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Bodyweight & Cancer

Christina L. DiSegna, MS, RD, CSO, CNSC, LDN
Senior Clinical Dietitian
Brigham and Women’s Hospital

Maintaining a healthy weight has been shown to be an important factor in many aspects of health, including overall cancer survivorship and quality of life.

Body mass index (BMI) is used to determine if one is at a healthy weight for their height. BMI is calculated as weight in kilograms divided by height in meters squared. Overweight is defined as BMI > 25 kg/m2 and obesity as BMI > 30 kg/m2. Normal BMI range is 18.5-24.9 kg/m2. Energy balance includes both diet and physical activity; imbalances in energy consumed and energy expended can lead to a positive energy balance and thus an increase in body weight.

Recent research has revealed that overweight/obesity, physical inactivity, and poor diet quality have been shown to decrease overall and cancer-specific survival. Additionally, obesity has been linked with worse outcomes in areas such as quality of life, cancer recurrence, and disease progression. This research also suggests that weight maintenance and avoiding weight gain during treatment as well as intentional weight loss following treatment may have important health-related benefits. Studies have shown that lifestyle interventions involving weight, dietary changes, and increased physical activity improve quality of life, minimize disease and treatment-related side effects, and may improve response to treatment. Additionally, some preliminary research is suggestive of improved prognosis in early-stage cancer diagnosis with lifestyle changes.

Several studies have shown that weight loss of as little as 5-10% of current weight is associated with improved quality of life and physical functioning in cancer survivors. This weight loss also leads to decreased risk for cancer recurrence or development of a secondary cancer. Additionally, as overweight and obesity are also linked to increased risk of many chronic illnesses, weight loss can also decrease risk for developing those illnesses. Research has suggested that for some, intentional weight loss of 1-2 pounds per week during treatment is safe and feasible, provided it is closely monitored by the oncology team and it does not interfere with treatment. For others, it may be more appropriate to postpone weight loss efforts until active treatment is completed. Even if not achieving weight loss, changes in diet and physical activity can lead to decreased fatigue, increased quality of life, and may improve survival. Therefore, small, sustainable changes to overall diet and exercise, as well as improvements in weight may lead to important positive outcomes in cancer survivors.


  • Maintain weight within a healthy BMI range (18.5-24.9 kg/m2)
  • If BMI is greater than 25 kg/m2, even modest weight loss of 5-10% of current weight will improve overall health.
  • Modest weight loss of 1-2 pounds per week may be appropriate during treatment – discuss with your oncologist and dietitian
  • Avoid excess weight gain in adulthood, even if within a normal BMI range
  • Fill your plate with colorful fruits and vegetables. These contain phytonutrients, fiber, vitamins, and minerals that can help support a healthy immune system and protect against developing cancer. Aim for half of your plate to contain fruits and vegetables
  • Choose lean protein sources at meals, including poultry, fish, eggs, low-fat dairy, beans, and nuts. Protein foods provide fuel for muscles and help improve satiety. Limit red meat and avoid processed meats
  • Choose whole grains such as whole-wheat bread or pasta, brown rice, and quinoa at meals rather than refined (white) grains. Whole grains contain fiber, vitamins, and minerals that are missing in refined grains
  • Include healthy fats like olive oil or nuts to help promote satiety
  • Avoid concentrated sweets and sugar-sweetened beverages. These foods are calorie dense without much nutritional benefit and can lead to weight gain or hinder weight loss
  • Drink water! Replace sugar-sweetened beverages with water
  • Be physically active. Aim for at least 30 minutes of physical activity per day. Not only will this help with weight management, it can improve your overall physical and mental health
  • Meet with a registered dietitian. A dietitian will provide personalized advice and support for weight maintenance and a healthy diet throughout cancer treatment.
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  2. Ligibel J, Meyerhardt J. The roles of diet, physical activity and body weight in cancer survivors. Up To Date. Accessed 19 June 2018.
  3. Thomson C, Vargas A. Chapter 10: Nutrition and Cancer Survivorship. Oncology Nutrition for Clinical Practice. 2013. p87-96