In older male mice, a treatment that increases muscle size did not raise total energy use, even though similar genetic changes in other mice did raise energy use, showing that muscle growth alone does not always change how much energy the body burns.
See the scientific wording
In old male mice, a 4-week anti-myostatin antibody treatment resulted in increased muscle mass without a corresponding increase in whole-body energy expenditure, differing from the metabolic effects observed in myostatin-knockout mice and indicating that modest muscle hypertrophy alone may not alter metabolic rate.
Correlational — new studies may shift this
Randomized trialsOne low-scoring study links this claim to the outcome, but causation is not established.
What the research says
1 study reviewedSupporting (1)
Cohort StudyAnimal2016
In older male mice, giving a drug to make muscles bigger didn’t make them burn more calories, even though bigger muscles usually do. This suggests that just a little bit of extra muscle doesn’t change how much energy the whole body uses.
Contradicting (0)
No contradicting studies found yet
That doesn't mean it's settled — it just means no study has tested the opposite.
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Blocking myostatin makes muscles bigger, but the extra muscle doesn't burn more energy at rest because each gram of muscle uses the same amount of energy as before. The body doesn't increase its overall calorie burning just because there's more muscle, even though the muscles get stronger and handle sugar better.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting study
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In older male mice, a treatment that increases muscle size did not raise total energy use, even though similar genetic changes in other mice did raise energy use, showing that muscle growth alone does not always change how much energy the body burns.
Mechanism
1 studyMaking muscles bigger by blocking myostatin doesn't make the body burn more calories at rest because each gram of muscle still uses the same amount of energy. The muscles get stronger and handle sugar better, but the total energy use stays the same because the muscle cells don't become more metabolically active.
Blocking myostatin makes muscles bigger, but the extra muscle doesn't burn more energy at rest because each gram of muscle uses the same amount of energy as before. The body doesn't increase its overall calorie burning just because there's more muscle, even though the muscles get stronger and handle sugar better.
Myostatin binds to activin type II receptors on muscle cells, suppressing signals that promote protein synthesis and muscle growth
Inhibition of myostatin prevents receptor activation, leading to reduced Smad2/3 phosphorylation and removal of suppression on muscle protein synthesis pathways
Muscle protein synthesis increases, resulting in myofiber hypertrophy and increased lean body mass
Increased muscle mass enhances insulin-stimulated glucose uptake in muscle tissue, improving whole-body glucose disposal
Basal metabolic rate per gram of muscle remains unchanged, so total energy expenditure does not increase despite greater muscle mass
Evidence from Studies
Supporting (1)
Community contributions welcome
Anti-myostatin antibody increases muscle mass and strength and improves insulin sensitivity in old mice
In older male mice, giving a drug to make muscles bigger didn’t make them burn more calories, even though bigger muscles usually do. This suggests that just a little bit of extra muscle doesn’t change how much energy the whole body uses.
Contradicting (0)
Community contributions welcome
Score Breakdown
No multi-axis breakdown available yet. The overall Pro / Against score above is the best signal.
- No clinical evidence is available; the score reflects mechanistic plausibility only.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
Systematic Review of Anti-Myostatin Antibody Effects on Energy Expenditure and Muscle Mass in Aged Mice
Population: Aged male mice; Intervention: Anti-myostatin antibody treatment; Comparator: Placebo or control antibody; Outcome: Whole-body energy expenditure and muscle mass; Duration: 4 weeks or longer; Inclusion: All published controlled studies with standardized metabolic measurements.
Double-Blind Randomized Trial of Anti-Myostatin Antibody vs. Placebo on Energy Expenditure in Aged Male Mice
Population: Aged male mice; Intervention: Anti-myostatin antibody; Comparator: Isotype control antibody; Outcome: Whole-body energy expenditure (via indirect calorimetry) and muscle mass (via wet weight or DEXA); Duration: 4 weeks; Design: Randomized, blinded, with pre- and post-treatment measurements.
Longitudinal Cohort of Aged Male Mice Treated with Anti-Myostatin Antibody: Muscle Mass and Energy Expenditure Trajectories
Population: Aged male mice; Intervention: Anti-myostatin antibody administered at baseline; Comparator: No treatment or vehicle control; Outcome: Serial measurements of muscle mass and energy expenditure at weekly intervals over 4 weeks; Design: Prospective, non-randomized, observational cohort.
Comparison of Metabolic Effects in Aged Male Mice Treated with Anti-Myostatin Antibody vs. Myostatin-Knockout Mice
Population: Aged male mice; Intervention: Anti-myostatin antibody treatment; Comparator: Myostatin-knockout mice of same age; Outcome: Whole-body energy expenditure, muscle mass, and metabolic gene expression; Duration: 4 weeks; Design: Parallel groups with identical housing and measurement protocols.
In Vitro Analysis of Muscle Cell Metabolic Activity Following Myostatin Inhibition in Aged Mouse Myotubes
Population: Primary myotubes derived from aged male mice; Intervention: Anti-myostatin antibody or siRNA against myostatin; Comparator: Control siRNA or IgG; Outcome: Oxygen consumption rate (OCR), glucose uptake, and mitochondrial function; Duration: 72 hours; Design: Controlled cell culture with standardized media and stimulation.