Obesity has dramatically increased in America due to many factors. It has caused an increase in heart disease, diabetes and certain cancers, and arthritis. An obese individual is one whose body fat is in excess and leads to a reduced life expectancy. BMI or body mass index compares height and weight. An obese individual's BMI exceeds 30 kg/m2. A sedentary lifestyle contributes greatly to obesity, as does eating "empty calorie" foods that provide little in the way of nutrition, but contain a lot of calories. The Centers for Disease Control and Prevention states that the number of obese children tripled from 1980-2010. The American diet is partially to blame. Two thirds of adults are overweight or obese in the U.S. Americans eat processed foods containing high levels of saturated fat. Americans eat a lot of fast food which is inexpensive but contains larger portions than normal and high levels of fat and salt. Many Americans do not eat enough whole grains, fruits and vegetables, fish oils and healthy fats. The U.S. government recommends that the daily amount of saturated fat in the American diet should decrease from 10% to 7% and their sodium intake be reduced from 2,300 mg to 1,500 mg. High sodium can lead to cardiovascular disease. Obesity will take a toll on the health care system as many children and adults suffer from the medical conditions that develop as a result of being overweight.