Cancer and Weight Management

Content authored by Amanda Mondini, RD, LD, at TCSC

Weight is an important metric that can be indicative of our overall health. Losing weight is typical for cancer patients due to side effects associated with both chemotherapy and radiation therapy. However, you may not know, that during active treatment, it is very common for doctors and registered dietitians to set a goal of weight maintenance. This is a goal regardless of the patients’ overweight or obese status because weight constancy supports the body and data shows it improves patient outcomes.

For example, an early-stage breast cancer study conducted in 2017 concluded that large weight losses of greater than 10% of a patient’s body weight were associated with worse survival (1). If you are on active treatment and/or are struggling to maintain weight, please visit our blog posts Nutrition Tips for Chemotherapy Patients and Nutrition Tips for Radiation Therapy Patients for guidance on side effect management and weight maintenance.

However, if you are on maintenance treatment, a cancer survivor, and/or your doctor has given you the green light to pursue weight loss, keep on reading.

Understand Your BMI

First, let’s discuss one of the ways to measure body fatness that can give you some insight into the appropriateness of your weight in relation to your height. This is your body mass index or BMI. BMI “is the most commonly used marker of adiposity [the condition of having too much fat in the body] in epidemiological studies owing to its simplicity of assessment, low costs, and high precision and accuracy” (2). It is important to note that BMI “does not differentiate between lean and adipose [fat] tissue mass, the relative proportions of which vary between people, and with age, sex, and ethnicity. Unusually muscular and lean people (such as manual workers and power athletes) may have a relatively high BMI, even if they have relatively little body fat” (2). Though BMI is not a perfect measurement, “it has been shown to be reliably linked to body fatness” (2). Calculate and interpret your BMI here!

Weightloss and Improved Health

Now, if you want to understand why weight loss is recommended for those with high levels of body fatness, check out the 2018 World Cancer Research Fund and American Institute for Cancer Research’s “Body fatness and weight gain and the risk of cancer” section of the 2018 Continuous Update Project Expert Report. There is evidence that “greater adult body fatness is a convincing cause of cancers of the esophagus (adenocarcinoma), pancreas, liver, colorectum, breast (postmenopause), endometrium, and kidney.” Not only this, but people who are obese, compared to those at a healthy weight, are at increased risk for coronary heart disease, stroke, type 2 diabetes, sleep apnea, and breathing problems, as well as body pain and difficulty with physical functioning (3).

Knowing that greater body fatness and overweight/obesity may contribute to developing these chronic issues could prompt you to pursue weight loss, but where do you begin? This is a struggle for many people. I’ve included 5 tips below to help guide you as you pursue healthy weight loss and overall wellness.

5 Healthy Weight Loss Tips

  1. Aim to lose 5-10% of your current weight. Though this may not sound like much, it is important to remember that weight loss that is slow and controlled is more sustainable over a long period of time. Losing just 5-10% of your current weight can have noticeable benefits, such as improvements in blood sugar, cholesterol, and blood pressure.
  2. Determine your estimated calorie and protein needs for weight loss, factoring in any current or planned physical activity. To get the most accurate estimates, I recommend seeing a Registered Dietitian (RD) that understands your specific medical history. In general, however, 2,000 calories per day is used as a guide for nutrition advice. This is highly variable based on age, sex, height, weight, physical activity level, and medical conditions.
  3. Count calories if it helps. Please hear me loud and clear- do NOT count calories if you think that it will become an obsession for you. I typically recommend that my weight management patients count calories when they start seeing me just to get an idea of how many calories certain foods and beverages contain. It will surprise you! If you decide to count calories, I recommend using an app like MyFitnessPal or MyPlate Calorie Counter to track your intake.
  4. Increase physical activity. Per the Centers for Disease Control (CDC), “adults need 150 minutes of physical activity each week, including aerobic activity and muscle-strengthening activity” (4). Broken down into chunks, that could be 30 minutes per day for 5 days each week. If this sounds overwhelming, no worries. Any increase in physical activity is a win- whether it’s dancing in the living room or gardening outside.
  5. Set goals beyond just weight loss. We are more than a number on a scale. Your weight does not equal your worth! Many of my weight management patients set goals like “I will be able to lower my blood sugar with fewer medications” or “I will be able to walk to get the mail without stopping to catch my breath”.

Weight management plays an important part in our health. Understanding the goals during cancer treatment is important. If you are beyond the active treatment phase of your journey, losing excess weight, when done healthily, will further improve your quality of life.


  1. Elizabeth M. Cespedes Feliciano, Candyce H. Kroenke, Patrick T. Bradshaw, Wendy Y. Chen, Carla M. Prado, Erin K. Weltzien, Adrienne L. Castillo, Bette J. Caan; Postdiagnosis Weight Change and Survival Following a Diagnosis of Early-Stage Breast Cancer. Cancer Epidemiol Biomarkers Prev 1 January 2017; 26 (1): 44–50.
  2. World Cancer Research Fund/American Institute for Cancer Research, Continuous Update Project Expert Report 2018. Body fatness and weight gain and the risk of cancer.
  3. “The Health Effects of Overweight and Obesity.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 17 Sept. 2020,
  4. “How Much Physical Activity Do Adults Need?” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 7 Oct. 2020,

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