Assessment of Obesity

MARYAM JAMILAH BINTI ABDUL HAMID082013100002

IMS BANGALORE

Learning Outcome

• Definition of obesity

• Assessment of obesity

Obesity

A medical condition in which excess body

fat has accumulated to the extent that it

may have a negative effect on health,

leading to reduced life expectancy

and/or increased health problems.

Assessment of Obesity

• Body mass index (BMI)

• Anatomic differences in fat deposition

• Biochemical differences in regional fat

depots

• Size and number of fat cells

a) Obesity Index/Body Mass Index (BMI)

a) Obesity Index/Body Mass Index (BMI)A measure of relative weight based on an individual's mass andheight W

H2

W = Weight (kg)H = Height (m)or BMI= (weight in lb)/(height in inches)2 × 703

Nearly 2/3 of American adults are overweight and more than 1/3 are obese

1 stone = 14 pounds = 6.35 kg

1 kg = 2.2 pounds

• BMI is accurate most of the time

• However may overestimate or underestimate body fat.

• Does not distinguish between body fat and muscle mass, which weighs more than fat.

• Many NFL players have been labelled "obese" because of their high BMI, when they actually have a low percentage of body fat

b) Anatomic differences in fat deposition

b) Anatomic differences in fat deposition• It has a major influence on associated

health risks• Excess fat located in the central

abdominal area of the body is called android, “apple-shaped,” or upper body obesity(greater risk for hypertension, insulin resistance, diabetes, dyslipidemia, and coronary heart disease)

• Waist to hip ratioWomen > 0.8 Men > 1.0

• In contrast, excess fat in the lower extremities around

the hips or gluteal region is call gynoid, “pear-shaped,”

or lower body obesity

• Waist to hip ratio

Women < 0.8

Men < 1.0

• Commonly found in females (lower risk metabolic

disease)

• Some experts feel that the waist-to-hip ratio is better

than BMI as predictor of myocardial infarction

80-90% of fat stored in subcutaneous depots (under the skin,abdominal & lower body region)10-20% of fat stored in visceral depots (omental& mesenteric)

c) Biochemical differences in regional fat depots

• Men tend to accumulate the readily mobilizable

abdominal fat, they generally lose weight more readily

than women do

• Substances released from abdominal fat are absorbed via

the portal vein and, thus, have direct access to the liver

• Fatty acids taken up by the liver may lead to insulin

resistance and increased synthesis of triacylglycerols,

which are released as very-low-density lipoprotein (VLDL)

• By contrast, free fatty acids from gluteal fat enter the

general circulation, and have no preferential action on

hepatic metabolism

i. Abdominal fat cells

• much larger

• higher rate of fat

turnover

• adipocytes are

hormonally more

responsive than fat cells

in the legs and buttocks

ii. Lower body fat cells

• much smaller

• lower rate of fat

turnover

• adipocytes are

hormonally less

responsive than fat

cells in abdominal

c) Biochemical differences in regional fat depots

d) Number of fat cells

Hypertrophic and hyperplastic

changes thought to occur in severe

obesity

• When triacylglycerols are deposited in

adipocytes, the cells initially show a modest

increase in size

• However, the ability of a fat cell to expand is

limited, and when its maximal size is reached,

it divides

• Most obesity is, therefore, thought to involve

an increase in both the number and size of

adipocytes

• Fat cells, once gained, are NEVER LOST

• Thus, when an obese individual loses weight,

the size of the fat cells is reduced, but the

number of fat cells is not affected

• An obese individual, with increased numbers

of adipocytes, will have to reduce the size of

those fat cells in order to normalize fat stores

• These individuals will be in the doubly

abnormal state of having too many, too small

fat cells

• Formerly obese patients have a particularly

difficult time maintaining their reduced body

weight

• The observation that fat cells are never lost

emphasizes the importance of preventing

obesity in the first place

• Assessments of obesity are described

Conclusion

References

• Lippincott’s Illustrated Reviews: Biochemistry, 4th edition

• DM Vasudevan, Biochemistry Textbook for Medical Students

• http://health.howstuffworks.com/wellness/diet-fitness/weight-loss/bmi3.htm

• http://en.wikipedia.org/wiki/Obesity