How fast does Semaglutide work for weight loss?

Most researchers see appetite suppression within the first 1–2 weeks. Noticeable weight loss typically begins at 4–6 weeks. At therapeutic doses (1–2.5mg/week), 15–20% body weight reduction over 68 weeks was observed in clinical trials. Individual results vary significantly.

What is the difference between Semaglutide and Retatrutide?

Semaglutide is a single GLP-1 receptor agonist. Retatrutide is a triple agonist (GLP-1 + GIP + Glucagon). The glucagon receptor component significantly boosts energy expenditure on top of appetite suppression. Phase 2 trials showed Retatrutide achieving ~24% body weight loss vs ~15% for semaglutide — making it the most potent weight loss peptide studied to date. However, GI side effects can be more pronounced.

Do I need to diet while on GLP-1 peptides?

GLP-1 peptides naturally reduce appetite, making caloric restriction easier. Most researchers maintain a moderate caloric deficit and prioritize protein intake to preserve muscle mass during weight loss. Resistance training is also strongly recommended to preserve lean body mass.

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Weight Loss Peptides

Overview

Weight loss peptides have become one of the most active areas of peptide research. The GLP-1 receptor agonist class — including Semaglutide, Tirzepatide, Retatrutide, and Cagrilintide — works by mimicking gut hormones that regulate appetite, gastric emptying, and insulin secretion. Non-GLP-1 options like AOD-9604 target fat metabolism more directly. These are among the most potent fat loss tools ever studied, but require careful titration and a respect for side effects.

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Use our calculator for these peptides — presets auto-fill the math.

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Semaglutide

GLP-1 receptor agonist

Mechanism

GLP-1 receptor agonist. Slows gastric emptying, reduces appetite signaling in the hypothalamus, improves insulin sensitivity, and reduces glucagon secretion.

Benefits

✓15–20% body weight reduction (clinical trials)
✓Appetite suppression
✓Improved blood sugar control
✓Cardiovascular risk reduction

Dosing

Start 250mcg/week. Increase by 250mcg every 4 weeks based on tolerance. Typical working dose: 1,000–2,500mcg/week.

Reconstitution

5mg vial + 2mL BAC water = 2,500mcg/mL. 10mg vial + 2mL BAC = 5,000mcg/mL.

Cycle Length

Long-term. Most researchers continue until goal weight, then taper.

Timing

Once weekly SubQ injection. Rotate sites (belly, thigh, upper arm).

Stacks Well With

Cagrilintide (additive effect), AOD-9604 (different mechanism)

Cautions

GI side effects common (nausea, vomiting) especially when titrating too fast. Pancreatitis risk (rare). Avoid if personal/family history of medullary thyroid cancer.

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Retatrutide

Triple agonist (GLP-1 / GIP / Glucagon)

Mechanism

Triple receptor agonist targeting GLP-1, GIP (glucose-dependent insulinotropic polypeptide), and glucagon receptors. The glucagon component adds significant energy expenditure boost on top of appetite suppression.

Benefits

✓Up to 24% body weight reduction (phase 2 trials)
✓Strongest fat loss of any peptide class studied
✓Metabolic rate increase via glucagon action
✓Appetite suppression

Dosing

Start 500mcg/week. Titrate slowly every 4–8 weeks. Maximum studied dose: 12mg/week.

Reconstitution

6mg + 2mL BAC = 3,000mcg/mL. 10mg + 2mL BAC = 5,000mcg/mL. 12mg + 2mL BAC = 6,000mcg/mL.

Cycle Length

Long-term use. Titrate up over 3–6 months.

Timing

Once weekly SubQ.

Stacks Well With

Generally used solo given its potency. May combine with Thymalin or immune peptides.

Cautions

More aggressive GI side effects than semaglutide. Titrate conservatively. Nausea, vomiting common at higher doses.

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Tirzepatide

Dual agonist (GLP-1 / GIP), Mounjaro

Mechanism

Dual GIP/GLP-1 receptor agonist. GIP action improves the anabolic effects and reduces GI side effects compared to GLP-1 alone.

Benefits

✓20–22% body weight loss in clinical trials
✓Better GI tolerability than semaglutide alone
✓Improved insulin sensitivity

Dosing

Typical research dose 2,500mcg/week. 10mg vial + 1mL BAC = 10,000mcg/mL.

Reconstitution

10mg + 1mL BAC water = 10,000mcg/mL. Draw 25 units for 2,500mcg.

Cycle Length

Long-term.

Timing

Once weekly SubQ.

Stacks Well With

AOD-9604 for localized fat loss

Cautions

Same class cautions as semaglutide. Titrate from lower doses.

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AOD-9604

Anti-Obesity Drug, HGH fragment 176-191

Mechanism

C-terminal fragment of human growth hormone that retains the lipolytic (fat-burning) properties of HGH without stimulating IGF-1 or causing growth promotion. Directly stimulates fat breakdown and inhibits lipogenesis.

Benefits

✓Direct fat burning without HGH side effects
✓No insulin resistance
✓Can target stubborn fat areas when injected locally
✓No cancer concerns like full HGH

Dosing

300mcg/day SubQ. Best results on an empty stomach in the morning.

Reconstitution

5mg + 3mL BAC = 1,667mcg/mL. 6mg + 4mL BAC = 1,500mcg/mL.

Cycle Length

8–12 weeks on, 4 weeks off.

Timing

Morning on empty stomach. Can inject near stubborn fat areas.

Stacks Well With

GLP-1 peptides (different mechanism), Tesamorelin

Cautions

Well tolerated. No major safety concerns identified.

Calculate AOD-9604 dose →

Weight Loss Peptides

Overview

Calculate Your Dose

Semaglutide

Mechanism

Benefits

Dosing

Reconstitution

Cycle Length

Timing

Stacks Well With

Cautions

Retatrutide

Mechanism

Benefits

Dosing

Reconstitution

Cycle Length

Timing

Stacks Well With

Cautions

Tirzepatide

Mechanism

Benefits

Dosing

Reconstitution

Cycle Length

Timing

Stacks Well With

Cautions

AOD-9604

Mechanism

Benefits

Dosing

Reconstitution

Cycle Length

Timing

Stacks Well With

Cautions

Frequently Asked Questions