Obesity

Obesity means having more body fat than what's calculated to be healthy. Obesity increases the risk of diabetes, heart disease, stroke, arthritis, and some cancers. In people with obesity, losing even 5–10% of the total weight can delay or prevent some of these other conditions.^[1]

Obesity is defined as having a body mass index (BMI) of greater than or equal to 30 kilograms per meters squared (kg/m2; “meters” meaning a person’s height). More specifically, a person with:^[2]

• A BMI of 25 to 29.9 is “overweight”
• A BMI of 30 to 34.9 has “class I obesity”
• A BMI of 35 to 39.9 has “class II obesity”
• And a BMI of 40 or higher has “class III obesity”

While BMI is a generally useful measurement at the population level, because it only accounts for total body mass, individuals who are tall and/or muscular may have a BMI that qualifies as “obese”. As such, it’s useful to factor other measures like body fat percentage into an evaluation of whether someone has obesity.^[3]

The primary treatment for obesity in patients without other health conditions is lifestyle modifications (i.e., changes to diet and exercise); sometimes, weight loss medications are also used. If lifestyle modifications do not work after trying for a long time, or if the person has class II or III obesity with additional chronic conditions like heart disease or diabetes, then bariatric surgery may be considered.^[2]

Many dietary supplements and dietary ingredients have been studied for weight loss. In a recent meta-analysis of 67 randomized trials, the dietary ingredients chitosan, glucomannan, and conjugated linoleic acid were shown to help reduce weight by 1–1.9 kilograms. Other ingredients commonly studied for weight loss include green-tea-extract, green-coffee-extract, bitter orange, and Garcinia cambogia. Evidence about their effects is limited.^[4]

Diet is central to both the development and the management of obesity and the mainstay of dietary interventions for treating obesity involves calorie restriction. A commonly used approach includes limiting daily calorie intake to 1200–1500 kilocalories (calories adjusted to a person’s weight) for women and 1500–1800 kilocalories for men. Another approach is eating a diet with a 500–750 kilocalorie deficit. Many different types of diets have been used for weight loss; the diet that will be most beneficial over time will vary from person to person, and adherence to the diet is crucial.^[2]

Physical activity and behavioral therapies are important in the treatment of obesity. Increasing physical activity increases calories burned and works in tandem with calorie-restricting diets for obesity. Engaging in 200–300 minutes of physical activity per week is recommended for those with obesity. Behavioral therapy usually involves regular self-monitoring of food intake, physical activity, and changes to weight.^[2]

Obesity happens after a prolonged time of eating more calories than what is needed and used by the body. Extra calories are stored as fat. The factors that determine caloric need differ for each person. Factors that affect weight include genetic makeup, overeating, eating high-fat foods, and not being physically active.^[1]