Weight Gain during Cancer Treatment

By Michele Szfranski, MS, RD, CSO, LDN


When I talk with people who have gained weight during their cancer treatment, they are often shocked. For people who lost considerable weight before their diagnosis and then felt better once their treatment started, weight gain can be a welcome change. But more often I speak with people who were at a healthy weight or overweight before treatment and did not realize that their treatment might cause some weight gain. [more]

Causes of weight gain

Many of the cancer patients with hormone based cancers like breast or prostate I speak to are surprised when they find they have gained weight after their treatments. Men on anti-androgen (hormone deprivation) therapy often gain weight in the first year of treatment. Women treated with adjuvant chemotherapy or who experience onset of menopause are most likely to experience weight gain.

Gaining weight after being diagnosed can give these patients a higher risk of the cancer returning. In fact, a recent study showed that men who gained about 5 pounds (2.2 kg) in the years after prostatectomy had higher rates of recurrence than those with stable weight. And for breast cancer, studies also suggest that weight gain after treatment can increase recurrence risk and decrease survival.

There are many factors that might contribute to weight gain with treatment of any cancer. Fatigue, a common side effect of chemo and radiation, can lead to less physical activity, which means fewer calories burned. Many people who have nausea, another common side effect, find that always having something in their stomach can help to keep it settled. Others eat more when they feel stressed out, and if having cancer isn’t stressful, I don’t know what is. Hormone changes or medications may cause people to feel hungry or retain water. Well-meaning loved ones may encourage patients to “eat, eat, eat” out of fear that they may lose weight.

How can this weight gain be prevented? 

Weight gain leading to obesity can also contribute to high blood pressure, cardiovascular disease, diabetes, and even other cancers. But there are things patients can do to try to prevent or minimize weight gain during treatment.

  • Be proactive. Ask your doctor if your type of chemotherapy is likely to cause weight gain. Knowing can help you keep an eye on behaviors and patterns that might pack on the pounds. A food and activity journal to track eating and exercise could help, too. There are lots of free programs on the internet or apps available for smart phones that can even scan your food labels.


  • Incorporate physical activity when you can. Staying active may combat fatigue and can also help control side effects like constipation and nausea. ACS guidelines for cancer survivors recommend incorporating at least 150 minutes of moderate physical activity per week. (Click on the link for information specific to cancer survivors.)


  • Eat a diet full of fruits, vegetables, and whole grains. This kind of diet can help manage weight and also help reduce risk of recurrence of some cancers as well. Aim for at least 2½ cups of fruits and vegetables daily. Add a serving of legumes like peas or beans; they are a great protein source and the fiber they contain can help keep you full.


  • Eat lean protein, which can leave you feeling satisfied for longer than starchy foods. If you are feeling more hungry than usual make sure to incorporate some lean protein sources like low-fat dairy (yogurt, cheese, cottage cheese), lean meats (chicken, turkey, fish, and occasional red meat like sirloin), as well as beans and peas. Nuts and nut butters can also be good sources of protein, but they are very high in calories, so portion size is important.


  • Stay hydrated. Often we misinterpret our thirst cues as hunger, so try to drink something first. Doctors often encourage patients to drink more fluids than usual during treatment, so be sure to choose low-calorie or no-calorie beverages. And don’t add a canned nutritional supplement unless the doctor recommends it, or if see you are losing weight.

Planning meals around your treatment schedule is important too. Make sure to shop when you are feeling well and are less likely to be tempted by high calorie and fatty foods. Take advantage of foods like frozen and pre-washed and -chopped fruits and vegetables. Cook when you are feeling relaxed and most energetic — if you wait until you are run down you are more likely to make poor choices. And always keep an eye on portion sizes, especially in restaurants.  Don’t be afraid to mention your dietary concerns to those who cook and shop for you; after all they are doing it because they care about your well-being.

Resources to help

Many communities and cancer treatment centers have diet and exercise programs and classes free for their patients. Be sure to ask your treatment team if anything like this is available in your area, or call the American Cancer Society at 1-800-227-2345. While you’re on the phone, ask about several fantastic publications to help you manage your weight after treatment, like Cooking Smart. This booklet can walk you through our eating guidelines to help you eat healthy, including low-fat cooking techniques and recipes. The Living Smart booklet discusses guidelines for physical activity. The American Cancer Society bookstore also has several publications, including cookbooks that can help you manage your cancer symptoms (like weight gain). Or, if you prefer some online resources, here is some information on nutrition for people with cancer and how to eat healthy.

2 thoughts on “Weight Gain during Cancer Treatment

  1. Wow I was surprised to read this i had cancer last year and I gained a lot of weight & that advice is really good I wish I would have known that a year ago but I hope other patients can benefit from this.

  2. One thing cancer will cause you to do is not be so active. This certainly plays a role in going from a normal day of burning calories, to laying in bed all day long. My Mother has been doing chemotherapy for a 3 years, and she is always conscious about her weight. I find this silly, but she always has trouble maintaining her weight during chemotherapy. She swears it is from constant ativan use.

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