To function properly, the body needs energy (or fuel). This energy comes from the food we eat. When we eat more than the body needs, the body stores the leftover energy as fat. This is useful, as the stored fat can be used as a reserve when more energy is needed (for example during exercise, or when you suddenly have less access to food).
It is healthy for the body to have some fat stored. However, when the body stores too much fat you become overweight or obese. This can cause a wide variety of health problems such as heart problems, stroke and diabetes. For more information on strokes, heart attacks and diabetes, please read: Strokes, heart attacks, impaired glucose metabolism and diabetes.
The unit of measurement that helps determine if you have a healthy weight is the Body Mass Index (BMI).
To measure your BMI, weigh yourself on a scale. It is best to weigh yourself in the morning, before breakfast and without any clothes on. Also measure your height without shoes on. Then make the following calculation:
Height (in metres) x height ( in metres) = height squared
Weight (in kilograms) / height squared = BMI
For adults (18 years or older) a healthy BMI usually ranges between 18.5 and 25. A BMI below 18.5 or above 25 increases the risk of health problems. When the BMI is between 25 and 30, we consider someone to be overweight. When the BMI is above 30, we speak about obesity. However, there are exceptions. For example, when you are pregnant, breastfeed or have a lot of muscle mass, a BMI above 25 is not necessarily unhealthy.
There are a number of things anyone can do to get to a healthier weight or to lower the risk of being overweight and obese, such as adopting or maintaining a healthy lifestyle. For more information on taking up a healthier lifestyle, please read: Health promotion.
Am I at higher risk of being overweight or obese?
Anyone, including people who have never had cancer treatment, may become overweight or obese. However, there are some medical conditions and treatments that may increase the risk of becoming overweight or obese later in life.
The following medical condition can increase the risk of becoming overweight or obese:
A tumour near or within the hypothalamic-pituitary (HP) axis. Damage to the HP axis can increase the risk of becoming overweight and obese.
The following treatments can increase the risk of becoming overweight and obesity:
Radiotherapy to the HP axis or an area including the HP axis
Surgery involving the HP axis
You can find out if you had any of these medical conditions or treatments by looking at your treatment summary. If you do not have a treatment summary or if you have any questions, do contact your treating hospital.
If you are overweight or obese, it does not always mean that this is caused by cancer or its treatment. Being overweight or obese is very common in modern western society. Being overweight or obese may have other causes such as a sedentary lifestyle and unhealthy diet. It can also be secondary to endocrinological, familial, congenital conditions and several drugs (e.g. steroids, antidepressants).
I am at higher risk of being overweight or obese. What tests should I have and when?
If you are at higher risk of becoming overweight and obese, it is advised to:
Have your height, weight and BMI measured at least every 2 years. You can do it as well at home. If you see your general practitioner or follow-up care specialist more often, it is best to measure your height, weight and BMI at each visit.
What happens if I am overweight or obese?
If you are overweight or obese, your general practitioner or follow-up care specialist will probably refer you to a specialist. Depending on the cause of overweight or obesity, you may be referred to a:
Dietician (specialist who advise on eating habits and lifestyle)
Endocrinologist (physician who specialises in hormones and metabolism)
The specialist may discuss different options with you such as improving your diet and lifestyle.
You may also be advised to have your blood pressure, blood glucose (sugar), blood lipids (eg. cholesterol: a fatty substance in the blood) measured regularly. When you are overweight or obese, it is important to be aware of other factors that may influence your risk of (future) problems with the heart or blood vessels. For more information on high blood pressure, diabetes or dyslipidaemia (abnormal blood lipid levels) please read: Hypertension, impaired glucose metabolism and diabetes, dyslipidaemia.
What else can I do?
Knowing that you may be at increased risk of being overweight and obese can be difficult. Talking to friends and family can be helpful as well as specialist counselling and/or contact with support groups, such as patient organisations. For more information on taking care of your mental health, please read: Mental health problems.
To lower your risk of overweight and obesity, adopting or maintaining a healthy lifestyle is extremely important. In particular, it is important to limit the intake of fatty foods. Taking care of your mental health may be beneficial; even small changes to your lifestyle can have a positive impact on both your physical and mental health. For more information on taking up a healthier lifestyle, please read: Health promotion.
It is also important that you monitor your weight regularly at home.
It is important that you are aware of the possibility of becoming overweight or obese and that you know the symptoms and signs. If you have any further questions or if the information in this brochure worries you, please contact your general practitioner or follow-up care specialist.
Where can I find more information?
You may find more information about overweight and obesity online. However, it is important to be aware that this information is not always up to date or accurate.
While the PanCare PLAIN information group strives to provide accurate and complete information that is up-to-date as of the date of publication, you can check with your general practitioner or follow-up care specialist if this summary reflects the most up-to-date information available and whether it is relevant for you.
Please do not rely solely on this information. It is best to also seek the advice of a qualified medical practitioner if you have questions regarding a specific medical condition, disease, diagnosis or symptom.
No warranty or representation, expressed or implied, is made concerning the accuracy, reliability, completeness, relevance, or timeliness of this information. PanCare has produced the English version and PanCare is not responsible for the translated versions of this summary.
 van Kalsbeek, R. et al. (2021) European PANCAREFOLLOWUP recommendations for surveillance of late effects of childhood, adolescent, and Young Adult Cancer, European journal of cancer. Available at: https://www.ejcancer.com/article/S0959-8049(21)00368-3/fulltext.