By Dr. Asnat Raziel, specialist in obesity treatment, metabolic health and healthy longevity; Director of the Multidisciplinary Center for Obesity Treatment, Assia Medical, Assuta Ramat HaChayal
Weight loss medications: who are they for?
Weight loss medications are now a central part of obesity treatment, not a short-term magic fix. They act on the mechanisms of hunger and fullness, and they help the body stop “fighting” weight loss. However, no single drug suits everyone. The choice depends on other conditions, other medications, future plans and personal preferences.
According to the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), treatment usually suits adults with a BMI of 30 or more. In addition, it also suits people with a BMI of 27 or more who have a weight-related condition, for example high blood pressure or type 2 diabetes. BMI is body mass index, meaning weight in kilograms divided by height in meters squared.
How do the drugs work in the body?
Obesity is not a problem of willpower. It is a chronic disease in which the brain defends a higher weight. After a diet, hunger hormones rise and fullness weakens. That is why most people regain the weight, even when they try very hard.
The new drugs mimic natural gut hormones, such as GLP-1. This hormone slows stomach emptying and signals to the brain that we have eaten enough. As a result, food takes up less space in our thoughts. I explain this in more depth in my article on how obesity medication works.
Weight loss medications available today
Today there are several families of drugs. They differ in effectiveness, in how you take them and in their side effects.
Weekly GLP-1 injections
Semaglutide, sold as Wegovy, is given as an injection once a week. In the STEP 1 trial, participants lost an average of 14.9% of their weight over 68 weeks, compared with 2.4% in the placebo group. Tirzepatide, sold as Mounjaro, acts on two hormones: GLP-1 and GIP. In the SURMOUNT-1 trial, the 15 mg dose led to an average loss of 20.9% over 72 weeks, compared with 3.1% in the placebo group. I detailed the differences between the two injections in my article on Mounjaro or Wegovy.
Weight loss medications in pill form
For people who dislike injections, there are now pills too. In the US, regulators recently approved the Wegovy pill (oral semaglutide) and Foundayo, whose active ingredient is orforglipron. According to the report on Foundayo’s approval, participants in a 72-week trial lost an average of 11.1% of their weight, compared with 2.1% in the placebo group. In other words, the pills work, but usually more modestly than the strongest injections.
Older drugs
Xenical, whose active ingredient is orlistat, reduces fat absorption in the gut. It is a relatively safe drug, but its effect is modest. You will find more details in my page on Xenical for weight loss. There is also a combination of naltrexone and bupropion, which acts on the brain’s reward centers. I wrote about it in my guide to Mysimba.
How to choose weight loss medications personally
At the first visit, I do not start with the drug. Instead, I start with the person in front of me. These are the main questions that guide the choice:
- Other conditions: diabetes, heart disease, fatty liver or sleep apnea change the order of priorities.
- Regular medications: some drugs raise weight, and sometimes they can be replaced.
- Pregnancy plans: do not take weight loss drugs during pregnancy or while trying to conceive.
- Medical history: past pancreatitis, or a family history of medullary thyroid cancer.
- Preferences: a weekly injection or a daily pill, and also the ability to pay over time.
Cost is also a practical consideration. In Israel, all four health funds (Clalit, Maccabi, Leumit and Meuhedet) provide Wegovy and Mounjaro through their supplementary insurance plans, at a discount of about 50%. The health funds publish updated prices on their websites.
For example, for a patient with heart disease, data on heart protection matter. In contrast, for a patient with sleep apnea, tirzepatide is also approved in the US for obstructive sleep apnea (as Zepbound), for moderate to severe disease in adults with obesity. In addition, for someone who takes many drugs, it is important to review the whole list.
The training of the treating doctor also matters. In practice, a good match requires knowing all the options, not just the best-known drug.
Side effects and safety
The common side effects of the injections are nausea, diarrhea, constipation and vomiting. Usually they are mild to moderate, and they appear mainly while the dose is rising. So treatment starts at a low dose and rises gradually. In the SURMOUNT-1 trial, only 4.3% to 7.1% of participants stopped treatment because of side effects.
Even so, in some situations these drugs are off limits. According to NIDDK, people should not use semaglutide or tirzepatide if they have a personal or family history of medullary thyroid cancer or MEN 2 syndrome. You will find a practical guide to coping in my article on the side effects of weight loss drugs.
How long do you take weight loss medications?
According to Mayo Clinic, many people regain some weight after stopping treatment. The reason is simple: the drug treats the disease, but it does not cure it. Therefore, when the drug helps and there are no serious side effects, treatment usually continues for the long term.
There is also an important stopping rule. Suppose weight loss is less than 5% after 12 weeks at the full dose. In that case, NIDDK recommends considering stopping or switching to another treatment. This way, you do not keep paying for a treatment that does not work.
Also, the drug works best together with habits. Protein at every meal and strength training help preserve muscle mass during weight loss. Good sleep and stress management make it easier to persist.
Bottom line on weight loss medications
Weight loss medications are an effective medical tool, based on large trials. Success depends on a personal match: other conditions, other medications, pregnancy plans and preferences. Therefore, it is best to choose treatment together with a doctor who knows all the options, and to keep up regular follow-up.
This article provides general information and is not personal medical advice. For any question about your treatment, please consult your doctor.
Questions and answers
Are weight loss medications suitable for everyone?
No. They are meant mainly for adults with a BMI of 30 or more, or 27 or more with a weight-related condition. Do not use them during pregnancy.
What is the difference between an injection and a pill?
The weekly injections are usually the strongest. Pills are convenient for people who do not want injections, but the average weight loss with them is more modest.
What happens when you stop treatment?
Many people regain some of the weight. So it is important to plan stopping ahead with your doctor, and to keep up healthy eating and activity habits.
When do you decide the drug is not working?
When weight loss is less than 5% after 12 weeks at the full dose. At that point, you consider another treatment.
References
Prescription Medications to Treat Overweight & Obesity – NIDDK
Prescription weight-loss drugs – Mayo Clinic
Once-Weekly Semaglutide in Adults with Overweight or Obesity
Tirzepatide Once Weekly for the Treatment of Obesity
FDA Approves Lilly’s Oral GLP-1 Orforglipron for Obesity – AJMC
