Ozempic, Zepbound, Wegovy, and related weight loss drugs have become some of the world’s most talked about medications in a remarkably short time.
A growing body of research suggests these drugs may also be an important tool in reducing cancer related to obesity and higher levels of body fat.
“There are at least 13 types of cancer we know are linked to obesity, including post-menopausal breast, colon and gastric (stomach), prostate, endometrial, and others,” says Sherry Shen, MD.
Dr. Shen is a breast cancer oncologist at Memorial Sloan Kettering Cancer Center (MSK) who studies the relationship between obesity, metabolic health, and cancer. Her research includes a study published in August 2025 that found these drugs helped breast cancer patients lose weight. Weight gain is a common side effect during breast cancer therapy that can lead to worse outcomes including poorer cardiovascular health.
“These medications look to be promising in potentially reducing the number of people who are diagnosed with these obesity related cancers,” says Dr. Shen. “It’s projected that by 2030, severe obesity is going to be the dominant weight category in many states across the US. If these drugs can help lower the cancer risk associated with obesity, that’s really important.”
Dr. Shen cautions that these are early days for these medications with much research yet to do. However, “Many patients want more information about these medications,” she says. Here, Dr. Shen provides answers to the questions patients ask most often.
What are these new weight loss drugs?
These weight loss medications are known as GLP-1 agonists because they activate the GLP-1 receptor that stimulates the production of insulin, which regulates blood sugar, as well as delivering several other effects.
Because they affect insulin, these medications were originally developed to treat diabetes. Ultimately, their weight loss effect was recognized.
The best known right now are:
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Semaglutide (generic name):
- Wegovy: obesity weight loss brand name
- Ozempic: diabetes brand name
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Tirzepatide (generic name):
- Zepbound: obesity weight loss brand name
- Mounjaro: diabetes brand name
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Liraglutide (generic name):
- Saxenda: obesity weight loss brand name
- Trulicity: diabetes brand name
It’s important to know that a cancer diagnosis by itself does not qualify as a reason for treatment with these drugs under the current Food and Drug Administration (FDA) indication (guidance).
The FDA currently requires either:
- Body Mass Index (BMI) equal to or greater than 30
- Body Mass Index (BMI) equal to or greater than 27 plus a co-morbidity including high blood pressure, high cholesterol or type 2 diabetes.
MSK is conducting research to determine if cancer should be added as a reason for treatment with these medications.
Do they really help people lose weight?
They do, and the weight loss is even better when combined with healthy lifestyle choices.
There have been weight loss drugs for a long time, but they provided only moderate weight loss and had a lot of side effects. This new class of drugs are much more successful in treating obesity and inducing weight loss and have manageable side effects.
How do Zepbound, Wegovy and similar weight loss drugs work?
Think of these weight loss drugs as constantly putting you in a post-meal state, where you feel full and aren’t hungry, so you don’t feel the urge to eat. This happens through several different mechanisms, some of which are not fully understood. These include the following hormones:
- Ghrelin: The drugs regulate the hormone ghrelin, which is produced in the stomach and is basically the hunger hormone that signals to your brain that you need food.
- Leptin: This hormone is the opposite of ghrelin. It is produced in your fat cells and tells your brain that you’re full and don’t need any food.
- Insulin: A person’s insulin level is also regulated by the medication and slows down the working of your stomach, called gut motility, so you feel full longer.
All these factors work together, and there is direct stimulation of the brain telling you that you don’t have cravings and feel full — just like after a big meal.
How does weight loss affect cancer risk?
We know obesity — and even high body fat — puts people at greater risk for multiple forms of cancer. It can be a challenge to get a healthier body composition for many people, and these medications can help jump-start the effort.
By reducing food cravings, these drugs can lower the consumption of highly processed food, which is particularly bad for overall health, including cancer risk. There is also evidence to suggest cravings for alcohol are lowered.
Lifestyle modifications are crucial — a medication alone is not a long-term fix. For people with cancer, I especially recommend a high-fiber, plant-forward diet and consistent exercise.
For people with breast cancer, the MSK Healthy Living Program helps to implement these lifestyle recommendations. Getting started with those kinds of lifestyle changes may now be easier for some people thanks to an appropriate use of the new weight loss medications.
Can Zepbound, Wegovy, and similar weight loss drugs help people diagnosed with cancer?
We simply don’t have the data for somebody who has just been diagnosed with cancer. I also worry about anything that could disrupt urgent treatments like chemotherapy or radiation therapy or immunotherapy at the beginning of cancer therapy.
For instance, there can be gastrointestinal side effects with these weight loss drugs, and that could interfere with some cancer treatments.
On the other hand, if someone has been on cancer treatment for a couple months and is tolerating it well, it may be fine to use these weight loss medicines.
For people on long-term hormonal therapy, we’ve anecdotally seen that use of concurrent weight loss medications appears to be feasible. In fact, some patients quit taking their hormone therapy because it can be associated with weight gain, and the new weight loss medications might be a solution.
That is why I’m encouraged by the research I led that shows people with breast cancer did in fact lose weight while taking GLP-1 medications, when we would generally expect them to gain unwanted weight related to breast cancer treatment.
Of course, anyone on cancer therapy and interested in starting a weight loss medication should first check with their oncologist.
We definitely need clinical trials to determine the safest and most effective approach to medical weight loss in the setting of cancer treatment.
In the cancer setting, who could these medicines help best?
- People who want to prevent cancer in the first place, if they are obese or significantly overweight.
- People who have been on cancer treatment for quite a while or are looking to reduce the chance of recurrence after finishing treatment by reducing their body weight.
Of course, people would need to discuss the best option with their care team.
What are the side effects of these weight loss drugs?
Gastrointestinal Side Effects
There can be gastrointestinal side effects, including nausea and vomiting for some people, which are usually manageable.
Concerns about Increased Cancer Risks
- Kidney Cancer
Some research has found a small increased risk of kidney cancer for people taking GLP-1 weight loss drugs. Discuss the risks with your doctor.
- Thyroid Cancer
A very low risk of thyroid cancer, specifically medullary thyroid cancer, has been associated with use of these drugs, and this is of particular concern to people already diagnosed with cancer.
Other recent research suggests that patients with another form of the disease—called differentiated thyroid cancer—GLP-1s do not increase risk of the disease recurring or progressing.
People who are good candidates for weight loss medications often have health risks that are greater than the low risk of thyroid cancer. Nonetheless, this is an important risk/benefit discussion for people to have with their doctor.
Suicidal Thoughts
Research in Europe suggested these drugs could lead to suicidal thoughts, perhaps because these medications affect brain pathways responsible for hunger signaling.
However, this side effect was rare, and the FDA concluded the drugs presented no concerns about suicidal ideation. If a person taking these drugs notes a depressed mood or change in anxiety level, they should discuss it immediately with their provider.
If you or someone you know may be experiencing a mental health crisis or contemplating suicide, call or text 988. In emergencies, call 911, or seek care from a local hospital or mental health provider.
KEY TAKEAWAYS
- Popular weight loss drugs including Zepbound and Wegovy may help reduce the risk of cancer linked to obesity, which has been identified in at least 13 forms of cancer, including breast, endometrial, colon, gastric, prostate and more.
- The new weight loss drugs work by making people feel full and signaling the brain to stop eating.
- Side effects including gastrointestinal problems needed to be considered. Some research also suggests the drugs may slightly increase the risk of some forms of cancer, including kidney and thyroid cancers.
