Low-carbohydrate diets emphasizing healthy, plant-based sources are associated with slower long-term weight gain.

In Boston, MA, a study reveals that low-carbohydrate diets emphasizing healthy choices, such as plant-based proteins, fats, and whole grains, are linked to slower long-term weight gain compared to those relying on animal proteins, fats, and refined starches, according to a new investigation led by Harvard T.H. Chan School of Public Health.

“Our study goes beyond the simple question of, ‘To carb or not to carb?’” said lead author Binkai Liu, research assistant in the Department of Nutrition. “It dissects the low-carbohydrate diet and provides a nuanced look at how the composition of these diets can affect health over years, not just weeks or months.”

While many studies have shown the benefits of cutting carbohydrates for short-term weight loss, little research has been conducted on low-carbohydrate diets’ effect on long-term weight maintenance and the role of food group quality.

Making use of information from the Health Professionals Follow-up Study, Nurses’ Health Study, and Nurses’ Health Study II, the investigators analyzed the diets and weights of 123,332 healthy adults from as early as 1986 to as recently as 2018. Each participant provided self-reports of their diets and weights every four years.

 The researchers scored participants’ diets based on how well they adhered to five categories of low-carbohydrate diets:

• Total low-carbohydrate diet (TLCD), emphasizing overall lower carbohydrate intake.
• Animal-based low-carbohydrate diet (ALCD), emphasizing animal-based proteins and fats.
• Vegetable-based low-carbohydrate diet (VLCD), emphasizing plant-based proteins and fats.
• Healthy low-carbohydrate diet (HLCD) emphasizing plant-based proteins, healthy fats, and fewer refined carbohydrates.
• An unhealthy low-carbohydrate diet (ULCD) emphasizes animal-based proteins, unhealthy fats, and carbohydrates from unhealthy sources such as processed bread and cereals.

The study found that diets comprised of plant-based proteins, fats, and healthy carbohydrates were significantly associated with slower long-term weight gain. On average, participants who increased their adherence to TLCD, ALCD, and ULCD, gained more weight than those who increased their adherence to HLCD over time.

 These associations were most pronounced among younger participants (<55 years old), overweight or obese, and less physically active. The results for the vegetable-based low carbohydrate diet were more ambiguous: Data from the Nurses’ Health Study II showed an association between higher VLCD scores and less weight gain over time, while data around VLCD scores from the Nurses’ Health Study and Health Professionals Follow-up Study were more mixed.

“The key takeaway here is that not all low-carbohydrate diets are created equal when it comes to managing weight in the long-term,” stated Associate Professor Qi Sun works at the Department of Nutrition. and senior author. “Our findings could shake up the way we think about popular low-carbohydrate diets and suggest that public health initiatives should continue to promote dietary patterns that emphasize healthful foods like whole grains, fruits, vegetables, and low-fat dairy products.”

Other Harvard Chan authors contained Molin Wang, associate instructor in the Departments of Epidemiology and Biostatistics, and Yang Hu, research scientist; Sharan Rai, postdoctoral research fellow; and Frank Hu, professor in the Department of Nutrition.

The study was funded by research National Institutes of Health grants: P01 CA87969, R01 CA186107, U01 CA176726, U01 CA167552, UM1 CA186107HL034594, R01 HL035464, R01 HL60712, R01 DK120870, R01 DK126698, R01 DK119268, U2C DK129670, DK119268, R01 ES022981, and R21 AG070375.

“Low-Carbohydrate Diet Macronutrient Quality and Weight Change,” Binkai Liu, Yang Hu, Sharan K. Rai, Molin Wang, Frank B. Hu, Qi Sun, JAMA Network Open, December 27, 2023, doi: 10.1001/jamanetworkopen.2023.49552

conclusion

In conclusion, embracing low-carbohydrate diets prioritizing wholesome, plant-based sources is linked to a notable decrease in long-term weight gain. This underscores the significance of adopting sustainable dietary practices, aligning with health and weight management goals. 

The emphasis on plant-derived carbohydrates contributes to weight control and promotes overall well-being, affirming the value of balanced and mindful nutritional choices.

FAQ

Why do low-carb diets produce rapid weight loss?

In general, when eating less carbs, one should consume more fat and protein as macronutrients to make up for the loss of carbohydrates. One theory explaining why low-carb diets result in quicker weight reduction than other diets is because fats and protein boost satiety and reduce the likelihood of concurrent hypoglycemia.

Does a low-carb diet help the heart?

According to research, if you choose your protein and fat from healthful sources, a diet with a fairly low carbohydrate count can benefit your heart. Lower carbohydrate diets and heart disease were studied in a 20-year prospective research involving 82,802 women; lower carbohydrate diets and the risk of diabetes were studied in a follow-up study.

Are low-carbohydrate diets good for women?

Women who followed low-carb diets rich in vegetable sources of fat or protein had around a lowered incidence of type 2 diabetes by 20% as well as a 30% lower risk of heart disease (4) compared to those who ate high-carb, low-fat diets ( 34).