TOPLINE

Carbohydrate restriction to less than 45% of total daily energy intake likely offered modest benefits for weight management and certain cardiometabolic risk factors in adults with overweight or obesity, according to a meta-analysis of 23 randomized controlled trials.

METHODOLOGY

• As obesity rates rise, carbohydrate restriction has reemerged as a popular weight-loss strategy, but it isn’t clear whether stricter carb cutting offers added benefits beyond reducing low-quality carbs. 
• Researchers conducted a systematic review and meta-analysis of 23 randomized controlled trials published from 2010 to 2025, comparing carbohydrate-restricted diets (less than 45% of total daily energy intake) with higher-carbohydrate approaches in adults with overweight or obesity and no other established disease. 
• The 23 trials were represented in 28 articles, with intervention durations ranging from 4 weeks to 36 months. 
• Studies were required to report energy and carbohydrate intakes at both baseline and the end of intervention. Carbohydrate restriction was classified as moderate (26% to < 45% of total daily energy intake), low (10% to < 26%), or very low (less than 10%); most studies compared moderately carbohydrate-restricted diets with higher-carbohydrate diets. 
• Primary outcomes included anthropometric measures (body weight, BMI, waist circumference, fat mass, and lean body mass) and glycemic outcomes (fasting blood glucose and A1c).

TAKEAWAY

• In an analysis of 22 trials, carbohydrate restriction resulted in a significant decrease in body weight (mean difference [MD], -1.32 kg; 95% CI, -2.03 to -0.61) compared with higher-carbohydrate intake, with certainty of evidence rated as moderate. 
• Participants following carbohydrate-restricted diets experienced reductions in waist circumference (MD, -0.89 cm; 95% CI, -1.44 to -0.34; 13 trials) and fat mass (standardized MD, -0.29; 95% CI, -0.48 to -0.10; 16 trials) than those following higher-carbohydrate diets. 
• Carbohydrate restriction also reduced A1c, triglycerides, and systolic blood pressure than higher-carbohydrate diets; fasting blood glucose improved modestly as well, though the effect was borderline significant. Carbohydrate restriction showed no clear effect on total cholesterol, low-density lipoprotein cholesterol, or high-density lipoprotein cholesterol concentrations.
• Meta-regression analyses showed that differences in carbohydrate intake between groups at the end of the intervention had no significant effect on any measured outcomes, suggesting that the degree of carbohydrate restriction within the studied range may not substantially influence results.

IN PRACTICE

“(This study) demonstrates that carbohydrate-restricted dietary patterns likely provide modest benefits for weight management and certain cardiometabolic risk factors in adults with overweight or obesity. Registered dietitian nutritionists can leverage this evidence to inform evidence-based nutrition care for adults with overweight or obesity,” the authors of the study wrote.

SOURCE

The study was led by Matthew Landry, PhD, RDN, DipACLM, Department of Population Health & Disease Prevention, Joe C. Wen School of Population & Public Health, University of California, Irvine. It was published online in the Journal of the Academy of Nutrition and Dietetics.

LIMITATIONS

The study faced substantial heterogeneity in how carbohydrate restriction was defined and implemented across studies, with discrepancies between prescribed and self-reported carbohydrate intake being common, particularly in longer-duration studies. The quality of included studies varied considerably, with only five studies showing a low risk for bias. Many of the trials were short, with some lasting just 4 weeks, making it difficult to understand how well these diets work over the long term. The review focused specifically on adults with overweight or obesity and no other established disease, which may limit the generalizability of the findings to individuals with existing comorbidities.

DISCLOSURES

This systematic review and meta-analysis received funding from the Academy of Nutrition and Dietetics. The authors reported no conflicts of interest to disclose.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.