What causes someone to go from overweight to obese?

About 30 lb over. Obesity is a bmi over 30. For most, that is about 30 lb over ideal weight. If you are 5 ft 5 in, your ideal weight us 150lb. So, if you weigh over 180, you would fall into the "obese" category. Of course, you can check a bmi calculator for your specific height and weights: http://www. Nhlbisupport. Com/bmi/.