Peptide injections for weight loss, compared and dosed

Among peptide injections for weight loss, the GLP-1 family has the biggest trial results. In phase 3, retatrutide 12 mg took off an average 25.0% of body weight over 80 weeks. Tirzepatide 15 mg took off 20.9% over 72 weeks, and semaglutide 7.2 mg took off 18.7% over 72 weeks. Tesamorelin, MOTS-c and 5-Amino-1MQ work on fat in other ways.

How weight-loss injections work

• Hormone-receptor agonists. GLP-1 is a hormone that regulates appetite and calorie intake. Semaglutide and liraglutide act on its receptor. Tirzepatide adds the GIP receptor. Retatrutide adds the glucagon receptor too. Survodutide pairs glucagon with GLP-1.
• Amylin analogs. Cagrilintide is a long-acting analog of amylin, a hormone from the pancreas that brings on fullness. Its pairing with semaglutide goes by CagriSema.
• GH-axis peptides. Tesamorelin is a GHRH analog. It makes the pituitary release its own growth hormone in pulses, and growth hormone breaks down fat.
• GH fragment. HGH Fragment 176-191 is residues 176 to 191 of growth hormone, a 16-amino-acid piece.
• Cell-energy compounds. MOTS-c is a 16-amino-acid peptide coded in mitochondrial DNA. It switches on AMPK, mainly in muscle. 5-Amino-1MQ is a small molecule, not a peptide. It blocks the enzyme NNMT (nicotinamide N-methyltransferase). In fat cells, NNMT blockers raised NAD+ and cut fat-making.

Trial results side by side

Each row in the table comes from its own trial, and the trials ran for different lengths. One trial put two of these head to head. SURMOUNT-5 was open-label, and people ran the top dose they tolerated. That meant 10 or 15 mg of tirzepatide, or 1.7 or 2.4 mg of semaglutide. Tirzepatide took off 20.2% against 13.7% on semaglutide over 72 weeks, and 18.4 cm of waist against 13.0 cm.

Semaglutide and tirzepatide

• Semaglutide (Wegovy) dosing. It is injected once a week. The label starts at 0.25 mg for 4 weeks, then steps through 0.5, 1 and 1.7 mg, 4 weeks each, to 2.4 mg. Once 2.4 mg has gone well for at least 4 weeks, the label allows up to 7.2 mg. Its Half-life is about a week.
• Semaglutide results. In STEP 1, the 2.4 mg dose took off 14.9% over 68 weeks, and 50.5% of people lost at least 15%. In STEP UP, 7.2 mg took off 18.7% over 72 weeks, against 15.6% on 2.4 mg.
• Tirzepatide (Zepbound) dosing. It is injected once a week. The label starts at 2.5 mg for 4 weeks, then 5 mg, and adds 2.5 mg after at least 4 weeks on a dose. Maintenance is 5, 10 or 15 mg, and 15 mg is the top. Its half-life is about 5 days.
• Tirzepatide results. In SURMOUNT-1, 15 mg took off 20.9% over 72 weeks, and 57% of people on it lost at least 20%. The label says it takes off more fat than lean mass and cuts calorie intake, likely through appetite.

Retatrutide, the triple agonist

• What it adds. Retatrutide acts on the GLP-1, GIP and glucagon receptors. In obese mice, the glucagon receptor added energy burn to the drop in eating that GLP-1 and GIP drive.
• Phase 2. Over 48 weeks, 12 mg took off 24.2%. On that dose, 100% of people lost at least 5% and 83% lost at least 15%.
• Phase 3. TRIUMPH-1 came out on September 29, 2026. Over 80 weeks, 4, 9 and 12 mg took off 17.6%, 23.7% and 25.0%, against 3.9% on placebo. In adults with type 2 diabetes (TRIUMPH-2), the same doses took off 11.9%, 16.8% and 18.8%, against 5.1% on placebo.
• Dosing. In phase 3, the dose climbed on a fixed schedule over 16 weeks to 4, 9 or 12 mg once a week. It then held there for 64 weeks. The phase 2 trial ran dose groups from 1 to 12 mg. The Retatrutide page has the step-by-step ladder people run.

CagriSema, survodutide and liraglutide

• CagriSema. It pairs cagrilintide 2.4 mg with semaglutide 2.4 mg, once a week. In REDEFINE 1 the pair took off 20.4% over 68 weeks, against 3.0% on placebo.
• Cagrilintide on its own. Weekly doses of 0.3 to 4.5 mg took off 6.0% to 10.8% over 26 weeks. The top dose beat liraglutide 3.0 mg, 10.8% against 9.0%.
• How the pair is timed. Cagrilintide's half-life runs 159 to 195 hours and semaglutide's 145 to 165 hours, so both suit one shot a week. In the phase 1b trial the two were raised together every 4 weeks over 16 weeks.
• Survodutide. It acts on the glucagon and GLP-1 receptors and is dosed once a week. In SYNCHRONIZE-1, doses raised up to 3.6 mg or 6.0 mg took off 12.2% and 13.0% over 76 weeks, against 5.4% on placebo.
• Liraglutide (Saxenda). It is the daily one in this group. The label starts at 0.6 mg a day and raises it each week to 3 mg. Its half-life is about 13 hours, which suits once-a-day dosing. In SCALE, 3.0 mg took off 8.4 kg over 56 weeks, against 2.8 kg on placebo.

Tesamorelin for visceral fat

Both tesamorelin trials enrolled adults with HIV and extra belly fat. They measured visceral fat, the deep belly fat packed around the organs.

• The result. In a 26-week trial, 2 mg a day cut visceral fat by 15.2%, while it rose 5.0% on placebo. IGF-1 rose 81.0%.
• Longer runs. A second trial found a 10.9% drop at 6 months, and about 18% in people who stayed on it to 12 months.
• Weight holds steady. Belly fat under the skin and limb fat did not change, and the label calls tesamorelin weight neutral.
• Dosing. The trials gave 2 mg once a day under the skin. The current labels give 1.4 mg (Egrifta SV) or 1.28 mg (Egrifta WR) once a day. The labels say both give about the same blood levels as the original 2 mg dose. The Tesamorelin page covers bedtime timing and cycles.
• After stopping. In the second trial, visceral fat came back quickly once people switched to placebo.

MOTS-c and 5-Amino-1MQ

• MOTS-c in mice. On a high-fat diet, mice given MOTS-c stayed lean and kept their insulin sensitivity. Older mice given it kept their insulin sensitivity too. In a 2021 study it raised physical performance in young, middle-aged and old mice.
• Exercise link. Exercise raises the body's own MOTS-c in muscle and blood.
• MOTS-c in people. A phase 2a trial in adults with prediabetes and overweight or obesity began in February 2026. It compares a daily shot under the skin with placebo over 12 weeks, and its main measure is insulin sensitivity.
• How people run MOTS-c. The common range is 500 to 1,000 mcg once a day, often starting at 250 to 500 mcg. Cycles run 8 to 12 weeks, then 4 to 6 weeks off. The MOTS-c page has the full protocol.
• Why NNMT. In mice on a high-fat diet, knocking down NNMT in fat and liver raised energy use and kept them leaner.
• 5-Amino-1MQ in mice. In obese mice, 11 days of injections took off about 5.1% of body weight. Control mice given saline shots gained about 1.4%. A main fat pad shrank about 35%, fat cells shrank by more than 30%, and food intake did not change.
• How people run 5-Amino-1MQ. Most people run 5 mg once a day, within a range of 2.5 to 10 mg, and use 2.5 mg as a first-week check. Blocks run 4 to 6 weeks, then at least 4 weeks off. The 5-Amino-1MQ page has the full protocol.

HGH Fragment 176-191

People run HGH Fragment 176-191 at 250 to 500 mcg once a day on an empty stomach, starting at 250 mcg. Cycles run 8 to 12 weeks, then 4 weeks off. The HGH Fragment 176-191 page has the full protocol.

How people dose them

The reconstitution calculator turns any of these doses into units on the syringe for your vial size.

What to watch for

• What people notice. Gut effects are the most common, led by nausea and diarrhea. Most are mild to moderate and show up mainly during the dose climb.
• Higher doses, more gut effects. In TRIUMPH-2, 14%, 21% and 28% of people had nausea on retatrutide 4, 9 and 12 mg, against 8% on placebo. In STEP UP, 70.8% had gut effects on semaglutide 7.2 mg and 61.2% on 2.4 mg, against 42.8% on placebo.
• Skin sensitivity. An odd skin sensation called dysesthesia shows up at higher doses. In STEP UP, 22.9% reported it on semaglutide 7.2 mg, against 6.0% on 2.4 mg and 0.5% on placebo. In TRIUMPH-2 the rates were 4%, 6% and 7% on retatrutide 4, 9 and 12 mg, against 1% on placebo.
• Heart rate. In retatrutide's phase 2 trial, heart rate rose with the dose. The rise peaked at 24 weeks, then came down.
• How people handle it. They climb more slowly. The Wegovy label says to hold a step for another 4 weeks if it isn't tolerated. In retatrutide's phase 2 trial, starting at 2 mg instead of 4 mg eased gut effects in part.
• Muscle. In a SURMOUNT-1 body-scan study, about three quarters of the weight lost on tirzepatide was fat and a quarter was lean mass. Placebo showed the same split.
• Stopping. A year after stopping semaglutide and the trial's lifestyle program, people had regained two thirds of the weight they lost. In SURMOUNT-4, people who switched from tirzepatide to placebo saw their weight rise 14.0% over the next 52 weeks. Those who stayed on lost another 5.5%.
• Skip it or take care if. The Wegovy and Zepbound labels carry a boxed warning on thyroid C-cell tumors seen in rodents. Both rule out people with a personal or family history of medullary thyroid cancer, or with MEN 2 (multiple endocrine neoplasia type 2). The Wegovy label also lists pancreatitis and gallbladder disease. The Wegovy, Zepbound and Saxenda labels advise against running two GLP-1 drugs together.

Common questions

What is the strongest peptide injection for weight loss? Of the compounds here, retatrutide has the biggest result, 25.0% over 80 weeks on 12 mg in phase 3. Head to head, tirzepatide beat semaglutide, 20.2% against 13.7% over 72 weeks.

Which peptides have been studied for belly fat? Tesamorelin is the one studied for visceral fat, the fat around the organs. In adults with HIV and extra belly fat, it cut that fat 15.2% in 26 weeks while placebo rose 5.0%. Tirzepatide also cut visceral fat on MRI scans in adults with type 2 diabetes, against insulin degludec. In SURMOUNT-5 it took 18.4 cm off the waist.

How do GLP-1, GIP and glucagon agonists differ from MOTS-c? The agonists act on hormone receptors. GLP-1 and GIP cut calorie intake. In obese mice, glucagon added energy burn on top of that. MOTS-c is a peptide coded in the mitochondria that switches on AMPK, mainly in muscle.

Is 5-Amino-1MQ a peptide? No. It is a small molecule, 5-amino-1-methylquinolinium, with a molecular weight of about 159. It blocks the enzyme NNMT.

How fast does the weight come off? In retatrutide's phase 2 trial, 12 mg took off 17.5% by week 24 and 24.2% by week 48. Semaglutide and tirzepatide climb for months first. Semaglutide reaches 2.4 mg in week 17, and SURMOUNT-1 took 20 weeks to climb to the top tirzepatide doses.

What happens when you stop? Most of the weight comes back. A year after stopping semaglutide, people had regained two thirds of what they lost. After switching off tirzepatide, people's weight rose 14.0% over 52 weeks.

Can you stack them? The studied pairing is cagrilintide with semaglutide, 2.4 mg of each once a week. The Wegovy, Zepbound and Saxenda labels advise against two GLP-1 drugs together. The library's Retatrutide + 5-Amino-1MQ protocol pairs the two, since 5-Amino-1MQ works on a different target.