Weight loss: when to worry and what to do
Weight loss is common during treatment, and it can be muscle as well as fat. This affects strength, how well you tolerate treatment and resistance to infection. This section explains how to track weight and what to do.

01Short answer
02Simple explanation
Weigh yourself weekly.
Lost over 5%? Tell us.
Protein at every meal.
Movement protects muscle.
03Scientific explanation
ESPEN: nutritional risk in people with cancer should be checked regularly, and nutrition support should start early when weight loss is found.
ESPEN: enough energy and protein matter for preventing weight and muscle loss in people with cancer, and nutritional status should be assessed regularly.
NCI: practical eating tips exist for treatment side effects such as nausea, taste changes and mouth sores.
04What happens in the body?
How much protein?
General guidance suggests more than 1 g of protein per kg of body weight a day; your doctor and dietitian set your amount.

Nutrition support
If you cannot eat enough by mouth, tube or intravenous feeding can help for a while.

Dietitian
If you are losing weight, have no appetite or need a special diet, ask to see the hospital dietitian.
Food safety
Food-safety rules for neutropenia (see “Handwashing: the simplest protection” and “Eggs and dairy: safe choices”) apply at every stage.
05Nutrition: four steps
Assess, swap the risky, cook safely, eat regularly.







06Key points at a glance
| Topic | In brief |
|---|---|
How much protein? | General guidance suggests more than 1 g of protein per kg of body weight a day; your doctor and dietitian set your amount. |
Nutrition support | If you cannot eat enough by mouth, tube or intravenous feeding can help for a while. |
Dietitian | If you are losing weight, have no appetite or need a special diet, ask to see the hospital dietitian. |
Food safety | Food-safety rules for neutropenia (see “Handwashing: the simplest protection” and “Eggs and dairy: safe choices”) apply at every stage. |
07Key terms
- Cachexia
- Loss of muscle and weight caused by illness.
- Tube feeding
- Giving nutrition into the stomach through a tube.
- Dietitian
- A nutrition specialist.
- Protein
- A nutrient for repairing muscles and tissues.
- Neutropenia
- Low neutrophils.
08Key points
- Track your weight.
- Speak up early.
- Protein and movement.
- A diet is not a treatment.
- Talk to a dietitian.
09Frequently asked questions
Isn’t losing a little weight good?
During treatment weight loss is often muscle loss and causes weakness.
Is a feeding tube frightening?
It is temporary help; your team will explain the benefit.
Can a special diet cure leukemia?
No. Good nutrition helps you cope with treatment, but it does not cure.
10Questions for your doctor
Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.
Isn’t losing a little weight good?
Is a feeding tube frightening?
Can a special diet cure leukemia?
12Sources
- National Cancer Institute. Eating Hints: Before, During, and After Cancer Treatment
- ESPEN. ESPEN practical guideline: Clinical Nutrition in cancer (2021)
- Leukemia & Lymphoma Society. Food and Nutrition
- World Health Organization. Healthy diet fact sheet
- Harvard T.H. Chan School of Public Health — The Nutrition Source. Types of Fat
- British Dietetic Association. Fat: Food Fact Sheet
- British Dietetic Association. Omega-3: Food Fact Sheet
- MedlinePlus (U.S. National Library of Medicine). Dietary Fiber
- NHS. How to get more fibre into your diet
- Harvard T.H. Chan School of Public Health — The Nutrition Source. Fiber
How much protein?
Nutrition support