The muscle growth from this drug wasn’t because belly fat went down—it was more likely due to a rise in a growth-related hormone called IGF-1.
Scientific Claim
In HIV-positive adults with abdominal obesity who responded to tesamorelin with ≥8% VAT reduction, changes in muscle area were not explained by changes in visceral adipose tissue but were partially explained by changes in insulin-like growth factor-1 (IGF-1), suggesting IGF-1 mediates muscle growth effects.
Original Statement
“In contrast, changes in total and lean muscle density with tesamorelin were attenuated across most of the muscle groups after adjusting for VAT. In contrast to the muscle density findings, muscle area and lean muscle area were independent of VAT but not IGF-1 changes.”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
probability
Can suggest probability/likelihood
Assessment Explanation
The study uses regression adjustments to infer mediation, but IGF-1 was not directly manipulated. The language 'partially explained' reflects probabilistic inference, not definitive causation.
More Accurate Statement
“In HIV-positive adults with abdominal obesity who responded to tesamorelin with ≥8% VAT reduction, changes in muscle area were not explained by changes in visceral adipose tissue but were partially associated with changes in insulin-like growth factor-1 (IGF-1), suggesting IGF-1 may mediate muscle growth effects.”
Evidence from Studies
Supporting (0)
Contradicting (1)
The Growth Hormone Releasing Hormone Analogue, Tesamorelin, Decreases Muscle Fat and Increases Muscle Area in Adults with HIV
The study shows that the drug makes muscles bigger and stronger in people with HIV and belly fat, but it never measured or mentioned IGF-1, so we can't say if IGF-1 is the reason why muscles grew.