Obesity

Question 1

General info

Answer 1

Obesity occurs due to an imbalance between energy output and input. It is a state of increased body weight due to adipose tissue accumulation in a sufficient amount to produce a health risk. Central obesity comes with increased risk as compared to diffuse distribution of the adipose tissue. Especially important are the increased risks of hypertension and diabetes.

Question 2

Diagnosis of obesity

Answer 2

BMI: normal is 18.5-25, overweight is 25-30, obese is greater than 30.
Skinfold measurements
Body circumference, particularly waist-to-hip circumference ratio

Question 3

Clinical consequences of obesity

Answer 3

Insulin resistance and hyperinsulinemia - Type 2 DM
Hypertension
Coronary artery disease
Cancer, increased incidence of esophageal and kidney
Non-alcoholic steatohepatitis
Cholelithiasis
Hypoventilation syndrome - also called Pickwickian syndrome
Osteoarthitis, due to increased load on the joints; wear and tear
Markers of inflammation are increased in obese patients: such as CRP and TNF.

Question 4

What is “lipostat”

Answer 4

Lipostat is an internal mechanism which assist in the regulation in input and output of energy into our bodies. It regulates the body composition through neural and humoral factors.

Question 5

The Afferent/peripheral system of Lipostat

Answer 5

Major contributors to the Afferent/peripheral sensory system are: Leptin, adipose tissue, gut hormones, arcuate nucleus

Question 6

Leptin

Answer 6

Secreted from adipose tissue and travels to the Arcuate nucleus where it reduces food intake by stimulating POMC/CART neurons (which enhances energy output and weight loss) and inhibits NPY/AgRP neurons (which enhance food intake and weight gain). The opposite happens when there is inadequate stores of fat. When these pathways are balanced the patient has stable weight. Leptin also increases thermogenesis. Mutations in the LEP gene can lead to massive obesity. More commonly mutations in melanocortin receptor-4 is found in very obese patients.

Question 7

Adipose tissue

Answer 7

Produces other mediators, such as adiponectin, cytokines and steroid hormones. And so the adipose tissue plays a role in lipid metabolism, nutrition and inflammation.

Question 8

Gut hormones

Answer 8

Rapidly acting activators and terminators of eating
Ghrelin: produced in the stomach and rises before meals. Probably acts by stimulating the NPY/AgRP neurons in the hypothalamus. Increases food intake.
Peptide YY: secreted from endocrine cells in the ileum and colon in response to consumption of food. Probably acts by stimulating POMC/CART decreasing food intake.

Question 9

Arcuate nucleus

Answer 9

Processes and integrates the afferent signals and generates new signals transmitted by proopiomelanocortin and cocaine- and amphetamine-regulated transcript (CART) neurons and neuropeptide Y (NPY) and agouti-related peptide (AgRP) neurons.

Question 10

Efferent system of lipostat

Answer 10

Consists of the hypothalamic neurons regulated by the arcuate nucleus. These regulate the weight gain or loss and communicates with the forebrain and midbrain systems. Hypothalamic forms of obesity:
Dystrophia adiposogenitalis (Fröhlich-syndrome)
Laurence-Moon-Biedl syndrome
Prader-Willi-Labhart syndrome

Question 11

Dystrophia adiosogenitalis (Fröhlich-syndrome)

Answer 11

Obesity, hypogonadism, visual disturbances, skeletal malformation, white skin, intracranial tumor

Question 12

Laurence-Moon-Biedl

Answer 12

Laurence-Moon: obesity, spastic paraparesis, retinitis pigments, mental retardation, hypogonadism

Biedl-Barnet: Polydactily, retinitis pigmentosa, mental retardation, hypogonadism, renal malformations

Question 13

Prader-Willi-Labhart

Answer 13

Hypogonadism – seen in later topic

Question 14

Treatment of obesity

Answer 14

Weight Loss

Treatment of symptoms as they appear