Maintaining a healthy weight throughout life can cut the risk of 13 different cancers.
Excess weight is on track to become the second leading preventable cause of cancer, after tobacco.
It’s estimated that by 2042, the number of cancer cases due to excess weight will nearly triple—from 7,200 to 21,200. Currently, more than one in two Canadian adults are not at a healthy body weight, putting them at risk for serious health problems like heart disease, diabetes, stroke and cancer.
A healthy weight is one that contributes to your overall health, well-being and quality of life. It's different for each individual. Your weight is not simply a result of what you eat or how active you are. Genetics, health conditions, stress, sleep quality and other factors can also influence your weight.
Body Mass Index (BMI) and waist circumference can be used as indicators of health risk related to under and overweight.
The most widely used tool to estimate if a person is in a healthy weight range is the body mass index (BMI). In general, the higher the number, the more body fat a person may have and the greater the risk for health problems.
- A person with a BMI of 18.5 to 24.9 kg/m2 is considered to be in a healthy weight range.
- BMI isn’t perfect—it doesn’t take into account body shape, composition (distribution of fat and muscle) or fitness levels.
- Weight is only one indicator of health risk. Other factors include lifestyle habits, fitness level and whether you have any health conditions.
If you are concerned about your weight, speak with your health care provider. You can also call 8-1-1 for health and nutrition advice.
Your waist circumference can be an important measure of health. It is an indirect indicator of intra-abdominal fat tissue, often called visceral fat. Visceral fat is a type of fat that wraps around internal organs like your liver, kidneys and intestines.
To measure your waist circumference, place a tape measure around your body at the top of your hip bone (usually at the level of your belly button). You are at increased risk for health problems if you are:
- A man with a waist circumference greater than 102 cm (40 in.)
- A woman with a waist circumference greater than 88 cm (35 in.)
Even at a healthy weight, if you have a large waist circumference, you may be at risk for serious health problems.
Carrying excess weight, especially around the waist, can increase your risk of developing at least 13 types of cancers, including cancers of the esophagus, breast, liver, gallbladder, kidney, colon and rectum, thyroid and others.
Scientists are still studying the link between excess weight and cancer risk, but have proposed the following reasons:
- Excess weight and body fat, especially around the middle, can make it harder for your body to use a hormone called insulin, which controls your blood sugar levels. This encourages the body to produce more insulin, and that can cause cells to multiply more quickly.
- Excess body fat also produces more of the hormone estrogen. Estrogen can help some cancers, like breast cancer, develop and grow.
- The buildup of fat in the body can trigger inflammation, which can promote the growth of cancer by encouraging cancer cells to divide. This might explain why having excess weight increases the risk of cancers like colon, rectum, liver, esophagus, kidney and others.
- In 2015, 7,200 new cancer cases in Canada were due to excess weight.
- If the trend continues, the number of new cancer cases due to excess weight will triple from 7,200 to 21,200 in 2042. It’s expected to become the second most common cause of cancer behind smoking.
- If more Canadians were at a healthy weight, about 110,600 cancer cases could be prevented by 2042.
- Eating a healthy diet, being at a healthy weight and keeping physically active can prevent up to one-third of the most common cancers, and up to one-half of all colorectal cancers.