Doctor explains exactly what happens to your body during first month on Mounjaro weight loss jab

A doctor has explained how the body adjusts to the weight-loss drug Mounjaro during its first month of use.

Weight loss drugs have soared in popularity in recent years, with people hoping for a hand in shedding some pounds.

Mounjaro, from US pharma giants Eli Lilly, is a dual GIP and GLP-1 receptor agonist and works by regulating blood sugar and appetite, as well as improving how the body responds to insulin.

It's injected once a week, starting out at 2.5 mg, with the dose gradually upped to a maximum of 15 mg. Mounjaro can curb hunger, helping to shrink our stomachs and lose weight.

Dr Donald Grant, GP and Senior Clinical Advisor at The Independent Pharmacy has broken down what people might expect during their first month on Mounjaro. Though bear in mind everyone reacts to the medication differently, so experiences can differ.

Week one on Mounjaro

Mounjaro users start out with a 2.5 mg dose for four weeks (Getty Stock Image)

Dr Grant notes people tend to feel 'a little nervous' before starting the weight-loss drug.

But getting clued up can help put your mind at ease.

"Before people take their first dose, it’s important to read the instructions carefully so they know exactly how the injection works," he says.

Once the drug is injected, it can take anywhere between eight and 72 hours to reach 'peak levels' in our systems.

But, Dr Grant warns, 'some may notice a decrease in appetite even sooner.'

He adds: "People could also begin to experience common Mounjaro side effects like headaches, nausea, diarrhoea and indigestion, although these should ease as the body gets used to the medication."

Week two on Mounjaro

Cravings might start fizzling out (Nicoletaionescu/Getty Images)

Week two means a second dose on the medication - and we might notice it where cravings are concerned.

“After people take their second dose, they could begin to find fatty and sugary foods less tempting and that they feel fuller for longer," Dr Grant explains.

While this is usually a good sign, it does run the risk of some dangers. “As people are probably eating and drinking less, they could become dehydrated or tired more easily. I recommend reducing these effects by eating a healthy, balanced diet and drinking plenty of water."

Dr Grant adds: "Some may notice some of the same side effects that they experienced in week one - though they may be milder as the body adjusts to the medication."

Week three on Mounjaro

Healthy habits will help keep the weight off (Getty Stock Photo)

By the third dose, people’s bodies will be starting to adjust to Mounjaro, with their side effects becoming 'milder or disappearing completely.'

Although Dr Grant warns some may find that their symptoms are more 'stubborn.'

“Though some may not notice any weight loss just yet, they could find that their appetite is consistently reduced and they’re eating less than normal," he adds. "It takes time to see results, especially on the lowest dose of the treatment."

Completing a month on Mounjaro

Doses increase after four weeks (Peter Dazeley via Getty Images)

The first month might be a bit of an adjustment, but hopefully your body is used to the medication by now.

People might be hoping to see the results of the weight loss drug right away - but Dr Grant warns us to look at the bigger picture.

He explains: “On average, people taking Mounjaro lose less than four percent of their starting body weight by the end of the first month."

So ultimately, there is some movement that would keep momentum and motivation going.

“However, while weight loss is of course a major consideration, it’s even more important that people establish healthy eating patterns and increase exercise levels," Dr Grant adds. "Making these lifestyle changes now will help people lose weight and keep it off long-term.

Side effects of concern

Dr Grant adds that most side effects are 'mild' but some that could be serious require medical attention

“If you experience: rash, itching or hives, swelling in the lips, tongue or throat, shortness of breath, trouble breathing or wheezing, or dizziness or fainting, then it's important to speak to a doctor straight away."

He adds: “It is essential to speak to a licensed medical professional before starting any weight loss medication. They can provide personalised, expert guidance, assess potential risks and ensure that the chosen treatment is safe and suitable for specific health needs.”

UNILAD has contacted Eli Lilly for comment.