The real reason your Mounjaro has stopped working: DR PHILIPPA KAYE reveals diet supplement that can turbocharge the jabs, the part of the body you MUST inject and why it may be time to switch to a different weight loss drug

Weight loss injections are some of the most revolutionary drugs of modern times, but they are not perfect.

More than 2.5 million Britons now use Mounjaro and Wegovy, which can help obese patients lose up to a fifth of their body weight in a year.

Data shows that the majority of these patients are women who pay for appetite suppressant injections through private clinics. This will come as little surprise to any woman over a certain age; We’re all too familiar with the pressure to stay thin even as the demands of midlife pile up.

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For patients, these medications can be life-changing and allow them to lose more weight than they thought possible.

First, there are all the health benefits that come with losing weight, including a reduced risk of many types of cancer, heart disease, and dementia.

And there are also mental health benefits for people who experience obesity along with all the shame and stigma associated with the condition.

For all these reasons, many people feel devastated when weight loss pills don’t work. This phenomenon, known as the weight loss plateau, affects many Mounjaro and Wegovy patients, usually after several months of treatment.

At this point, patients have usually reached the maximum dose (which gradually increases over time), which means they may feel like there’s nothing else they can do to restart weight loss.

It’s very common for women to feel like they’ve ‘failed’ in their weight loss journey and even worry that they may start gaining the weight back.

Of course, it is important to remember that losing any percentage of body weight will have a huge positive impact on long-term health and will likely extend patients’ lives.

Moreover, weight loss, which many patients now consider a failure, such as a loss of ‘only’ 10 percent, was often unthinkable before the advent of these drugs.

However, we have good news for those who have experienced this difficult experience. I tell my patients who come to me with this problem that there are some simple steps that can help.

Change injection point to speed up injections

Most weight loss injection patients tend to inject themselves in the same spot; but it is possible that changing the location will help them break through a plateau.

These are not simple drugs. First of all, it needs to be stored in the refrigerator and used before its expiration date. Leaving the shots out of the refrigerator for too long before starting or taking them after the expiration date may affect their effectiveness.

Likewise, weight loss medications must be injected into the correct part of the body. To have an effect, they must enter the skin, not the muscles.

Most weight loss injection patients tend to inject themselves in the same spot; but it is possible that changing the location will help them break through a plateau.

For this reason, companies recommend injection into the abdomen, thigh, or upper arm (when given by another person).

Studies show that the drug’s effectiveness appears to be consistent across all these sites. However, anecdotally some of my patients have noticed a greater effect on their appetite when they inject into one part of the body than another.

Moreover, repeated injections tend to thicken the skin. Therefore, patients should not forget to rotate the area where they inject (for example, change the specific location in the abdomen).

One reason for doing this is to prevent skin irritation, but this thickened skin likely also prevents the body from absorbing most of the medication, weakening the medication’s effect.

Consume plenty of this important nutrient to lose weight

Eating a diet high in fiber can be crucial in overcoming a plateau.

These medications work by reducing appetite and slowing down the stomach, so patients feel full longer and eat less. However, it is still possible to eat more than you think.

There is good evidence that fiber-rich foods can help suppress appetite and prevent overeating and snacking.

First, many patients can eat smaller portions while continuing to consume high-calorie foods and beverages.

A patient of mine with Mounjaro told me that they still eat chocolate digestifs for breakfast, just a little less than before.

I also regularly hear from weight loss pill users who say they are fueling themselves with snacks throughout the day.

But it’s also important for those at Mounjaro and Wegovy to make sure they consume enough fiber.

Fiber is a form of carbohydrate found in fruits, vegetables, nuts, seeds, legumes and whole grains.

Studies have shown that it can help with stomach problems, regulate blood sugar levels, and even reduce the risk of bowel cancer. But there is also good evidence that a fiber-rich diet can further suppress appetite and help avoid overeating and snacking.

Despite this, nine in ten Britons don’t get enough of the recommended 30 grams of fiber a day. A 2025 study examining diabetic patients who received injections found that none of them consumed enough fibre.

Changing the needle can put patients in a difficult situation

Mounjaro may be a more effective injection on paper, but some patients report that switching to the less potent Wegovy can help them get past the plateau.

Of the two, Wegovy has been around the longest and has the strongest evidence supporting its use. There is now very strong data showing that it improves heart health significantly more than Mounjaro ever could. It is also a cheaper option.

GP, author and broadcaster Dr. Philippa Kaye

However, it is undeniable that Mounjaro leads to greater weight loss on average. The injection, also known as tirzepatide, typically leads to a reduction in body weight of about 21 percent, while Wegovy, or semaglutide, leads to only a 15 percent reduction.

This is why Wegovy patients who have reached a weight loss plateau often consider switching to Mounjaro.

However, I have also heard from patients who say that switching from Mounjaro to Wegovy may also have positive effects. This may have more to do with psychology than anything else.

When patients change weight loss medication, they have to start again with the lowest dose and gradually increase it. This can give patients a sense of fresh start; because as the dose increases, they will lose their appetite for a short time before the appetite suppression kicks in again.

Of course, it is important for patients to continue to eat reasonably and get plenty of exercise during this transition period to prevent weight gain.

Stubborn weight may be due to an undiagnosed condition

There are a number of medical reasons why patients, especially women, may have difficulty losing weight due to injections.

The most common of these is polycystic ovary syndrome (PCOS), a hormonal condition that can cause weight gain, irregular menstrual periods, and fertility problems.

Anyone suffering from these symptoms should speak to their GP, who can look for signs of this condition by ordering blood tests and scans if necessary. There are a number of treatments available, including the metformin tablet, which helps regulate blood sugar levels and can promote weight loss.

Stubborn weight can also be caused by a condition called hypothyroidism. This is where the thyroid, the butterfly-shaped organ in the neck, does not produce enough important hormones. Symptoms include fatigue, sensitivity to cold, constipation, low mood, and weight gain.

Hypothyroidism can also be diagnosed with a blood test performed by a general practitioner. The treatment is also quite simple; a daily tablet called levothyroxine, which replaces lost hormones.

It is important to consider whether the weight loss plateau is due to prescription medications.

It is known that especially antidepressants, steroids and antipsychotics trigger weight gain or, most importantly, prevent weight loss.

Although most people currently taking weight-loss medications pay for them privately, they can talk to their NHS doctor about any of these problems.