Obesity means having too much body fat. Obesity occurs over time when you eat more calories than you use. The balance between calories-in and calories-out differs for each person. Factors that might affect your weight include your genetic makeup, overeating, eating high-fat foods, and not being physically active. Being obese increases your risk of diabetes, heart disease, stroke, arthritis, and some cancers.
Click here for more information. http://www.nlm.nih.gov/medlineplus/obesity.html