Degrees of obesity

A common sign of all forms of obesity is the excessive accumulation of adipose tissue in the body. To diagnose obesity and determine its degree, the body mass index (BMI) is used, which is obtained from the ratio of the body weight (in kilograms) and the growth rate (in meters) in the square:

BMI - Body mass (kg) Height (m) ²

BMI within 18.5-24.5 kg / m ² corresponds to normal body weight.

Classification of obesity by BMI (WHO, 1997)

Types of body weight	BMI kg / m 2	Risk of concomitant diseases
Deficiency of body weight	<18.5	Low (increased risk of other diseases)
Normal body weight	18.5-24.5	Normal
Overweight (pre-fat)	25.0-29.9	Increased
Obesity of the 1st degree	30.0-34.9	Tall
Obesity of the 2nd degree	35.0-39.9	Very tall
Obesity of the third degree	> 40.0	Extremely high

The BMI indicator is not reliable for children with an incomplete growth period, people over 65, athletes and people with very developed muscles, pregnant women.

BMI is used not only to diagnose obesity, but also to determine the risk of obesity-related diseases and determine the tactics of treating obese patients.

The nature of the distribution of fat tissue is determined by using the waist circumference / hip circumference ratio (OT / OB). The value of OT / OB for men> 1.0 and women 0.85 indicates the abdominal type of obesity. Studies of recent years have shown that a reliable sign of excessive accumulation of adipose tissue in the abdominal area is the waist circumference at a BMI <35. The waist circumference is also an indicator of the clinical risk of developing metabolic complications of obesity.

Waist circumference and risk of metabolic complications (WHO, 1997)

	Increased	Tall
Men's Women	> 94cm > 80cm	> 102 cm > 88cm

The examination of patients along with the definition of anthropometric parameters includes measurement of blood pressure, ECG examination, radiography of the skull, determination of total cholesterol levels, low and high density lipoproteins, triglycerides, fasting glucose or against a standard glucose tolerance test, fasting insulin, LH, FSH, PRL, E2, TTG, st. T4 (according to indications).

Differential diagnosis of obesity. Clinical and laboratory signs of increasing the activity of the hypothalamic-pituitary system (skin changes, redistribution of subcutaneous fat, arterial hypertension exceeding the excretion rate with urine of free cortisol) are often difficult to diagnose in patients with hypothalamic obesity, since such symptoms can be in patients with hypercorticism. In these cases, along with the radiography of the skull and spine, the determination of excretion in the urine of free cortisol, the cortisol content in the plasma for a day, a small sample with dexamethasone is administered: dexamethasone is prescribed at 0.5 mg (1 tablet) every 6 hours for two days. To determine the content of free cortisol in the urine, its daily amount is collected before the sample is performed and on the 2nd day of the study. In patients with hypothalamic obesity, the excretion of free cortisol against the background of dexamethasone decreases by no less than 50% of the initial value. With hypercorticism, this indicator does not change.

Higher content of ACTH and cortisol in the plasma and a slight increase in excretion of free cortisol in the urine detected in patients with a hypothalamic syndrome of the pubertal period, necessitates differential diagnosis with the disease or syndrome of Itenko-Cushing and the hypothalamic syndrome of the pubertal period. High growth, acceleration of physical and sexual development, differentiation of the skeleton, absence of osteoporosis of the bones of the skull and spine, normal circadian rhythm of cortisol secretion, positive reaction (by urinary excretion of free cortisol) to the administration of small doses of dexamethasone allow rejecting the diagnosis of hypercortisy.

[1], [2], [3], [4], [5], [6],