The drug makes the fat around the organs healthier-looking on scans more than the fat under the skin — it works better on belly fat than on thigh or arm fat.

Even when scientists account for how much belly fat was lost, the fat that’s left still gets denser and healthier-looking on scans — meaning the drug is doing something beyond just shrinking fat.

Before starting the drug, the fat quality in the group that got the drug was just like the group that got the placebo — so any differences later were due to the treatment.

For HIV patients with excess belly fat who responded to the drug tesamorelin, taking the drug for 26 weeks made the fat around their organs denser by 2.3 points on a CT scan scale, even after accounting for changes in fat amount, which suggests the fat became healthier.

The fat under the skin gets denser and healthier-looking on scans even when the amount of that fat doesn’t change much — the drug is improving its quality directly.

Before treatment, the fat under the skin looked just as healthy on scans in both the drug and placebo groups — so any changes later were caused by the drug.