Retatrutide

How it works

It activates three hormone receptors at once: GLP-1 and GIP, which cut appetite and improve insulin, and glucagon, which raises energy use and fat burning in the liver.

What it is used for

Obesity. Also studied for type 2 diabetes, fatty liver and knee osteoarthritis.

What the evidence says

In a phase 2 trial, the highest dose led to about 24% weight loss in 48 weeks. Phase 3 trials are running and it is not approved yet.

Side effects and cautions

Nausea, vomiting, diarrhea and constipation, more at higher doses, plus a higher heart rate. Anything sold outside clinical trials is unregulated.

Half-life

About 6 days (clinical studies)

Makes sense for

• Adults with obesity, mainly within clinical trials

Does not make sense for

• A history of pancreatitis or gallbladder disease
• Medullary thyroid cancer or MEN2
• People at a healthy weight

Boost the effect

• High-protein meals (about 1.2–1.6 g per kg of body weight a day): help keep muscle while you lose weight
• Strength training 2–3 times a week: protects muscle and strength
• Plenty of water and fiber: ease the usual constipation and nausea