Obesity is a disease involving an excessive amount of body fat, occurring due to a number of factors. The first line of diagnosis is the measurement of body mass index (BMI). BMI is a person’s weight relative to their height. A BMI of 30.0 or higher is considered obesity, and there are 3 categories: Class 1: BMI of 30 to < 35; Class 2: BMI of 35 to < 40; Class 3: BMI of 40 or higher (extreme” or “severe” obesity). Other diagnostic methods used are waist circumference measurements and blood tests. The main causes of obesity are: 1) Excessive calorie intake - eating a greater amount of calories than is expended, usually from fried & fatty foods, processed meats, dairy products, sugary baked goods, and high-carbohydrate foods, 2) Sedentary lifestyle & irregular physical activity - therefore not burning enough calories, 3) Inadequate sleep - sleep deprivation may lead to obesity because it can lead to hormonal changes that increase appetite, 4) Endocrine disruptors - e.g. liquid fructose in beverages may alter lipid energy metabolism and lead to fatty liver and metabolic syndrome, 5) Medications - certain medications can lead to weight gain e.g. anticonvulsants and mood stabilizers, diabetes medications, glucocorticoids used to treat rheumatoid arthritis, antidepressants, 6) Obesity gene - the fat-mass and obesity-associated gene (FTO) increases the risk of obesity, and genetics may also affect how the body stores and distributes fat, 7) Medical conditions e.g. Prader-Willi syndrome, Cushing syndrome, and arthritis. Obesity can occur at any age. Other risk factors include pregnancy (weight gain is common during pregnancy), smoking, stress and gut microbiome. Untreated obesity can lead to serious health conditions including heart disease, stroke, type 2 diabetes, sleep apnea, osteoarthritis, infertility and irregular periods in women, certain cancers e.g., cancer of the uterus, pancreas, prostate. Obesity can also affect quality of life in the form of depression, shame and guilt, low confidence and self-esteem, and social isolation. Treatment may require a combination of reducing calorie intake; practicing healthier eating habits; exercise regularly; seek help from counselling to assist in behavior modification; prescription weight-loss medication e.g., Orlistat; endoscopic procedures for weight loss; weight-loss surgery e.g. gastric bypass surgery.