How is weight gain related to cancer treatment?

As your doctor helps you fight your disease, we at (un) cancer aim to help ease your journey through the treatment and recovery stages till you get back to your best life.


Maintaining proper body weight during cancer treatment can be difficult. Because during this time some people lose weight, some people gain weight. There is no harm if a slight increase in weight during the treatment of cancer, but if the weight gain is too much, one needs to be careful.

Weight gain and cancer

Weight gain is the most common side effect in some cancers and in some treatments. For example, more than half of people with breast cancer gain weight during the treatment. Studies show that excess weight gain during treatment is directly related to the poor chance of recovery. Also, being overweight before starting treatment can increase the risk of further complications during recovery. There is a risk of having side effects like high blood pressure, diabetes, and heart problems.

Why do cancer treatments can cause weight gain?

Cancer treatments like chemotherapy, steroid treatment, and hormone treatments can lead to weight gain in different ways.


Chemotherapy is a type of cancer treatment that uses one or more anti-cancer to destroy cancer cells. This can lead to weight gain by:

1 - Causing the body to hold on to excess fluid, called edema.
2 - Causing fatigue, making it harder to exercise.
3 - Increasing nausea that improves by eating more food.
4 - Triggering intense food cravings.
5 - Lowering your metabolism rate.
6 - Causing menopause.

Steroid medications

Steroids can reduce symptoms of inflammation, such as swelling and pain. They can treat nausea and they can be used as a treatment for cancer as they kill cancer cells and shrink tumors as part of chemotherapy.

The most common side effect of steroids is weight gain. They can lead to weight gain by:

1 - Increasing the appetite.
2 - Decreasing muscle mass is called wasting.
3 - Increasing fat tissue in the abdomen, neck, face, or other areas.

Hormonal therapy

Certain cancers including breast, prostate, testicular, and uterine required hormonal therapy treatment for recovery. This therapy can decrease the number of certain hormones, such as estrogen, progesterone, or testosterone. This can increase fat, decrease muscle, and make it harder to burn calories.

It can be hard or stressful for some people to talk about weight gain with their doctor. Many of them feel ashamed about their weight gain during this phase. Some of them may experience discrimination because of their weight. But weight gain is just a side effect of cancer treatment and it's not a permanent condition. It is important to talk to your doctor about this and get medical consultation as soon as possible.