Hunger is increased by the ghrelin receptor secretagogues, most strongly GHRP-6, less so GHRP-2, while ipamorelin barely affects appetite. It is suppressed by the incretins, such as semaglutide and tirzepatide, for which reduced appetite is the main effect rather than a side one. Below is where the difference comes from and what it means when choosing.
Why appetite comes into it at all
The peptides in this range act on receptors our body uses to control hunger and fullness. Growth hormone secretagogues stimulate the receptor for ghrelin, the hormone known as the hunger hormone, while incretins act on the GLP-1 receptor, which takes part in signalling fullness.
The same mechanism that gives the main effect therefore gives the effect on appetite. It is not a side effect in the everyday sense, but the other side of the same action.
Which ones increase hunger
| Molecule | Effect on appetite |
|---|---|
| GHRP-6 | The strongest hunger in the secretagogue group; starts 15 to 20 minutes after administration |
| GHRP-2 | Stimulates appetite less than GHRP-6, with the highest growth hormone peak after a single dose |
| Ipamorelin | Barely affects appetite, and does not raise cortisol or prolactin either |
These three belong to one family and differ precisely in selectivity. So choosing between them is in practice often a choice about what should happen to appetite, not about which peptide is stronger. The differences are set out in the guide to GHRP-2, GHRP-6 and ipamorelin, and the selectivity of ipamorelin itself has its own page.
Which ones suppress hunger
Incretins work the other way, and here the effect on appetite is the main effect, not a side one. Semaglutide at 2.4 mg once a week lowered body weight by about 15 per cent over roughly two years, against 2 to 3 per cent on placebo. Tirzepatide in the SURMOUNT-1 trial gave 20.9 per cent over 72 weeks, against 3.1 per cent on placebo.
Reduced appetite is one of the reasons for these figures, and with tirzepatide a second receptor, GIP, adds an effect on the fullness centres and on thermogenesis. The mechanism of the whole group is set out in the guide to GLP-1 incretins.
Reduced appetite has also been reported with melanotan 2, together with facial flushing, nausea and vomiting. It is, however, a molecule with no approval anywhere, as the guide to melanotan 2 and PT-141 explains.
What this means when choosing
| What you want | What to look for | What to avoid |
|---|---|---|
| Steady appetite with growth hormone peptides | Ipamorelin | GHRP-6 |
| Increased appetite, for example when eating is difficult | GHRP-6 | Incretins |
| Suppressed appetite | Semaglutide, tirzepatide, retatrutide | Ghrelin secretagogues |
Keep in mind that with growth hormone peptides appetite is sometimes the only noticeable signal after administration, not a measure of effectiveness. Hunger after GHRP-6 tells you the ghrelin receptor was stimulated and says nothing about how much growth hormone the pituitary released.
Prices and where to find them
| Product | Contents | Price |
|---|---|---|
| GHRP-6, Genheal | 10 mg | 20 EUR |
| GHRP-2, Genheal | 10 mg | 20 EUR |
| Ipamorelin, Bio-Peptide or Genheal | 10 mg | 40 EUR |
| Semaglutide, Bio-Peptide | 3 mg | 90 EUR |
The secretagogues are in the growth hormone peptides category, and the incretins in the weight loss peptides category. The full list of prices is on the price list.
We sell every item mentioned here as material for laboratory research and give no administration protocol with any of them. What that status means is explained in the guide to the legal status of peptides.
Frequently asked questions
Which peptide stimulates appetite the most?
GHRP-6. Hunger starts 15 to 20 minutes after administration and is the strongest in this group.
Does ipamorelin cause hunger too?
Barely. That is what its selectivity means: it does not raise cortisol or prolactin either.
Why do incretins suppress appetite?
They act on the GLP-1 receptor, which takes part in signalling fullness. With tirzepatide the GIP receptor adds an effect on the fullness centres and thermogenesis.
Does hunger after administration show that it works?
No. It shows the ghrelin receptor was stimulated, not how much growth hormone was released.
Does melanotan 2 affect appetite?
Reduced appetite has been reported, alongside facial flushing, nausea and vomiting. The molecule has no approval anywhere.
This is information about products and the state of research, not medical advice. We sell all the peptides mentioned as material for laboratory research.
Sources
- Garvey WT, Batterham RL, Bhatta M et al. Two-year effects of semaglutide in adults with overweight or obesity: the STEP 5 trial. Nature Medicine, 2022, 28(10): 2083-2091. https://doi.org/10.1038/s41591-022-02026-4
- Jastreboff AM, Aronne LJ, Ahmad NN et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1 trial). New England Journal of Medicine, 2022, 387(3): 205-216. https://doi.org/10.1056/NEJMoa2206038