Obesity is when a person is carrying too much body fat for their height and sex. A person is considered obese if they have a Body Mass Index (BMI) - weight in kilograms divided by their height in meters squared - of 30 or greater. Obesity can happen when you eat more calories than you burn off over a period of time. To most people, the term "obesity" means to be very overweight. Health professionals define "overweight" as an excess amount of body weight that includes muscle, bone, fat, and water. "Obesity" specifically refers to an excess amount of body fat.

Abdominal Obesity and Limb Obesity

Depending on where fat is stored on the body, obesity can be divided in to abdominal obesity and limb obesity. Abdominal obesity is when fat is mostly distributed over the abdomen and back, and limb obesity is when fat is concentrated around the thighs, arms, legs, and buttocks. Abdominal obesity occurs mainly in men; limb obesity occurs primarily in women.

Hereditary
Obesity tends to run in families, which could signify a genetic cause, or, simply a lifestyle cause. People within the same family tend to share similar diet and exercise habits.
ENVIRONMENTALLY INDUCED OBESITY
Environmental factors associated with obesity include recreational eating, cultural and family eating patterns, job environments that provide or encourage the use of calorie-dense foods, the social role of eating (e.g., dinner parties), and sedentary patterns of employment and recreation.

Constitutional Obesity

Obesity starts from infancy to adult. Usually they have family history of Obesity. They have very good appetite from half a year after birth and body fat cell number begins to increase. Their metabolism is slow and synthesis exceeds catabolism. There will be poor cure effect by limiting diet and strengthening exercise. They are not sensitive to insulin.

Treatment

Successful programs for weight loss reduction and maintenance should be started and followed under the care of a physician and/or a nutritionist. A weight-loss program may include:
Exercise (the Surgeon General has called for 30 minutes of physical activity on most days of the week)
A low-fat, high-complex carbohydrate, high fiber diet
Behavior modification to change eating behavior
Social support
Medications
Diet Therapy
Lifestyle modifications such as increasing physical activity and decreasing calorie intake are recommended instead of "dieting." Crash diets should definitely be avoided. The best approach to changing your diet is to talk to your doctor to find out what is best for you. Your doctor can provide you with dietary guidelines or refer you to a dietician for further help. Dietary guidelines will differ for each person depending on height, weight, concurrent health conditions, and desired amount of weight loss.
Potential Benefits of Medication Treatment
Over the short term, weight loss in obese individuals may reduce a number of health risks. Studies looking at the effects of weight-loss medication treatment on obesity-related health risks have found that some agents lower blood pressure, blood cholesterol, and triglycerides (fats) and decrease insulin resistance (the body's inability to use blood sugar) over the short term. However, long-term studies are needed to determine if weight loss from weight-loss medications can improve health.