Obesity may be defined as an abnormal growth of the adipose tissue due to an enlargement of fat cell size (hypertrophic obesity) or an increase in fat cell number (hyperplastic obesity) or a combination of both. Body mass index is used to express obesity.

“Abdominal fat distribution” or “android obesity” are at increased risk from those, in which fat is more evenly and peripherally distributed around the body, which is called as “gynoid” fat distribution.

Epidemiological determinants:

AGE:

Obesity is mostly increase with age and can occur at any phase of life. Childs which are obese in childhood are at more risk that of obese in elder age. About one-third of obese adults have been so since childhood.

SEX:

Women generally have higher rate of obesity than men, although men may have higher rates of overweight. It has been claimed that woman’s BMI increases with successive pregnancies. The recent suggest that this increase is about 1kg per pregnancy.

GENETIC FACTORS:

The profile of fat distribution is also characterized by a significant heritability level of the order of about 50 per cent of the total human variation. Twin studies have shown a close correlation between the weights of identical twins even when they are reared in dissimilar environments.

PHYSICAL INACTIVITY:

Evidence that regular physical activity is protective against unhealthy weight gain. Where as sedentary lifestyle particularly sedentary occupation and inactive recreation such as watching television promote it, physical activity and physical fitness are important modifiers of mortality and morbidity related to overweight and obesity.

SOCIO-ECONOMIC STATUS:

There is a clear inverse relationship between socio-economic status and obesity.

EATING HABITS:

The content of diet, the frequency of diet and the energy gain from diet are all factors in the etiology of obesity. A diet containing more energy than needed may lead to prolonged post-prandial hyperlipidemia and to deposition of triglycerides in the adipose tissue resulting in obesity.

PSYCHOSOCIAL FACTORS:

Psychosocial factors are deeply involved in the aetiology of obesity. Overeating may be a symptom of depression, anxiety, frustration and loneliness in childhood as it is in adult life. Excessively obese individuals are usually withdrawn, self-conscious, lonely and secret eaters.

FAMILIAL TENDENCY:

Obese parents have most probably obese childs, because obesity runs in family.

ENDOCRINE FACTORS:

These may be involved in occasional cases, e.g., Cushing’s syndrome, growth hormone deficiency.

ALCOHOL:

A recent review of studies concluded that the relationship between alcohol consumption and adiposity was generally positive for men and negative for women.

EDUCATION:

In most affluent societies, there is an inverse relationship between educational level and prevalence of overweight.

SMOKING:

In most of population smockers have less weight as compare to ex-smocker.

Use of BMI to classify obesity:

It is defined as the weight in kilograms divided by the square of the height in meter (kg/m2).

Classification	BMI	Risk of comorbidities
Underweight	< 18.50	Low (but risk of other clinical problems increased)
Normal range	18.50-24.99	Average
Overweight	>25.00
Pre-obese	25.00-29.99	Increased
Obese Class I	30.00-34.99	Moderate
Obese class II	35.00-39.99	Severe
Obese class III	>40.00	Very severe

INTRA-ABDOMINAL (CENTRAL) FAT ACCUMULATION AND INCREASED RISK:

Compared with subcutaneous adipose tissue, intra-abdominal adipose tissue has more cells per unit mass, higher blood flow, more glucocorticoid (cortisol) receptors, probably more androgen (testosterone) receptors, and greater catecholamine-induced lipolysis. These differences make intra-abdominal adipose tissue more susceptible to both normal stimulation and changes in lipid accumulation and metabolism.

Assessment of obesity:

Before we consider assessment of obesity, it will be useful to first look at body composition as under;

the active mass (muscle, liver, heart etc.)
the fatty mass (fat)
the extracellular fluid (blood, lymph, etc.)
the connective tissue (skin, bones, connective tissue)

Although obesity can easily be identified at first sight, a precise assessment requires measurements and reference, standards. The most widely used criteria are:

BODY WEIGHT:

Body weight, though not an accurate measure of excess fat, is a widely used index. In epidemiological studies it is conventional to accept + 2 SD (standard deviations) from the median weight for height as a cut-off point for obesity. For adults, some people calculate various other indicators such as:

(1) Body mass index (Quetelet’s index):

Weight (kg)/Height2(m)

(2) Pondera/ index:

Height (cm)/Cube root of body weight (kg)

(3) Brocca index = Height (cm) minus 100

For example, if a person’s height is 160 cm,

his ideal weight is ( 160-100) = 60 kg

(4) Lorentz’s formula:

Ht (cm) 100 * Ht (cm) – 150/2 (women) or 4 (men)

(5) Corpulence index:

Actual weight/Desirable weight

SKINFOLD THICKNESS:

A large proportion of total body fat is located just under the skin. Since it is most accessible, the method most used is the measurement of skinfold thickness.

WAIST CIRCUMFERENCE AND WAIST: HIP RATIO (WHR)

the mid-point between the lower border of the rib cage and the iliac crest, is point where Waist circumference is measured. It is a easy and simple measurement that is not related to height, similar closely with BMI and WHR and is an approximate index of intra-abdominal fat mass and total body fat.

Hazards of obesity:

Greatly increased	Moderately increased	Slightly increased
Type 2 diabetes	CHD	Impaired fertility
Gall bladder disease	Hypertension	Cancer (breast cancer in postmenopausal women, endometrial cancer, colon cancer)
Dyslipidemia	Osteoarthritis	Reproductive hormone abnormalities
Insulin resistance	Hyperuricemia and gout	Polycystic ovary syndrome
Breathlessness		Low back pain .due to obesity
Sleep apnea		Increased risk of anesthesia .complications
		Fetal defects associated with maternal obesity

Prevention and control:

Weight control is widely defined as approaches to maintaining weight within the ‘healthy’ range of body mass index of 18.5 to 24. 9 kg/m2 throughout adulthood. This can be achieved by dietary changes, increased physical activity and a combination of both.

DIETARY CHANGES:

Energy dense food like simple carbohydrates and fats should avoid; the fiber content in diet should be increased by eating simple un-refined fiber.

INCREASED PHYSICAL ACTIVITY:

This is an important part of weight reducing programme. Regular physical exercise is the key to an increased energy expenditure.

How To Survive Obesity