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Man kayaking and holding up his paddle in triumph over his new healthier lifestyle during and after cancer treatment

10 Tips to Combat Weight Gain During Cancer Treatment

Reading time | 5 mins
"You may not see the scales tip in your favor right away after cancer treatment. I realized I was in a marathon, not a sprint," writes Todd Seals.


Weight gain is common for people with breast or prostate cancer undergoing medical and/or hormonal treatments.

Many oncologists have told me that they prefer patients put on a few pounds. But significant weight gain may lead to health issues such as high blood pressure, diabetes, and heart disease.

Although I struggled with muscle loss, initially I had zero interest in exercising when I began cancer treatments. I eventually found solutions that helped me to keep my weight in check.

Over the last 13 years, my weight has never varied by more than a few pounds. More importantly, I feel good.

Here’s why cancer treatments can cause weight gain and how I fought it.

My weight gain during cancer treatment

There are several causes for weight gain during cancer treatments.

Chemotherapy create changes in your appetite, or even make you feel nauseous.

Cancer medications may slow your metabolism and lead to water retention and fat deposits.

I had prostate cancer. I was put on androgen deprivation therapy (ADT) after my prostate cancer diagnosis.

For men like me, ADT causes weight gain. Research suggests that 70 percent of men who undergo ADT gain on average nearly 5 pounds during the first 6 to 18 months of treatment.

I gained 15 pounds in the first year of treatment. I wasn’t concerned that I was putting on weight at first. I had been sick for a long time prior to diagnosis. I needed to gain a little weight to look healthy.

But after the first 10 pounds, I realized I needed to make changes to maintain a healthy body mass index. I found that weight gain stabilized after the first year.

Cancer makes establishing a consistent workout routine difficult. I didn’t always feel good for a couple of days after treatment. When I felt better, I still had fatigue. It was time for treatment again by the time I worked through the fatigue. It’s a vicious cycle.

How to keep weight gain in check

Unfortunately, there's no magic bullet to maintain a healthy weight, but a few strategies may help.

1. Diet and exercise

Exercise helps minimize muscle atrophy and weight gain.

I found that exercising was the last thing I wanted to do when I began treatment. I felt fatigued and sometimes nauseated. Ironically, exercise can sometimes help with fatigue.

A healthy diet is also key to minimizing weight gain during cancer treatments. But even with the best intentions, many of us aren’t sure where to start when it comes to eating a healthy diet.

I understand just how difficult it can be to maintain a new diet and exercise program when you’re getting treatment for cancer.

Here are the tips that helped me to manage my weight during cancer treatments.

2. Understand your nutritional needs

I was lucky to have a nutritionist on staff at my place of employment. He helped me to understand how my body had changed due to cancer treatments. He also helped me to build a healthy diet around my new nutritional needs.

If you aren’t already working with a nutritionist, ask your doctor to refer you to one. A nutritionist can help you to adjust your diet to meet your needs, so you not only limit weight gain but feel better.

3. Eat in moderation

My nutritionist taught me that my metabolism had slowed and that I now needed a lower calorie intake. I learned that moderation was key to eating healthily while undergoing cancer treatment.

4. Choose fresh over packaged

I learned that a lot of the packaged food sold at the grocery store has many nutrients processed out of it, and sugar, salt, and fats added to it.

Ultra-processed food may alter our hunger hormones and cause us to eat too many calories, which leads to weight gain. I choose fresh foods when possible.

5. Don’t skimp on a few key nutrients

My nutritionist suggested that I eat at least 100 grams of protein a day to keep from losing muscle mass.

Protein helps our bodies to build and maintain muscle. It also keeps you feeling full to control weight. The amount of protein you’ll need will vary. A nutritionist can help you figure out a goal that’s right for you.

My nutritionist told me to be sure and get enough fiber. Fiber helps keep things moving through your digestive system. It also keeps you feeling fuller for longer after you eat so you to eat less over time.

I also learned that healthy fats, such as those found in nuts, avocados, and fatty fish, are just as important to your diet needs as protein or carbohydrates. They give you energy and help you to feel full to maintain a healthy weight.

Finally, calcium and vitamin D are important to keep bones healthy. They’re especially essential since hormone therapy makes your bones weaker. I started drinking vitamin D-fortified orange juice. Other good sources include fatty fish and fortified dairy.

6. Start your exercise program slowly

I was a long-distance runner prior to developing cancer. I’d completed many marathons and half-marathons. I once even finished a marathon with a time good enough to qualify for the Boston Marathon!

Lung metastasis took away my ability to run long distances. But it didn’t take away my ability to walk or ride bicycles. I discovered that it doesn’t take much physical activity to begin to feel better.

Consult with your doctor before beginning any exercise program. Start slow but be consistent when you start your exercise routine. Don’t do more than your body can handle.

Try to move just a little bit each day. It wasn't easy at first. Those early walks were no more than a quarter-mile. But we did it every evening.

7. Build on your success

Build on duration and difficulty as you have more stamina.

My walks became longer with time. I began to feel better and have more energy. I started looking forward to them. We started walking farther after a couple of weeks. I later added hand weights, distance, and hills. These days, our walks average about 3 miles.

8. Add in resistance training to build muscle

Research suggests that resistance training helps reduce both muscle loss and fat gain.

Today, getting exercise is a way of life for my wife and me. We don't have a set schedule or routine at the gym. We just try and do something every day. We’ve thrown cycling and kayaking into the mix. I’ve found that kayaking helps me to maintain upper body strength. Cycling is a good aerobic exercise that’s helped me to build core and leg strength.

9. Find a friend

Exercise is way more fun when you have someone to talk to. It’s also a lot more fun when you can incorporate a little friendly competition with someone else who’s as interested in staying in shape as you are.

10. Don’t get discouraged

My nutritionist taught me to not be discouraged if I didn’t see immediate results.

You may not see the scales tip in your favor right away. I realized that I was in a marathon, not a sprint.

Cancer changed many aspects of my life. I learned early on that I was in control of many of those changes, to a degree. I hope what I’ve learned over the years can help others who are just starting down this road.

The information presented is solely for educational purposes, not as specific advice for the evaluation, management, or treatment of any condition.