Fat loss

"you lose muscle on these drugs"

Partly true, and it is not special to the drugs. In the tirzepatide body-scan substudy, about a quarter of the weight lost was lean mass, the same share as placebo. A 2026 review looked at 20 trials in 15,782 people. It asked how much of the lost weight was lean mass. For semaglutide it was about 35%. For tirzepatide, about 25%. For lifestyle changes alone, about 26%. One caution: "lean mass" on a scan includes organs and water, not just muscle.

"it all comes back when you stop"

True, in both big trials. One part of the semaglutide trial followed people after they stopped. That group had lost 17.3% of their weight over 68 weeks. In the next year, about two thirds of it came back. They ended about 5.6% below where they started. In the tirzepatide withdrawal trial, people who switched to placebo regained 14% over 52 weeks, while those who stayed on lost a further 5.5%.

"lift and eat protein and you keep your muscle"

Supported, and it reduces the loss rather than stopping it. A review of 114 trials in 4,184 people found lean mass was held when resistance training was added to eating less. Higher protein kept about 0.43 kg more. A 2026 trial followed 120 people on tirzepatide. Those who lifted weights lost 3.57 kg of lean mass. Those who did not lift lost 4.67 kg. The lifters got stronger. The others got weaker.

"compounded or research-grade is the same drug"

No. The FDA says these are not approved or checked for safety, quality or strength. Some use a different form of the ingredient, such as semaglutide sodium or acetate, which is not the same active ingredient. Dosing mistakes have put people in hospital. As of May 31, 2026 the FDA had 990 adverse event reports for compounded semaglutide and over 730 for compounded tirzepatide, and also warns about counterfeit product.

"microdosing gives the benefit without the side effects"

No trial found. We found no published trial of below-label doses for weight loss. One study looked at the records of people who stayed on the lowest approved dose. After 12 months, weight had changed by about 2.2% on semaglutide and 5.5% on tirzepatide. Side effects were still recorded.