The obesity epidemic is one the most serious health problems in America today. The incidence of obesity has more than tripled since 1980 among children aged 2 to 19 years and has increased substantially among the rest of the population. Today, 27.0% of adults are obese. In the San Francisco-Oakland-Hayward metro area, 19.5% of adults are obese, the second lowest of any California metro and lower than the national obesity rate.

One of the main reasons for the rise in obesity in the United States is the growing share of Americans who do not exercise. A recent study found that while 1 in 2 jobs in 1960 required moderate physical activity, just 1 in 5 jobs today do. Americans also get less exercise outside of work. In San Francisco, an estimated 14.9% of adults report engaging in no leisure-time physical activity, lower than the national inactivity rate of 23.0%.

Overweight and obese individuals are likely to engage in other unhealthy behaviors. An estimated 10.7% of San Francisco adults smoke, lower than the national smoking rate of 17.0%. San Francisco’s smoking rate is the second lowest of all cities in California.

After smoking, obesity is the leading cause of preventable death in the United States. According to one study by researchers at the National Institutes of Health, individuals who are extremely obese — roughly 100 pounds over the recommended weight for a person of average height — are expected to live roughly 14 years less than Americans of normal weight. The life expectancy at birth in San Francisco is 81.5 years, longer than the U.S. average life expectancy of 78.5 years. An estimated 242 residents per 100,000 die prematurely in San Francisco, the third lowest incidence of premature death in California and lower than the national premature mortality rate of 474 deaths per 100,000 Americans.

One of the most common ways obesity can lead to death is through diabetes. Extra weight can place added pressure on the body’s ability to regulate insulin and blood sugar levels, increasing the likelihood of developing diabetes. Nationwide, 9.3% of all Americans have been diagnosed with the disease. In San Francisco, 8.5% of all residents have diabetes.

Obesity is correlated with income and education. Low-income individuals with less education are at the greatest risk of being overweight, as many lack the means to access healthy food, opportunities for exercise, and medical guidance. The obesity rate among Americans making less than $15,000 a year is 8 percentage points higher than for those earning at least $50,000 a year, and 11 percentage points higher among high school dropouts than college graduates. In San Francisco, 47.2% of adults have at least a bachelor’s degree, and the typical household earns $88,518 a year, both higher than the corresponding national figures of 30.6% and $55,775.