This Low-Carb Diet Can Lead to the Most Weight Loss, Harvard Study Finds

It's a new year, and you're probably looking for ways to have a better diet. New research from the Harvard T.H. Chan School of Public Health shows that low-carbohydrate diets composed of plant-based proteins and fats with healthy carbohydrates such as whole grains are associated with slower long-term weight gain and better than low-carb diets comprised mostly of animal proteins and fats with unhealthy carbohydrates like refined starches.

"Our study goes beyond the simple question of, 'To carb or not to carb?'" said lead author Binkai Liu, a 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," Liu added.

Impact of 5 Low-Carb Diets

The study delved into the impact of five distinct low-carbohydrate diets on sustained weight change. Over the course of several decades, data from the Nurses' Health Study, Nurses' Health Study II, and Health Professionals Follow-up Study was scrutinized, involving 123,332 healthy adults from as early as 1986 to as recently as 2018.

The five categories of low-carbohydrate diets scrutinized were defined as follows:

1. Total Low-Carbohydrate Diet (TLCD): Focused on an overall reduction in carbohydrate intake.

2. Animal-Based Low-Carbohydrate Diet (ALCD): Emphasized animal-based proteins and fats.

3. Vegetable-Based Low-Carbohydrate Diet (VLCD): Centered around plant-based proteins and fats.

4. Healthy Low-Carbohydrate Diet (HLCD): Prioritized plant-based proteins, healthy fats, and limited refined carbohydrates.

5. Unhealthy Low-Carbohydrate Diet (ULCD): Emphasized animal-based proteins, unhealthy fats, and carbohydrates sourced from processed items.

The findings indicated that diets predominantly composed of plant-based proteins, healthy fats, and wholesome carbohydrates correlated with a slower rate of long-term weight gain.

Conversely, individuals who increased adherence to TLCD, ALCD, and ULCD experienced a greater tendency to gain weight over time. This connection was especially noticeable among participants under the age of 55, those categorized as overweight or obese, and those with lower levels of physical activity.

While the outcomes of the vegetable-centric low-carbohydrate diet (VLCD) exhibited some variability, as indicated by the Nurses' Health Study II linking higher VLCD scores to decreased long-term weight gain, the research implies that the effectiveness of low-carbohydrate diets in maintaining weight loss is not consistent across the board.

'Shake Up'

Senior author Qi Sun, an associate professor in the Department of Nutrition, underscored the significance of these findings, noting that they challenge prevailing notions about popular low-carbohydrate diets.

The study advocates for public health initiatives to continue promoting dietary patterns prioritizing healthful foods, including whole grains, fruits, vegetables, and low-fat dairy products.

"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," Sun said in a statement.

The findings of the study were published in JAMA Network Open.