What this means
Sixty-one older men followed a fasting diet for four weeks and took protein, leucine, or a placebo. All groups lost weight and improved in several health measures. The extra protein and leucine did not add measurable benefit beyond that.
Plain-English summary written by an AI model from the abstract. The original is below.
- Who it was tested in
- 61 older men in a randomized trial, four weeks
- Kind of research
- A clinical trial in people
The science
- Original title
- Effects of Body-Mass-Scaled Protein and Leucine Supplementation on Body Composition and Cardiometabolic Blood Markers During Weight Loss in Older Men-A Randomized Controlled Trial.
- Authors
- Pang BWJ, Yang Y, Cheon BK
- Journal
- Nutrients
- Published
- Oct 16, 2026
- Study type
- Clinical trial · in humans
- PMID
- 42884706 ↗
Abstract
Background: Overweight and obesity are burgeoning health epidemics. Diets including alternate-day fasting (ADF) promote weight loss but risk significant muscle loss, posing health implications to seniors at risk of sarcopenia. Leucine, the key muscle protein synthesis (MPS) driver, effectively stimulates MPS with lower calorie intake than protein. However, the effects of body-mass-scaled protein and leucine intakes are unclear. Objectives: To evaluate body-mass-scaled leucine or protein supplementation on body composition, sarcopenic, and cardiometabolic markers in older men during ADF. Methods: Sixty-one older men (BMI ≥ 23.0 kg/m2) underwent 28 days of ADF, randomized across three calorie-matched supplement groups: Control (C: 0.0 g/kg protein, 0.0 g/kg leucine), Leucine (L: 0.0 g/kg protein, 0.08 g/kg leucine), or Protein (P: 0.4 g/kg protein, 0.04 g/kg leucine), consuming three doses on feeding days and one on fasting days. Dual-energy X-ray absorptiometry, sarcopenic metrics, and blood markers (blood pressure, lipid panels, diabetic profiles) were measured. Results: There were no significant interactions (p > 0.05) in body composition, sarcopenic or health outcomes, except for diastolic blood pressure (p = 0.016) and HDL cholesterol (p = 0.013). There were significant main effects of time (p ≤ 0.05) with reductions in all body composition measures (excluding bone mineral density, p = 0.274), systolic blood pressure and lipid profiles (total and LDL cholesterol, total/HDL cholesterol ratio, triglycerides), and improvements in all muscle strength and functional sarcopenic outcomes. Conclusions: Dietary interventions alone that increase leucine and/or protein intake did not result in additional measurable improvements during this four-week intervention on body composition, sarcopenic, and cardiometabolic outcomes during weight loss.
Pang BWJ, Yang Y, Cheon BK Effects of Body-Mass-Scaled Protein and Leucine Supplementation on Body Composition and Cardiometabolic Blood Markers During Weight Loss in Older Men-A Randomized Controlled Trial. Nutrients. 2026. doi:10.3390/nu18193255. PMID: 42884706. https://pubmed.ncbi.nlm.nih.gov/42884706/
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