Because so few people finished the study and the muscle energy didn’t improve much more in the drug group than the placebo group, we can’t say for sure the drug caused the improvement.

We know muscle energy recovery got better, but we don’t know if it’s because there are more mitochondria, bigger ones, or just ones that work better.

Before starting the study, both the drug group and the placebo group had the same muscle energy recovery ability, so any later differences weren’t due to starting out differently.

In a 12-month randomized, double-blind, placebo-controlled trial, tesamorelin improved mitochondrial oxidative capacity in obese adults with reduced growth hormone secretion, as measured by enhanced phosphocreatine recovery after exercise, with improvements strongly associated with increased IGF-I levels.

The muscle energy improvement wasn’t because people lost weight or got more active — it seemed to be linked directly to IGF-I levels instead.

When obese people with low growth hormone took a drug called tesamorelin for a year, their muscle energy recovery got better, which means their muscle cells may have become better at making energy.