Association between low-carbohydrate diet and low-fat diet scores and sarcopenia as determined by dual-energy X-ray absorptiometry: a cross-sectional study

Abstract Objective This study aimed to investigate the effects of low-carbohydrate diets (LCD) and low-fat diets (LFD) on sarcopenia, as well as the source and quality of nutrients, to provide strong support for the development of a more scientifically based dietary guidance scheme. Methods The data of this study came from the National Health and Nutrition Examination Survey (NHANES). LCD and LFD scores were calculated based on macronutrient energy proportions. Logistic regression, isoenergetic substitution models were used to evaluate associations with sarcopenia, defined by dual-energy X-ray absorptiometry (DXA). Results A total of 1,745 participants were included in this study, with a mean age of 38.71 ± 0.46 years and a mean body mass index (BMI) of 28.87 ± 0.26 kg/m². After adjusting for covariates, the highest tertiles of overall LCD and healthful LCD scores were associated with a significantly lower risk of sarcopenia, with odds ratios (OR) of 0.48 (95% CI: 0.24–0.96) and 0.51 (95% CI: 0.32–0.81), respectively, compared with the lowest tertiles. In comparison, the highest tertile of the total LFD was associated with a 78% higher risk of sarcopenia (OR = 1.78; 95% CI: 1.03–3.11). Furthermore, replacing 5% of energy from carbohydrates with protein or fat, and with plant protein or unsaturated fat, was associated with reduced sarcopenia risk, with OR of 0.86 (95% CI: 0.74–0.99) and 0.80 (95% CI: 0.65–0.99), respectively. Conclusion In this cross-sectional study, higher overall and healthful LCD scores are associated with a lower risk of sarcopenia, whereas higher overall and unhealthful LFD scores are associated with an increased risk. These findings suggest that the relationships between LCD, LFD, and sarcopenia may depend not only on the quantity of macronutrients but also on their dietary sources.