Research

Energy balance

Long-term weight loss (2 years) is equivalent across diets emphasizing different macronutrients (low/high fat, average/high protein, low/high carbohydrate) when caloric intake is reduced and adherence is supported.

To lose weight, focus on creating a consistent caloric deficit rather than obsessing over whether your diet is high-protein, low-carb, or low-fat. This study shows that if you can adhere to a reduced-calorie diet (approx. 750 kcal deficit/day) for two years, you will lose a similar amount of weight regardless of the macronutrient breakdown. Use behavioral tools like food diaries and regular check-ins to maintain adherence, as attendance and consistency were the strongest predictors of success.

StrongRefutesVERY_HIGH confidence
Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize.
Frank M. Sacks et al. · New England Journal of Medicine · 2009

Why this rating

Large randomized clinical trial (n=811), 2-year duration, factorial design, intention-to-treat analysis, published in NEJM.

Source

Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates

Frank M. Sacks et al. · New England Journal of Medicine · 2009

DOI 10.1056/nejmoa0804748

rct · n=811Cited 1,953×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →