It is excessive accumulation of body fat in and on the body. The usual cause is the consumption of more calories than the body can use. This simple explanation, however, hides a great deal of theory about its cause. It is probably true that some of us put on fat more readily than others. This may be because obese people are more interested in food or that they expend less energy. This latter theory may account for obesity in only a small minority of overweight persons. Overeating may be a habit culturally imposed by family custom, may be an occupational hazard (e.g., people who cook for a living), follow by immobilization, can be stimulated by certain drugs, or may be determined by cultural family environment, a sedentary lifestyle, or temperament. Obesity, like underweight, is a condition with multiple causes. Some people have a metabolic rate that is lower than average (e.g. they may feel cold sooner than others). Some of the effects of obesity are a reduced life expectancy, and a higher disposition to certain diseases and disabilities. Diabetes of the middle-aged is strongly associated with obesity, and obesity in women is associated with gallbladder disease. Other causes of obesity are: eating when lonely, sad or stressed, being pressured to eat by friends or family, or using food for recreation.