Weight-Loss Injections in Bangkok: What Mounjaro and Ozempic Do to Your Body Shape

Mounjaro and Ozempic are prescription medicines that act on gut hormones, reduce appetite and help you feel full for longer. They lower your body weight as a whole: they cannot choose the belly over the hips, and fast weight loss can leave skin looking looser. If you want to change the shape of particular areas, that is a different question from losing weight. (Sources: NHS: tirzepatide (opens in a new tab); NHS: semaglutide (opens in a new tab); Cleveland Clinic (opens in a new tab))

What weight-loss injections are

Mounjaro and Ozempic are brand names, and they contain two different active ingredients. (Sources: NHS: tirzepatide (opens in a new tab); NHS: semaglutide (opens in a new tab))

• Mounjaro contains tirzepatide. The NHS (opens in a new tab) describes it as a medicine used to manage type 2 diabetes or obesity, which activates the gut hormone receptors GLP-1 and GIP. In the US, tirzepatide for weight management is sold under a different name: the FDA approved Zepbound (opens in a new tab) in November 2023, for use alongside a reduced-calorie diet and increased physical activity.
• Ozempic contains semaglutide. According to the NHS (opens in a new tab), Ozempic is used to manage type 2 diabetes, while semaglutide for obesity is sold as Wegovy.

Both are only available with a prescription. Both work, in the words of the NHS, by reducing your appetite and helping you to feel fuller for longer. Common side effects listed by the NHS include feeling sick, being sick, constipation, diarrhoea, tiredness and hair loss. Whether one of them is right for you is a decision for your doctor.

Weight goes down everywhere, not in one area

Because these medicines work through appetite, they change how much you eat, not where your body takes the fat from. A body-composition analysis from the STEP 1 trial (opens in a new tab) of semaglutide measured the whole body by DEXA scan: total fat mass went down by 19.3% and visceral (internal) fat by 27.4%. Total lean body mass, which includes muscle, went down too, by 9.7%.

Two things follow from that. You cannot decide in advance that the weight should come off your belly or your thighs. And because part of what you lose is lean mass, it is worth asking your doctor how to protect your muscles while you lose weight.

Ozempic and loose skin

You may have come across the term "Ozempic face". Cleveland Clinic (opens in a new tab) explains that it is not a side effect of the medication itself, but of the rapid weight loss the medication can bring: rapid weight loss lowers the levels of collagen and elastin in the skin, which can lead to sagging. The same article notes that, just as weight loss can cause sagging skin on the stomach and arms, the same can happen in the face.

Cleveland Clinic's advice is to aim for slower weight loss, about one to two pounds (roughly 0.5–1 kg) per week, to eat enough protein to help build muscle as you lose fat, and to combine the medication with a healthy diet and exercise. (Source: Cleveland Clinic (opens in a new tab))

What about retatrutide?

Retatrutide is a newer medicine that is still in development, and it is not approved. According to Drugs.com (opens in a new tab), retatrutide is an investigational medicine that has not been approved by the US Food and Drug Administration (FDA), and on 23 July 2026 Lilly announced that it plans to submit an application to the FDA in the first quarter of 2027. A planned application is not an approval.

Where SLIM fits

Weight-loss medication and SLIM Body do different jobs. Medication, prescribed by your doctor, works on your appetite and your overall weight. SLIM Body works on shape: the areas you choose, such as belly, waist, thighs or arms. In one 45-minute session your fat cells open and shrink, your muscles are activated, and SLIM Body supports skin tightening, so it can be a useful companion while you are losing weight with your doctor's support. Please tell us before booking if you take regular medication. In many cases a short note from your doctor is all we need. Your trial starts with a BIA body analysis and measurements, and we measure again before you leave. Lose 2–8 cm total in your SLIM Body trial — or your money back. (Source: NHS: semaglutide (opens in a new tab))

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