Short answers, pulled from the story.
Obesity is a medical condition in which excess body fat accumulates enough to harm health. It is most commonly defined by a body mass index over 30, calculated as a person's weight divided by the square of their height. In scholarly circles the preferred measure is body fat percentage, with obesity indicated above 32 percent for women and 25 percent for men.
In 2022, more than 1 billion people worldwide lived with obesity, made up of 879 million adults and 159 million children. That total was more than double the adult cases and four times the childhood cases registered in 1990.
Obesity is correlated with cardiovascular disease, type 2 diabetes, obstructive sleep apnea, certain cancers, and osteoarthritis. Excess body fat underlies 64 percent of diabetes cases in men and 77 percent in women. The CDC has found obesity to be the single strongest risk factor for severe COVID-19 illness.
On average, obesity reduces life expectancy by six to seven years. A BMI of 30 to 35 reduces it by two to four years, while severe obesity at a BMI of 40 or above reduces it by ten years. In 2021, the World Health Organization estimated obesity caused at least 2.8 million deaths annually.
Obesity results from sustained positive energy balance, meaning more calories consumed than expended, combined with a resetting of the body's weight set point at a higher value. Contributing factors include diet, low physical activity, automation, urbanization, genetic susceptibility, medications, and endocrine-disrupting chemicals. People with two copies of the FTO gene weigh on average 3 to 4 kilograms more.
The main treatments are diet and exercise, with medication and surgery as further options. Six medications are approved for long-term use, including semaglutide, tirzepatide, and orlistat. Bariatric surgery is the most effective treatment, with one study showing 14 to 25 percent weight loss at 10 years and a 29 percent reduction in all-cause mortality.
The Lancet Commission on Obesity in 2019 estimated the global cost of obesity at $2 trillion a year, about 2.8 percent of world GDP. In the United States, medical costs attributable to obesity reached $190.2 billion in 2005, or 20.6 percent of all medical expenditures.