Do all peptides work? Evidence and FDA approval

This content is sourced exclusively from TruthTides clinical reference data and does not constitute medical advice.

Is every peptide a proven winner?

If you spend enough time on the internet, you might think peptides are all equal. It sounds like a dream: whether you want to lose weight or boost your immune system, there is a tiny protein chain ready to save the day. Look, I know this sounds weird, but not all peptides are created equal. In fact, some things people call peptides technically are not peptides at all.

Take MK-677, for example. People talk about it in the same breath as other therapies, but it is actually a small-molecule chemical that mimics a hormone called ghrelin. It is not even a peptide in the strict scientific sense. While it was shown in a two-year study to restore certain growth markers and add about 1.1kg of fat-free mass, it is not FDA-approved and actually raised fasting glucose levels in users. Not exactly the "perfect" track record the hype might suggest.

Why do some have an A+ while others are just 'meh'?

When we look at evidence, we see a massive split. You have the heavy hitters like Semaglutide and Tirzepatide, which have Grade: A+ ratings. These are FDA-approved and have massive trials behind them.

• Semaglutide showed a 14.9% weight loss in its STEP 1 trial.
• Tirzepatide went even further with a 22.5% weight loss in the SURMOUNT-1 study.

But even these "proven" options have fine print. For Semaglutide, nausea is a very real thing for about 44% of people, and there are strong signals for more serious issues like delayed gastric emptying and pancreatitis. Scientists are also keeping an eye on how much muscle people lose alongside the fat.

The 'Approved Over There' problem

Then there is the category of things that work elsewhere but have a giant question mark over them in the United States. Thymosin Alpha-1 is approved in over 35 countries to help with things like hepatitis and vaccine responses. It even has data from over 1,000 patients. But in the US? It is not FDA-approved.

Similarly, Semax has been a standard treatment for strokes in Russia for over 25 years. It helps the brain by upping something called BDNF. However, there is very little Western validation or large-scale clinical trials. It is a classic case of "we think it works, but the local rulebook says we need more proof."

What happens when you stop?

Even when a peptide is "proven" to do something, it might not be a permanent fix. Tesamorelin is Grade: A and FDA-approved for reducing deep belly fat in patients with HIV. It works, cutting that specific fat by about 18%. But here is the catch: those effects completely reverse once you stop using it.

Scientists are still working on this one—turns out the human body is complicated. Who knew? Whether it is the substantial weight regain seen after stopping Semaglutide or the lack of long-term cardiovascular data for Tirzepatide, "proven" does not mean "perfect."

This is a great one to bring up with your doctor. You can find peptide-experienced physicians in our Find a Doctor directory.