The link between weight control and cancer treatment

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    Having extra weight is associated with an increased risk of cancer development. But during a cancer diagnosis, how does being overweight affect disease progression or the success of the selected treatment? The treatment itself very often affects body weight, so get informed on the latest research on this very important topic.

    What does it mean to have extra weight at the time of a cancer diagnosis?

    Having extra weight is generally associated with worsened outcomes following a cancer diagnosis. More and more research is pointing out that obesity negatively affects the delivery of conventional cancer therapies and reduces their efficacy.

    Having extra weight is also associated with more side-effects resulting from common cancer treatments.

    Positive effects of controlling weight after being diagnosed with cancer

    Overweight patients facing cancer can decrease the chance of cancer metastasis and improve prognosis of the disease by taking steps to reach a healthy weight.

    Recent studies have shown that overweight cancer patients who lost weight reported to have a significantly better quality of life. One particular study examined patients with endometrial cancer who participated in a lifestyle intervention program for 6 months. The study showed that those patients who achieved a significant weight loss had positive changes in their self-efficacy and overall quality of life. Other studies have shown improvements in physical fitness, sleep patterns and fatigue levels. In one particular study, overweight and obese cancer patients who participated in a 15-week healthy living program implemented through their oncology clinic, had achieved an average weight loss of 4.6 kg. A control group from the same clinic with people who did not participate in the healthy living program had gained 0.2 kg over the same period of time. The healthy living program focused on reducing calories by 500 to 1000 per day and engaging in 150 minutes of moderate to intense exercise per week. The people who participated in the program had an improved physical fitness at the end of the program and also reported improved sleep patterns and improvements in their fatigue levels.

    Other studies suggest that maintaining or increasing physical activity and controlling weight after a cancer diagnosis may improve the psychosocial well-being in breast cancer patients. In a study of 1348 breast cancer patients, weight loss and / or maintenance was associated with lower fatigue, lower depression, anxiety and stress, and higher physical, social, emotional and functional well-being.

    Also important to note is the fact that overweight cancer patients who lose weight generally maintain a better health status. They have better blood pressure, and less risk factors for developing chronic diseases such as heart disease and diabetes.

    Causes of weight gain during a cancer treatment

    Many people often gain weight after their treatments, especially patients with hormone related cancers like prostate and breast cancer. Women whose treatment involves inducing menopause are most likely to experience weight gain.

    There are many factors that might contribute to weight gain with cancer treatments:

    • Fatigue is very common among people having chemo and radiation, and can lead to less physical activity, which means fewer calories burned.

    • Nausea is another common side effect of these treatments, and many people eat frequent snacks to help deal with the nausea.

    • Other people eat more when they feel stressed, and having cancer is by itself a very stressful situation that might lead to overeating.

    • Hormone changes or medications may cause people to feel hungry or retain water.

    Prevent weight gain to avoid cancer recurrence

    According to the American Cancer Society, gaining weight after being diagnosed can give patients a higher risk of the cancer returning. In fact, a recent study showed that men, who gained about 5 pounds (2.2 kg) in the years after surgery for prostate cancer, had higher rates of recurrence than those with stable weight. For breast cancer, studies also suggest that weight gain after treatment can increase recurrence risk and decrease survival.

    So what can you do if you have cancer and are worried about your extra weight?

    • Assess your weight with your cancer care team.

    • Discuss the effect your weight has on your overall health with your medical team and with a dietitian (preferably one that is specialized in cancer issues).

    • Ask for help in achieving a healthier weight or in helping you to prevent weight gain during treatment.

    • Follow a well-balanced diet and aim to achieve long-term improvements in your dietary habits.

    • Add at least 150 minutes of moderate intensity activities per week. Stay active to help combat fatigue and control side effects like constipation and nausea.



    1. American Society of Clinical Oncology Position Statement on Obesity and Cancer, Journal of Clinical Oncology; November 1, 2014, Volume 32, no.32, pp3568-3574, Jennifer A. Ligibel, Catherine M. Alfano et al.

    2. American Institute for Cancer Research:, accessed 30/10/2014

    3. Journal of Clinical Oncology November, 2009 doi:10.1200/JCO.2009.23.1274 Meta-Analysis of Breast Cancer Outcomes in Adjuvant Trials of Aromatase Inhibitors Versus Tamoxifen; Mitch Dowsett, Jack Cuzick et al.

    4. McCarroll, M. L., et al. "Self-efficacy, quality of life, and weight loss in overweight/obese endometrial cancer survivors (SUCCEED): a randomized controlled trial." Gynecologic oncology 132.2 (2014): 397-402.

    5. Yung RL et al. A randomized trial of a clinic-based weight loss intervention in cancer survivors. Accessed at: on 17/2/2016

    6. Phillips, Siobhan M., and Edward McAuley. "Associations between self-reported post-diagnosis physical activity changes, body weight changes, and psychosocial well-being in breast cancer survivors." Supportive Care in Cancer 23.1 (2015): 159-167. 7.


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