Obesity
(Overweight · Unhealthy Weight)
In this condition factsheet:
The Facts on Obesity
Obesity is a leading cause of preventable illness and death in North America. It is defined by having a body mass index (BMI) of 30 or greater. In recent years, the number of overweight people in industrialized countries has increased significantly, so much so that the World Health Organization (WHO) has called obesity an epidemic. In Canada, self-reported data shows that approximately 27% of Canadian adults are obese, and another 36% are classified as being overweight. People who are obese are at a much higher risk for serious medical conditions such as high blood pressure, heart attack, stroke, diabetes, gallbladder disease, and different cancers than people who have a healthy weight.
Causes of Obesity
Obesity occurs when your body consumes more calories than it burns. In the past, many people thought that obesity was simply caused by overeating and under-exercising, resulting from a lack of will power and self-control. Although these are significant contributing factors, doctors recognize that obesity is a complex medical problem that involves genetic, environmental, behavioural, and social factors. All these factors play a role in determining a person's weight.
Recent research shows that in some cases, certain genetic factors may cause the changes in appetite and fat metabolism that lead to obesity. For a person who is genetically prone to weight gain (e.g., has a lower metabolism) and who leads an inactive and unhealthy lifestyle, the risk of becoming obese is high.
Although a person's genetic makeup may contribute to obesity, it's not the primary cause. Environmental and behavioural factors have a greater influence – consuming excess calories from high-fat foods and doing little or no daily physical activity over the long run will lead to weight gain. Additionally, not getting enough sleep and certain medications may cause weight gain leading to obesity. Childhood obesity that persists beyond early childhood can make weight loss in adulthood more difficult. Around 15% of women permanently gain 20 or more pounds with each of their pregnancies.
Certain medical conditions such as binge eating disorder (BED), Cushing’s disease, and polycystic ovary syndrome can also lead to weight gain and obesity. BED is an eating disorder where a person has recurrent episodes of binge eating. During these episodes, the individual eats a large amount of food quickly and feels a lack of control over this eating.
Psychological factors may also foster obesity. Low self-esteem, guilt, emotional stress, or trauma can lead to overeating as a means to cope with the problem. Adverse childhood events or abuse during childhood can increase the risk for obesity.
Symptoms and Complications of Obesity
The health risks associated with obesity include:
- breathing disorders (e.g., sleep apnea, chronic obstructive pulmonary disease)
- certain types of cancers (e.g., prostate and bowel cancer in men, breast and uterine cancer in women)
- coronary artery (heart) disease
- depression
- diabetes
- gallbladder or liver disease
- gastroesophageal reflux disease (GERD)
- high blood pressure
- high cholesterol
- joint disease (e.g., osteoarthritis)
- stroke
- reproductive system disorders, including decreased fertility
People who are obese may have the symptoms of the medical conditions mentioned above. High blood pressure, high cholesterol levels, breathing problems, and joint pain (in the knees or lower back) are common.
The more obese a person is, the more likely they are to have medical problems related to obesity.
Aside from the medical complications, obesity is also linked to psychosocial problems such as low self-esteem, discrimination, difficulty finding employment, and reduced quality of life.
