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Defintion

The definition of obesity is individuals whose body mass index (BMI) (weight in kilograms divided by the square of the height in meters; kg/m²) exceeds the age-gender-specific 95th percentile.

Etiology

Multifactorial :

· Genetic background

· Environmental stimuli

· Developmental processes.

An important factor in maintenance of body weight is the relationship between body weight and total energy expenditure.

Clinical Manifestations

In children, obesity is most often associated with tall stature, slightly advanced bone age, and somewhat early puberty. In most patients with obesity, rapid growth in height precludes the diagnosis of hypothyroidism and hypercortisolism. By contrast, hypothyroidism and cortisol excess cause delayed skeletal development, short stature, and delayed puberty. Many obese youth also have acanthosis nigricans, a hypertrophic hyperpigmentation of the skin most commonly seen on the posterior neck and in skin creases. This condition is associated with insulin resistance and a higher risk of developing type 2 diabetes.

Laboratory Findings, Diagnosis, and Differential Diagnosis

· Obesity can be diagnosed in most cases by simple inspection of the patient. If needed, BMI can be plotted on BMI growth curves to identify those who are over the 95th percentile. Early identification of children at risk includes the demonstration of early adiposity rebound.

· The most important tests in the evaluation and follow-up of obese patients are those that evaluate cardiovascular disease risk and diabetes risk. These include plasma lipid profiles, fasting glucose and insulin levels, and hemoglobin A1C. It may also be necessary to perform studies to test for sleep apnea.

· Hypothyroidism and hypercortisolemia can be ruled out by demonstrating normal free thyroxine and thyroid-stimulating hormone levels and 24 hr urinary free cortisol or diurnal salivary cortisol levels.

· If patients have severe early-onset obesity, out of proportion to the family history, one of the single gene defects mentioned earlier may need to be considered.

Complication

Obesity-associated co-morbidities include significantly increased risks for :

· Diabetes Mellitus

· Cardiovascular disease

· Cancer

· Respiratory disease (asthma, sleep apnea)

· Infertility

· Degenerative joint disease

· Proteinuria

· Depression

· Anxiety

· Discrimination both in social life and in the workplace.

Prevention

· Increasing physical activity.

· Changing dietary habits.

Treatment

Behaviour

· Reduction of dietary calories and fat

Diets that are lower in carbohydrates may be useful in some individuals, but the basic goal should be reduction in energy intake and increase in energy expenditure.

· Increasing dietary fiber.

· Increase in physical activity (regular aerobic exercise, decrease in television viewing and computer games).

Medication

Anti-obesity drugs are not approved for prolonged use or for use in youth.

The major classes of drugs are :

· Reduce food intake (monoamine oxidase inhibitors, sympathomimetic drugs)

· Increase energy expenditure (ephedrine, caffeine)

· Inhibit fat absorption (orlistat).

Surgery

Surgical therapy to reduce the volume of the stomach may be successful in the long term in some patients. Procedures to bypass the absorptive surfaces of the intestine have been associated with many complications, the most predictable being nutritional deficiencies.

Surgery to remove fat (liposuction), if used alone, is not a long-term solution. However, it may be a useful cosmetic adjunct in patients who are successful with diet and exercise, with or without surgical gastroplasty.