Weight and muscle changes

Weight and muscle changes can be a side effect of hormone therapy for prostate cancer that lowers sex hormone (testosterone) levels.

Aim of hormone treatment

Sex hormones and hot flushes

Some cancer treatments can lower the levels of sex hormones in the body. The sex hormones are oestrogen and progesterone in women, and testosterone in men. The cancer treatments include hormone treatments for prostate cancer.

Prostate cancer needs testosterone to grow. Hormonal treatments aim to:

• stop the testicles from making testosterone
• stop testosterone reaching cancer cells

How do sex hormones affect weight and muscle?

As we get older we lose muscle strength. Hormone treatment which lowers testosterone levels can also cause loss of muscle bulk in men. It can lead to:

• loss of muscle mass (sarcopenia)
• loss of muscle strength (dynapenia)

Hormone treatment can also cause you to put on weight (fat). This is usually around your waist. Hormone treatment can also make you feel tired and this can make you less active. This can then make the weight gain worse, as you might be less active. 

Exercise, muscle mass and weight gain

Changing your diet and being more physically active may help you to maintain your normal weight.

Physical activity can help to maintain muscle strength, but it needs to be a combination of aerobic and resistance exercise.

Aerobic exercise is any exercise that makes your heart and lungs work faster to provide more oxygen to the muscles for example walking or gardening.

Resistance training includes weight training and swimming. You have to use your muscles to push against the weights or water, which helps to strengthen them.

Physical activity also helps to control your weight. You don’t have to go to the gym, you can build it into your life. For example, you could get off the bus the stop before you need to, do some gardening or join a walking group. Some hospitals organise exercise sections for cancer patients. Ask your specialist nurse if this is available. 

You should aim to be physically active for 30 minutes 5 days a week. Your doctor may check your cholesterol and heart health before you start an exercise plan. This is important if you have conditions such as diabetes or you are overweight.

Hormone treatment may lower your bone density, increasing the risk of fractures. Talk to your doctor if this could be a problem for you.

Eating a balanced healthy diet can help you to maintain a healthy weight. It can also help you lose or put it on if you need to.