-----|-------------------------| | Total weight loss | 22.1% | | Fat mass loss | 38.2% | | Lean mass loss | 3.6% | | Percent from fat | 92.8% |
Read that again: 92.8% of weight lost came from fat.
Compare to typical GLP-1 results: 60-70% fat, 30-40% lean mass.
This isn't incremental improvement. It's a categorical change in what weight loss medication can achieve.
Why This Matters for Men
Muscle loss has been the Achilles heel of GLP-1 therapy for men who lift or care about body composition.
The fear: "Sure, I'll lose 50 lbs, but I'll also lose all my muscle and end up skinny-fat."
BELIEVE proves this isn't biologically necessary. The muscle loss is addressable. With the right intervention, you can lose weight that is almost entirely fat.
For men, this means: - Strength preservation possible - Body composition can actually improve (not just get smaller) - Metabolic benefits of muscle maintained - The "wasting away" concern is solvable
How Bimagrumab Works
Bimagrumab is a monoclonal antibody that blocks activin type II receptors (ActRII).
These receptors, when activated by myostatin and related proteins, inhibit muscle growth and promote muscle breakdown.
By blocking these receptors, bimagrumab: - Prevents muscle catabolism - May actually increase muscle mass - Allows fat loss to proceed while muscle is protected
Think of it as removing the brakes on muscle preservation.
The Combination Effect
Neither drug alone achieves what the combination does:
Semaglutide alone: - ~15-17% weight loss - 30-40% from lean mass - Good fat loss, but muscle sacrifice
Bimagrumab alone: - Modest effects on body composition - Not primarily a weight loss drug - Some muscle gain, modest fat loss
Semaglutide + Bimagrumab: - 22.1% weight loss (superior) - 92.8% from fat (dramatic improvement) - Fat loss with muscle preservation
The combination is synergistic — greater than the sum of parts.
When Will Bimagrumab Be Available?
Current status: Not FDA-approved. Still in clinical development.
Timeline: Unclear. Phase 3 trials needed. Optimistically 2027-2028.
Eli Lilly: Has acquired bimagrumab rights and is likely developing combinations with their GLP-1s (tirzepatide).
Bottom line: This isn't available yet. But it proves the concept and signals where the field is heading.
What You Can Do Now
While waiting for bimagrumab or similar drugs:
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Resistance training: The most accessible muscle preservation tool. 2-3x weekly, compound movements.
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High protein intake: 1.2-1.6 g/kg body weight daily. The body needs building blocks to preserve muscle.
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Avoid extreme deficits: Severe caloric restriction accelerates muscle loss. Let the GLP-1 create a moderate deficit.
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Creatine: 5g daily. Supports muscle function and may help preservation.
These interventions won't achieve BELIEVE-level preservation. But they can reduce lean mass loss from 35% to 20-25% — a meaningful improvement.
Implications for GLP-1 Prescribing
BELIEVE may change how we think about GLP-1 therapy:
Current approach: - Prescribe GLP-1, hope for the best on muscle - Maybe mention "eat protein and exercise" - Accept significant lean mass loss
Future approach: - GLP-1 + muscle-preserving agent as standard combination - Proactive body composition monitoring - True body recomposition, not just weight loss
The distinction between "losing weight" and "losing fat while preserving muscle" is enormous. BELIEVE shows the latter is achievable.
Other Muscle-Preserving Agents in Development
Bimagrumab isn't the only option being studied:
HCG + GLP-1: Some clinics use HCG to support testosterone/muscle during weight loss. Limited data.
Testosterone + GLP-1: TRT provides anabolic support. But comes with TRT trade-offs (fertility, dependency).
SARMs: Selective androgen receptor modulators. Not FDA-approved, legal gray area, unknown long-term safety.
Future drugs: Multiple companies are developing muscle-preserving agents for combination with GLP-1s.
The recognition that body composition matters — not just scale weight — is driving pharmaceutical development.
The Bigger Picture
BELIEVE represents a paradigm shift:
Old paradigm: Weight loss is weight loss. Lose pounds, improve health.
New paradigm: Body composition matters. Losing fat while preserving muscle is fundamentally different from losing weight indiscriminately.
For men, this shift is validating. The concern about muscle loss wasn't irrational — it was anticipating a real problem that the field is now addressing.
The medications are catching up to what men have always understood: you don't just want to be smaller, you want to be lean and strong.
The Bottom Line
BELIEVE proved that 92.8% of weight loss can come from fat when GLP-1s are combined with muscle-preserving medication.
This isn't available today. But it: - Validates concerns about muscle loss - Proves the problem is solvable - Signals where treatment is heading - Gives reason to use current muscle-preservation strategies
The future of GLP-1 therapy for men looks like true body recomposition — fat loss with muscle preservation. BELIEVE is the first clinical proof it's possible.
Related Articles: - How to Minimize Muscle Loss on GLP-1s: The Protocol - What Bodybuilders Are Saying About GLP-1s - GLP-1 Medications for Men: The Complete 2026 Guide
Last updated: January 2026
Sources: BELIEVE trial results, presented at ObesityWeek 2024
Medical disclaimer: This content is for informational purposes only. Bimagrumab is not FDA-approved.