author Qi Sun, associate professor in the Department of Nutrition. „Our results could shift our thinking about popular low-carb diets and suggest that public health initiatives should continue to promote diets that emphasize healthy foods such as whole grains, fruits, vegetables, and low-fat dairy products.“
Other authors from Harvard Chan included Molin Wang, associate professor in the Departments of Epidemiology and Biostatistics; Yang Hu, research scientist; Sharan Rai, postdoctoral fellow; and Frank Hu, professor in the Department of Nutrition.
The study was funded by research grants from the National Institutes of Health: UM1 CA186107, U01 CA176726, U01 CA167552, P01 CA87969, R01 HL034594, R01 HL035464, R01 HL60712, R01 DK120870, R01 DK126698, R01 DK 119268, U2C DK129670, DK119268, R01 ES022981, and R21 AG070375.
Harvard TH Chan School of Public Health
Liu, B., et al. (2023). Low-carb diet macronutrient quality and weight change. JAMA Network Open. doi.org/10.1001/jamanetworkopen.2023.49552.