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Peptides/Weight and appetite

Tirzepatide

Also sold as Mounjaro, Zepbound

The strongest weight loss medicine currently approved. It works on two gut hormones instead of one, and trial results reached about 20%.

Approved medicineStrong human evidence
CC0 1.0 · source

At a glance

What people use it for

  • Losing a large amount of weight
  • Managing type 2 diabetes
  • Obstructive sleep apnoea in people with obesity

How it is taken

A once-weekly injection using a pre-filled pen, starting at a low dose and increasing every four weeks.

Evidence

Strong human evidence

Good to know

  • Nausea, diarrhoea and constipation, worst in the first weeks and after dose increases
  • Muscle loss without enough protein and resistance training
  • Gallbladder problems and, rarely, pancreatitis
  • Weight regain after stopping, as with any appetite medicine

Tirzepatide does what semaglutide does, and then a bit more. It mimics two gut hormones rather than one: GLP-1, which reduces appetite, and GIP, which appears to improve how the body handles fat and sugar. In head-to-head results it produces more weight loss than any other approved medicine.

What people take it for

The same reasons as semaglutide, usually after semaglutide has either stopped working well enough or was never quite enough to begin with. Appetite drops, meals get smaller without much effort, and the mental noise around food fades.

It is also approved for type 2 diabetes, and more recently for sleep apnoea in people carrying significant excess weight, which is a genuinely meaningful quality-of-life change for anyone who has been sleeping badly for years.

What the evidence shows

In the SURMOUNT-1 trial, adults without diabetes lost about 20% of their body weight on the highest dose over 72 weeks. In SURPASS-2, it beat semaglutide directly on both blood sugar and weight. These are large randomised trials, not observational data.

That 20% figure is worth sitting with. It is close to the territory previously reserved for bariatric surgery.

What to know before

Everything true of semaglutide is true here, sometimes more so. The digestive side effects are real, they are worst early, and the slow dose schedule exists to manage them.

Supply has been intermittent, which has pushed people toward compounded versions and unregulated sellers. That is where the actual danger in this category lives, and it is a supply problem rather than a drug problem.

Last reviewed .