Peptides for weight loss — a plain English guide

Which research peptides are studied for fat loss, how they work, and how they compare to approved GLP-1 medicines — explained in plain English.

Several research peptides are studied specifically for weight loss and metabolic health. The GLP-1 class compounds (semaglutide, tirzepatide, retatrutide) are the most researched and show the strongest data. AOD 9604 offers a different mechanism — direct fat cell stimulation without the hunger regulation pathway.

The compounds studied for weight loss

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Retatrutide

Triple GLP-1/GIP/glucagon receptor agonist — next-generation metabolic research compound

Significant body weight reduction in clinical trials

Improved blood glucose and insulin sensitivity

Reduced appetite via central GLP-1 mechanisms

Full research guide →

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Semaglutide

GLP-1 receptor agonist approved for type 2 diabetes and obesity management

Sustained weight reduction in obese and overweight individuals

Improved glycaemic control in type 2 diabetes

Reduced appetite and caloric intake

Full research guide →

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Tirzepatide

Dual GLP-1/GIP receptor agonist approved for diabetes and obesity

Greater weight reduction than semaglutide in head-to-head trials

Improved HbA1c reduction in type 2 diabetes

Reduced appetite via dual GIP/GLP-1 mechanism

Full research guide →

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AOD 9604

Modified GH fragment studied for fat metabolism without the growth-promoting effects of full GH

Stimulates fat breakdown via beta-3 adrenergic pathway

No IGF-1 elevation — does not promote tissue growth

GRAS status from FDA for food ingredient use

Full research guide →

How GLP-1 peptides work

GLP-1 (glucagon-like peptide 1) is a hormone naturally produced in your gut after eating. It signals to your brain that you are full, slows stomach emptying, and improves insulin response. GLP-1 receptor agonists mimic this effect — but for longer and more powerfully than the natural hormone.

How AOD 9604 is different

AOD 9604 is a fragment of human growth hormone (amino acids 176-191) developed at Monash University in Australia. Unlike GLP-1 compounds, it does not affect appetite. Instead it works directly on fat cells via beta-3 adrenergic receptors — stimulating lipolysis (fat breakdown) without the growth-promoting effects of full growth hormone.

What the research shows

Which to research first?

If you are researching GLP-1 compounds, retatrutide represents the highest-opportunity compound — it has the strongest Phase 2 data, is unscheduled across most markets (no prescription needed for research), and has near-zero competition in search results as of 2025.