Women generally have more subcutaneous fat than men, but men appear to suffer a greater cardiovascular risk from a given degree of fat than women. The distribution of body fat may be an indicator of this difference. This distribution around the abdomen, referred to as upper body obesity, is associated with increased cardiovascular risk factors. Lower body obesity is more typical in women, who tend to accumulate fat in the hips, gluteal regions, and extremities, a distribution that does not appear to be associated with increased cardiovascular risk factors. The mortality ratio has been shown to increase with the degree of obesity, and with its duration.
Obesity is the net result of an excess of energy consumption over expenditure.
Overeating is clearly a prominent contributor to obesity. Feeding behaviour occurs in response to hunger and to appetite inducedby the presence of food. Satiety and the resulting cessation of eating occur in response to certain hormones, nervous impulses, and absorbed nutrients signalling the brain. To loose weight, one must decrease caloric intake, increase caloric expenditure, or do both. Thus, the chief approaches to weight reduction involve behaviour change related to diet and exercise.