Obesity is on the rise throughout the world. Even though the developed countries are affected more than the developing countries, the developing countries are catching up very fast.

Obesity is a major cause of morbidity and mortality. The rise in the incidence of obesity is unfortunate, because it is preventable.

Numerous complications have been linked to obesity, some examples are increased risk of  cesarean delivery, gestational diabetes, gestational hypertension, complications of anaesthesia and post-operative wound infections.

Maternal obesity also increases the risk of fetal mortality and morbidity. It is also thought that maternal obesity could increase the risk of nural tube defects.

Definition of Obesity:

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.

Various methods have been used to define and classify obesity.

At the moment modern medicine accepts the Quetelet index for the definition and classification of obesity. The Quetelet index is weight/(height x height) . Weight in kilogram’s and  height in meters. The quetelet index gives the body mass index( BMI).

Obesity is labeled when the BMI is >30 Kg/m sq

Who Grading of  Body Mass Index (BMI)

BMI < 16 indicates grade 3 thinness

BMI    16.0-16.99 indicates grade 2 thinness

BMI    17.0-18.49 indicates grade 1 thinness

BMI    18.5-24.99 is the normal range for an individual

BMI < 25.0-29.99 indicates grade 1 overweight

BMI < 30.0-39.99 indicates grade 2 overweight

BMI > 40.00 indicates grade 3 overweight

Freedman’s classification of BMI

Class I ( BMI 30-34.9 Kg/m sq )

Class II (BMI 35 -39.9Kg/ m sq)

Class III (BMI >40 Kg/ m sq)

Incidence of Obesity

Obesity is a pandemic. It is a public health problem. There has been an increase of 75 percent of obese adults over the last two decades. Obesity now affects  schoolchildren as well as all groups of adults including pregnant women. 15% of children (6 to 11 years of age) and 21% of adolescents (12 to 19 years of age) are now overweight.

Approximately 300,000 adults die each year from obesity related cause. Women who are obese have a two fold increase risk of heart failure and mortality risk from cardiovascular disease. The incidence of cardiovascular diseases also increases with increasing BMI. Obesity is perhaps the most prevalent form of  malnutrition.

Criteria used to assess obesity:

1)Body Weight

It is conventional to accept +2 SD (standard deviations) from the median weight for height as a cut off point for obesity.

a) Body Mass Index (Quetelet Index)

= Weight(Kg)/ height x height(m)

b) Ponderal Index

=Height (cm)/  cube root of body weight (Kg)

c)Broca Index

=Height (cm) minus 100 eg if a person’s height is 155cm his ideal weight is (155-100)=55Kg.

d)Lorentz’s formula

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

e) Corpulence Index

=Actual weight/ Desirable weight

This should not exceed 1.2

2) Waist Circumference and Waist : Hip Ratio (WHR)

This is very important because it does not take into consideration the height of an individual , but it still relates closely to the BMR WHR.

This tries to estimate the intra-abdominal fat mass and total body fat.

The waist circumference is measured at the mid-point at the lower border of the rib cage and the iliac crest.

It is now established that that a high WHR (>1.0 in men and >0.85 in women) indicates abdominal fat accumulation.

3) Skin Fold Thickness

This index is not popular any more because it is difficult to repeat and get the same result in the same individual.

This method takes into consideration that a large proportion of total body fat is located just under the skin.

Different types of calipers are  used for this purpose (eg Harpenden Skin Callipers).

Measurements are taken at all four sites- ie mid-triceps, biceps, subscapular and suprailiac regions. The sum of the measurements should be less than 40mm in boys and 50 mm in girls.

References:

Obesity and Pregnancy -Chapter 33 by Rani Akhil Bhat .Medical Disorders in Pregnancy- An Update .edited by Hiralal Konar and Pralhad Kushtagi. Federation of Obstetric and Gynaecological Societies of India.First Edition.

WHO 2000 No. 894

WHO 1995 No 854

FAO/WHO/UNU 1985 No. 724- Energy and protein requirements.

Chapter 6 Epidemiology of Non- Communicable diseases -Park’s Textbook of Preventive and Social Medicine by K Park.

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