By Dr. Asnat Raziel, bariatric surgeon specializing in obesity treatment, metabolic health and healthy longevity; Director of the Multidisciplinary Center for Obesity Treatment, Assia Medical, Assuta Ramat HaChayal, Tel Aviv
Before starting Wegovy and Mounjaro: the drugs that changed the rules of the game
Before starting Wegovy and Mounjaro, it helps to get the facts straight. People who use them report impressive weight loss, less hunger and more control. However, there are also side effects, emotional changes and important questions to ask. In this article, I have gathered what I explain to every patient at our first meeting.
Wegovy contains semaglutide, and Mounjaro contains tirzepatide. Both mimic natural hormones of the digestive system. These hormones increase fullness, reduce hunger and change the way the body regulates sugar and energy. What does this mean in practice?
- Less food noise, the constant thoughts about food.
- Less snacking between meals.
- Steady weight loss.
- Better blood sugar and cholesterol levels.
- For some patients, more energy and a return to physical activity.
One patient put it this way: “For the first time in my life, I feel that my body is working with me, not against me.”
Before starting Wegovy and Mounjaro: who the treatment is for
The treatment is intended for adults with a BMI (body mass index) of 30 or higher. It is also suitable for a BMI of 27 or higher when there is a related condition, such as high blood pressure, diabetes or sleep apnea. Wegovy is also approved for teenagers from age 12. On the other hand, these drugs must not be used during pregnancy, or when there is a personal or family history of medullary thyroid cancer. That is why the first visit includes a full medical workup, blood tests and a conversation about eating habits.
How much weight do people really lose?
The numbers are impressive, and they match what I see in my clinic. In the SURMOUNT-1 trial, Mounjaro at 15 mg led to an average weight loss of 20.9% after 72 weeks. For example, a person who weighs 100 kg could lose about 21 kg. In the STEP 1 trial, Wegovy led to an average weight loss of 14.9% after 68 weeks. In other words, a woman who weighs 90 kg could lose about 13 kg. A detailed comparison appears in my article on Mounjaro vs. Wegovy.
Before starting Wegovy and Mounjaro: increase the dose patiently
With both drugs, you start at a low dose and increase it gradually. According to the Wegovy prescribing information, you start at 0.25 mg a week and increase every four weeks up to 2.4 mg. Today, the dose can be raised to 7.2 mg if needed. According to the Zepbound prescribing information (Zepbound is the US brand name of tirzepatide for obesity), you start at 2.5 mg. After that, the dose goes up by 2.5 mg at least every four weeks, up to 15 mg. So it is important not to rush: a slow increase reduces side effects.
Beyond weight loss: real health benefits
These drugs are not “cosmetic.” They affect many systems in the body. In a large trial, Wegovy reduced the risk of heart attack, stroke and cardiovascular death by 20% in people with heart disease. Later, Mounjaro also showed heart protection, and on August 28, 2026, the FDA approved it for cardiovascular risk reduction. My article on the SURPASS-CVOT trial and Mounjaro’s heart benefits covers this in detail.
In addition, both improve blood sugar control and are especially suitable for people with type 2 diabetes. They also reduce liver fat. Wegovy is even approved for treating inflammatory fatty liver disease with liver scarring. A simple example: a 52-year-old woman with prediabetes, slightly high blood pressure and belly fat. She may not only lose weight, but also lower her future risk of heart disease.
Common side effects
Most side effects are mild and pass, but it is important to know them. According to the Wegovy prescribing information, nausea occurred in 44% of patients, diarrhea in 30%, and vomiting and constipation in 24%. In the Zepbound prescribing information, by contrast, nausea occurred in 25% to 29% and diarrhea in 19% to 23%. These were different trials, so the comparison between them is indirect. In most cases, side effects appear mainly while the dose is being increased. How can you reduce them?
- Eat slowly and in small portions.
- Avoid fatty meals.
- Drink plenty of water.
- Do not increase the dose too fast.
An example from my clinic: a patient suffered from nausea for two weeks. We moved her injection to the evening, made her meals smaller and added drinks with electrolytes. Within a short time, the nausea was gone. You will find more tips in my article on Wegovy side effects.
What about the rare risks?
Pancreatitis is rare. Even so, severe pain in the upper abdomen requires an immediate call to your doctor and stopping the treatment. Extreme slowing of stomach emptying is also rare. It shows up as a severe feeling of fullness, nausea and vomiting. As for the thyroid, the warning is based on animal studies. In humans, a link to thyroid cancer has not been proven. Most patients go through treatment safely, but medical follow-up is a must.
What about mood?
The internet is full of stories about depression and anxiety, but the science paints a different picture. In January 2026, the FDA asked to remove the warning about suicidal thoughts from the labels of these drugs. An analysis of 91 trials with 107,910 participants showed no increase in risk, including for depression or anxiety. Still, a small number of patients do experience mood changes. Possible reasons include hormonal changes, less pleasure from food and fear of regaining weight.
An example from my clinic: a patient developed anxiety after switching from Wegovy to Mounjaro. We ran blood tests, slowed the dose increases and added vitamin B12 and vitamin D. Over time, the feeling passed. I discuss this further in my article on GLP-1 drugs and depression.
Before starting Wegovy and Mounjaro: protect your muscles
Here is the truth that usually goes unsaid: any rapid weight loss also takes away lean body mass, not only with these drugs. According to a comprehensive review, in some studies lean body mass made up 40% to 60% of the weight lost. In other studies, it made up about 15% or less. It is worth knowing that lean body mass also includes water, organs and bone, not only muscle. In addition, the “Ozempic face” effect, a hollowed-out look, comes from the loss of fat under the skin. How do you protect your muscles?
- 1.2 to 1.6 grams of protein per kg of target weight.
- Strength training at least twice a week.
- A moderate rate of weight loss, not a drastic one.
An example from my clinic: a patient lost 12 kg. Thanks to three strength workouts a week and daily protein, he lost only 1.5 kg of muscle. You can read more in my article on protecting muscle mass during treatment.
What happens when you stop
Obesity is a chronic disease, so stopping treatment has consequences. In the STEP 1 extension, participants stopped Wegovy. Within a year, they regained about two thirds of the weight they had lost. In the SURMOUNT-4 trial, people who switched from tirzepatide to placebo gained 14.0% of their weight within 52 weeks. By contrast, those who continued treatment lost another 5.5%. That is why it is worth planning the way forward with your doctor in advance. A detailed guide appears in my article on stopping weight loss medication.
So is it right for everyone?
No. These drugs do not replace a healthy lifestyle, and they are not a magic fix. They are a powerful tool, but it has to be used wisely:
- Personalized nutrition.
- Regular physical activity.
- Close medical follow-up.
- Emotional support as needed.
People who take a holistic approach achieve the best results for years to come.
Bottom line: before starting Wegovy and Mounjaro
Wegovy and Mounjaro are among the most effective treatments available today for weight loss and better health. They can change lives. However, before starting Wegovy and Mounjaro, it is important to understand the full picture: the benefits, the risks, the effect on mood and the importance of protecting your muscles. Ultimately, a thoughtful approach with professional support and a comprehensive plan leads to impressive weight loss and good health over time.
The information in this article is general and does not replace personal medical advice.
References
Tirzepatide Once Weekly for the Treatment of Obesity
Once-Weekly Semaglutide in Adults with Overweight or Obesity
WEGOVY (semaglutide) – Prescribing Information
ZEPBOUND (tirzepatide) – Prescribing Information
Changes in lean body mass with glucagon-like peptide-1-based therapies and mitigation strategies
