Macro partitioning
Myostatin-activin pathway inhibitors (MAPi), specifically bimagrumab, can reduce fat mass while preserving or increasing lean mass, offering a potential solution to the lean mass loss associated with GLP-1 agonists.
If you are concerned about losing muscle on weight loss drugs, ask your doctor about Myostatin-Activin Pathway Inhibitors (MAPi) like bimagrumab. In studies, this drug helped patients lose fat while actually gaining muscle. It is currently being studied in combination with GLP-1 drugs.
Bimagrumab binds and blocks the activin type II receptor... has been shown to reduce fat mass while preserving or increasing lean mass. ... For those receiving bimagrumab, there were significant decreases in fat mass (− 20.5%) compared to placebo (− 0.5%) and increase in lean mass (+ 3.6%) compared to placebo (− 0.8%).
Why this rating
Based on a Phase 2 study (n=77) in T2D patients; results are promising but from a smaller, specific population and not yet published for obesity combinations.
Source
New drugs for the treatment of obesity: do we need approaches to preserve muscle mass?
Donna H. Ryan · Reviews in Endocrine and Metabolic Disorders · 2025
DOI 10.1007/s11154-025-09967-4
More from this paper
- GLP-1 receptor agonists (semaglutide) and dual GLP-1/GIP agonists (tirzepatide) cause significant lean mass loss during weight loss, with semaglutide losing approximately 45% of total weight as lean mass and tirzepatide losing 25.7%, posing a specific risk of frailty and fractures in older populations.Good
- Combining GLP-1 receptor agonists with other Nutrient Stimulated Hormones (NuSH) like glucagon or amylin, or using dual/triple agonists like tirzepatide, may result in less lean mass loss compared to single-agonist GLP-1 treatments.Moderate
Related findings · Macro partitioning
- Total daily protein intake of 1.6 g/kg/day is sufficient for maximizing resistance training-induced muscle gains, with an upper confidence interval of 2.2 g/kg/day.Strong
- Resistance exercise training combined with sufficient dietary protein intake acts synergistically to maximize skeletal muscle hypertrophy, with protein intake saturating around 1.6 g/kg/day for general populations and potentially requiring 2.0-2.2 g/kg/day for resistance-trained individuals.Strong
- Trans fats should be completely eliminated from the diet, as they increase LDL cholesterol, decrease HDL cholesterol, and are directly associated with increased coronary risk.Strong
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 →