Understanding Weight Loss Caused by Chemotherapy

Despite what you've heard, weight loss is not a given

Weight loss may seem like the silver lining of chemotherapy, but the truth is that not everyone on treatment loses weight. It's one of the false impressions we've gotten from TV and film: where the character with cancer almost always ends up looking emaciated and frail. That is not to say that weight loss doesn't occur; it is simply not a given.

Person standing on scale
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In the end, everyone responds differently to chemotherapy, and there are many factors that play a role in how treatment will affect your weight. Sure, there are some who will lose weight, but there are those who gain, as well.

Understanding your nutritional needs and the possible side effects of treatment are the first steps to ensuring you maintain your ideal weight during the course of chemotherapy.

Factors Contributing to Weight Loss

When people lose weight during cancer treatment, it is most often due to an inability to maintain good nutrition. Chemotherapy can sometimes cause nausea and a general loss of appetite, while vomiting and diarrhea can greatly impact your ability to retain nutrients from the foods you eat.

At times, foods can taste and smell very different – even foul – as a result of cancer treatment. For this reason, alone, many specialists recommend avoiding your favorite foods as any changes in taste or smell will be more profoundly perceived, creating an aversion to them even after treatment is complete.

Mouth sores can also be a side effect of chemotherapy. Having them on your gums, throat, tongue, or inner cheek can make eating certain foods extremely difficult, exacerbating the pain you may already be feeling. Spicy, salty, or sour foods are especially problematic.

Maintaining Weight During Chemotherapy

One of the mains health goals you should strive for during chemotherapy is to keep your weight stable. If you are overweight, now is not the time to start losing. You can, however, focus having a more healthy diet, which you can carry over post-treatment to reach your ideal weight.

If your healthcare provider feels you are up to it, work together to create an exercise plan to meet your fitness needs. Walking, yoga, and other forms of exercise are not only ideal ways to keep fit, but they can also help relieve stress, elevate your mood, and even reduce fatigue.

Working with a dietitian experienced in cancer therapy can be extremely beneficial. A professional trained in the nutritional needs of a person with cancer will be more able to formulate, monitor, and adjust your diet as you move through treatment. Most cancer centers have a nutritionist on staff or can refer to a certified professional in your area.

A Word From Verywell

It almost goes without saying that good nutrition is essential during chemotherapy. If your caloric intake is too low, it can lead to weight loss while lowering your ability to cope physically and mentally with your treatment.

Poor nutrition can also lead to a drop in your blood cell counts, resulting in anemia, neutropenia, or thrombocytopenia. This will not only make you feel tired and fatigued, but it can also lead to the discontinuation of therapy until such time as your levels are restored.

In addition to good nutrition, exercise of any sort can be beneficial if approached wisely and under the supervision of a medical professional. Even a little outdoor activity (such as gardening) can prevent the loss of lean muscle mass key to maintaining strength and mobility.

Overexertion, on the other hand, is not advised as it can not only wear you out but cause inflammation that can worsen any side effects you may be experiencing.

Good planning, a balanced diet, and a moderate approach to fitness are three things you need to ensure you meet your health goals during the course of chemotherapy. 

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3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. National Cancer Institute. Eating Hints: Before, during, and after Cancer Treatment

  3. Chaveli-lópez B, Bagán-sebastián JV. Treatment of oral mucositis due to chemotherapy. J Clin Exp Dent. 2016;8(2):e201-9. doi:10.4317/jced.52917