Adherence to a walnut-based low-carbohydrate diet (w-LCD) results in substantially faster and greater fat reduction over time among individuals with central obesity compared with a high-carbohydrate, low-fat diet (HCD), according to a study.
This finding provides “a solid evidence-based foundation for dietary management in people with central obesity,” said the researchers, who conducted a 12-week prospective randomized controlled trial.
Eighty eligible participants with central obesity were randomly allocated to either the w-LCD (n=40) or HCD (n=40) group. The 2021 Guidelines for Medical Nutrition Therapy of Overweight and Obesity formed the HCD program. Based on the HDC program, the w-LCD regimen was created by replacing 150 g/day of staple food with walnuts rich in healthy fat.
The research team assessed visceral fat area (VFA), trunk-to-leg fat ratio (TLR), and waist-to-hip ratio (WHR) at baseline and 12 weeks.
Significant group‒time interaction effects were observed for TLR (η²=0.071; p=0.039) and VFA (η²=0.093; p=0.014), with moderate effect, and for BMI (η²=0.168; p=0.001), with large effect. These findings confirmed a statistically superior trend with w-LCD in reducing TLR, VFA, and BMI over 12 weeks compared with HCD. [Asia Pac J Clin Nutr 2026;35:766-778]
“In addition, there was a tendency of significant differences in the group‒time interaction effect of WHR (η²=0.052; p= 0.072), indicating that w-LCD has the tendency to potentially reduce WHR,” the researchers said.
Between-group comparisons showed no significant differences in TLR, VFA, and BMI at 12 weeks, but within-group comparison revealed reductions with large effect on TLR (η²=0.174; p=0.001), VFA (η²=0.393; p<0.001), and BMI (η²=0.399; p<0.001) in the w-LCD group over time.
“Although we found no significant difference in BMI between the two groups at 12 weeks, which is consistent with the study by Guo and colleagues, both low-carbohydrate and low-fat diets led to short-term weight loss in [people with overweight or obesity] with impaired glucose regulation using generalized estimating equations,” the researchers said.
“This indicates that the BMI in the w-LCD group decreased much more over the course of the study, which may be related to the restriction of carbohydrate intake,” they added.
Previous studies
A meta-analysis of randomized controlled trials revealed a significant BMI reduction with LCD (standardized mean difference [SMD], ‒1.44, 95 percent confidence interval [CI], ‒2.70 to ‒0.61). [Diabetes Obes Metab 2022;24:1458-1468]
In another meta-analysis, the investigators reported a significant decrease in BMI with walnut intake of up to 35 g/day (p=0.041). [Complement Ther Med 2020;50:10239]
“Therefore, increasing walnut intake along with LCD may lead to more reduction in BMI,” the investigators said.
“Although [the current] study did not find that w-LCD could effectively reduce body fat percentage, there was a trend of its decrease,” they added.
On the other hand, a network meta-analysis by Ruben and colleagues observed a significant reduction in body fat percentage following walnut intake (SMD, ‒0.85, 95 percent CI, ‒1.20 to ‒0.49). [Nutrients 2021;13:2251]
“BMI and body fat percentage, as concise and effective indicators to measure obesity, can better reflect the degree of obesity,” according to the investigators. [Eur J Clin Nutr 2012;66:926-931; Br Med Bull 2013;105:185-199]
“These indicators are associated with the blood pressure variability index, which increases with the degree of obesity and thus increases the risk of cardiovascular disease,” they added. [Chin J Hypertens 2021;29:1083-1091]