OBESITY

2. • Obesity is an abnormal increase in the body
weight due to excessive fat deposition.
• Obesity is basically a disorder of excess
calorie intake-overeating.
• Overeating-coupled with lack of physical
exercise-contribute to obesity.

3. • BMI is calculated as the weight (in kilograms)
divided by the height (in meters2).
BMI (kg/m2) =
Weight (kg)
____________
Height (m2)

4. • Grade I obesity or overweight - BMI 25-30 kg/m2
• Grade ll or clinical obesity - BMI > 30 kg/m2
• Grade lll or morbid obesity - BMI > 40 kg/m2
• Obesity is associated with many health
complications e.g. T2DM, CHD, hypertension,
stroke, arthritis, gall bladder diseases.

5. • Obesity has genetic basis.
• One gene namely ob gene, expressed in
adipocytes (of white adipose tissue)
producing a protein called leptin is closely
associated with obesity.
• Leptin is a body weight regulatory hormone.
• lt binds to a specific receptor in the brain &
functions as a lipostat.

6. • When fat stores in the adipose tissue are
adequate, leptin levels are high.
• This signals to restrict the feeding & limit fat
deposition.
• Leptin stimulates lipolysis & inhibits lipogenesis.
• Any genetic defect in leptin or its receptor will
lead to extreme overeating & massive obesity.
• During starvation, leptin levels fall which
promote feeding & fat production & its
deposition.

7. • White adipose tissue:
• The fat is mostly stored & this tissue is
metabolically less active.
• Brown adipose tissue:
• The stored fat is relatively less but the tissue is
metabolically very active.
• Brown adipose tissue possesses high
proportion of mitochondria & cytochromes but
low activity of ATP synthase

8. • Mitochondria of brown adipose tissue - the
oxidation & phosphorylation are not coupled
• Mitochondrial oxidation produces more heat
& less ATP.
• A specific protein-Therhogenin
• Thermogenin functions like an uncoupler &
dissipates the energy in the form of heat &
blocks the formation of ATP.

9. • Textbook of Biochemistry-U satyanarayana