Quick Answer
GLP-1 medications such as semaglutide and tirzepatide are peptides. When people compare “peptides or a GLP-1,” they’re really comparing one well-studied group of peptides with a much less-studied one. For weight loss, GLP-1 medications have far stronger evidence than the other peptides marketed for fat loss.
Who this is for: adults weighing GLP-1 medications against other peptides marketed for weight loss or body composition.
How GLP-1 Medications Work
GLP-1 (glucagon-like peptide-1) is a hormone your gut releases after eating. GLP-1 medications are designed to mimic it, and some newer ones also mimic a second gut hormone called GIP. In clinical studies, their effects have included:
- Feeling full sooner and staying full longer
- Slower stomach emptying
- More insulin released when blood sugar rises
- Less “food noise,” the frequent thoughts about eating that many people describe
Semaglutide and tirzepatide have been tested in large clinical trials involving thousands of people. In those trials, people taking them along with lifestyle changes lost, on average, a meaningful share of their body weight over about a year and a half, much more than with placebo. Brand-name versions are FDA-approved for weight management and type 2 diabetes, and some have been approved for reducing heart risks in certain people.
How Other "Weight Loss Peptides" Compare
- AOD-9604 is a fragment of growth hormone. It was developed as a weight-loss drug and tested in human trials, but it didn’t produce meaningful weight loss compared with placebo, and development stopped.
- MOTS-c appeared to improve metabolism in mice, but human research is very early.
- Growth hormone peptides such as CJC-1295 and ipamorelin are sometimes marketed for body composition. They’re designed to act through a different pathway and are not weight-loss medications.
- Retatrutide, a newer medication that acts on three hormone pathways, has shown substantial weight loss in trials so far but is still investigational and not FDA-approved.
| Comparison | GLP-1 medications | Most other popular peptides |
|---|---|---|
| FDA approval | Brand versions approved | Not approved |
| Human evidence | Large clinical trials | Mostly animal and small early studies |
| Main effect | Appetite and blood sugar | Varies by peptide |
GLP-1 medications and other peptides have very different levels of evidence.
What GLP-1 Medications Don't Do
GLP-1 medications are effective, but they’re not effortless or right for everyone. Common side effects include nausea, constipation and diarrhea, and some of the weight lost can be muscle unless people eat enough protein and strength train. Weight often returns after stopping. See GLP-1 Side Effects, How to Preserve Muscle While Losing Weight and What Happens When You Stop a GLP-1 Medication?.
Which One Makes Sense?
For medically significant weight loss, GLP-1 medications have far stronger evidence. Other peptides aren’t a replacement for a GLP-1 when weight is the main concern. The right choice depends on your health history, labs and goals, and some people shouldn’t take a GLP-1, such as those with certain thyroid cancers in their family history or a history of pancreatitis.
The clinic’s GLP-1 program uses an FDA-registered compounding pharmacy; compounded medications are not FDA-approved.
Talking With a Provider About Peptides and GLP-1s
If you’re weighing a peptide you’ve read about, Allana can review your health history, labs and goals and talk through what’s known and what isn’t, so you can make an informed decision.
Not sure whether a GLP-1 or another approach fits your goals? A consultation starts with your history and labs.
Frequently Asked Questions
Is semaglutide a peptide?
Yes. Semaglutide and tirzepatide are both peptide medications.
Can peptides be taken with a GLP-1?
Combinations add uncertainty. A provider should review any combination first.
What is retatrutide?
An investigational medication that acts on three hormone pathways. It is still in clinical trials and is not FDA-approved.
Do I need labs before starting a GLP-1?
Typically yes. A provider will usually check blood sugar, kidney function and other labs and review your history first.
References
- Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021. Read more
- Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med. 2022. Read more
- Jastreboff AM, et al. Triple-hormone-receptor agonist retatrutide for obesity. N Engl J Med. 2023. Read more
This article is for general education and is not a substitute for individual medical advice. See our medical disclaimer.
