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Weight Gain and Obesity in Childhood Cancer Patients

child getting height measured by a clinician

Weight gain can be a side effect of cancer treatment. 

It is best to work with your care team to make a plan to prevent weight gain at the start of treatment. That’s because too much weight gain early in treatment can be hard to reverse. This can have health effects during childhood and into adulthood. 

dietitian can help you learn about preventing and managing weight gain.  

Can cancer treatment cause weight gain in children?

Some treatments that can cause weight gain include:

  • Chemotherapy, which can cause fatigue and inactivity
  • Steroids, such as prednisone and dexamethasone, can increase appetite 
  • Radiation treatments directed at the brain 

Some treatments can also cause kids to retain water. This makes them gain weight and feel puffy. Other treatments can increase appetite. Kids feel hungry and eat more calories than their bodies need. 

Treatment and cancer itself can make kids more tired and less active. And that’s when weight gain happens. If it becomes a problem, talk to your health care team. 

Understand body mass index (BMI)

Body mass index (BMI) is one way to measure excess weight. It also takes height into account. The higher the BMI, the higher risk for health problems related to overweight and obesity. 

Overweight and obesity are defined as abnormal or excessive fat that is a health risk. 

  • Overweight
    • For children and teens ages 2-18 -- BMI at or above the 85th percentile or higher. 
    • For adults – BMI of 25 or higher 
  • Obese 
    • For children and teens ages 2-18 -- BMI at or above the 95th percentile or higher. 
    • For adults – BMI of 30 or higher.

Calculate your BMI

Starting at age 2, be sure your health care team is tracking your child’s BMI on the Centers for Disease Control and Prevention growth charts. This way, you’ll be able to focus on ways to address weight gain if your child’s BMI starts to rise. Just remember that the BMI number doesn’t tell the whole story. And it’s not the only way to measure health risks that relate to weight gain.

Physical issues with weight gain and obesity

At first, it may seem like a few unhealthy habits in the short term isn’t cause for concern. But treatment for some types of childhood cancer can go on for a few years. And once those unhealthy habits take hold, they’re likely to follow kids into their adult lives.

If weight gain continues, it can lead to more health issues. For example, one study measured the risk of heart disease in kids with obesity, ages 5 to 10. The study report noted that among these kids, 6 of 10 were already at risk for heart disease. 

Some patients are at risk for heart problems later in life because of their cancer treatment. Excess weight gain may make these problems worse.

Fatigue is another common challenge of both cancer and treatment. Kids may feel too tired to be active. Unlike “normal fatigue,” rest and sleep aren’t always enough to relieve it. So kids in cancer treatment may get tired after less activity than other kids. 

Emotional issues with weight gain and obesity

Kids going through cancer treatment may already have worry, stress, and fear. Concerns about weight gain and obesity can add to their emotional load. 

Weight gain can cause a distorted body image. As a result, kids may try strange diets, skip meals, or avoid whole food groups. Sometimes they can develop eating disorders. This can happen when they try to control weight in ways that aren’t healthy. 

Your health care team can help address these emotional issues. Some kids may benefit from counseling. 

Social issues with weight gain and obesity

The social stigma of being overweight or obese is just as real as the physical and emotional issues. As early as age 6, kids can begin to have negative thoughts about those who are overweight. They may even believe people who are overweight are also less likeable. 

Since much of social development happens during childhood, weight gain can cause challenges for kids. Those who have weight gain or obesity can be more likely to:

  • Have more body shame or lower self-esteem 
  • Lack self-confidence, which can cause poor school performance
  • Be told by others (including adults) that being overweight is their fault
  • Be the target of bullying and name-calling
  • Lose friends they once had or have trouble making new ones
  • Withdraw, feel lonely, and develop depression over time

Managing weight gain and obesity during cancer: Tips for families

Your health care team can help you find strategies that go along with your child’s stage of development. Here are some general tips:

  • Move away from the idea of food as a reward or treat: Making food a reward can lead to overeating foods high in sugar, fat, and empty calories (no nutrition). It can also train kids to reward themselves with food, even when they’re not hungry. Work with your child’s health care team to find other ideas for rewards—quality time with you is a great place to start.

Be sure grandparents and other family caregivers understand that food is fuel for health, not a reward. They need to understand and agree with the reasons for these changes.

  • Be aware of emotional eating. It’s natural for some people, including kids, to seek comfort in food during stressful times. The ups and downs of cancer treatment can also cause changes in eating habits and preferences. 
  • Aim for at least 60 minutes of moderate-to-vigorous activity for your child each day. Fatigue is a side effect of both cancer and its treatment. But staying active can give kids more energy and help them feel better. It’s usually safe to exercise during and after cancer treatment. Just ask your child’s health care team first. 
  • Take time to find out what your child likes and is able to do. It’s easier for kids to stick with something they enjoy doing. Their preferences will change over time.
  • Be aware of screen time. Children with special health care needs tend to be less active, watching more TV and playing more video games than other kids. These habits increase the risk for obesity. The American Academy of Pediatrics recommends limiting screen time to 2 hours or fewer each day for kids aged 2 years and older. And no screen time for babies and kids up to 2 years. 
  • Make healthy habits a family affair. Healthy habits are a good idea for everyone. Encourage everyone in the family to eat healthy and move more. Your child is more likely to make changes if others are doing so.

Key points

  • Weight gain during cancer treatment can have health effects during childhood and into adulthood. 
  • Body mass index (BMI) is one way to measure excess weight that also takes height into account.
  • Weight gain is a common side effect of chemotherapy, steroids, and radiation directed at the brain.
  • Fatigue is a common side effect of both cancer and its treatment. But staying active can give kids more energy and help them feel better. 
  • The social stigma of being overweight or obese can affect a child’s confidence, self-esteem, and social development.
  • Avoid treating food as a reward, aim for 60 minutes of activity for your child each day, and be aware of screen time.
  • Make healthy habits a family affair.

Reviewed: June 2021