A simplified presentation about obesity, it's causes, complications and management

1. Obesity
5th year medicine (2016)
Prepared by: Dr.Yousef Biuk

2. Definitions
– Obesity is a state of excess adipose tissue mass.
(Harrison’s :17th)
– Obesity is a disease of caloric imbalance that results from
an excess intake of calories above their consumption by
the body. (Robbins : 8th)
– The WHO definition is:
– a BMI greater than or equal to 25 is overweight
– a BMI greater than or equal to 30 is obesity.

3. Did you know?
– Worldwide obesity has more than doubled since 1980.
– In 2014, more than 1.9 billion adults, 18 years and older, were
overweight. Of these over 600 million were obese.
– Overall, about 13% of the world’s adult population (11% of men and
15% of women) were obese in 2014.
– In 2014, 39% of adults aged 18 years and over (38% of men and 40%
of women) were overweight.
– 42 million children under the age of 5 were overweight or obese in
2013.
– About 80% of obese adolescents will become obese adults.
– Obesity is the leading cause of preventable death, next to
smoking!

4. BMI (Quetlet’s index)
– Body mass index (BMI) is a simple index of weight-for-
height that is commonly used to classify overweight and
obesity in adults. It is defined as a person's weight in
kilograms divided by the square of his height in meters
(kg/m2).
– BMI = Weight (kg) / Height (m2)
– Values are age independent & same for both sexes.
– At similar BMI, fat content in women > men
– Morbidity and mortality increase with BMI similarly for
men and women

5. WHO classification
BMI Classification
<18.5 Under weight
18.5-24.9 Normal weight
25-29.9 Overweight
30-34.9 Class I obesity
35-39.9 Class II obesity
≥ 40.0 Class III obesity

6. Other indices
– Broca’s index = Height (cm) – 100
– Corpulance index = Actual weight / Desirable weight
– Ponderal index = Height (cm) / Weight3 (kg)3
– Lorentz’s formula = Height (cm) – 100 – Height (cm) – 150
2(women) or 4(men)

7. Other methods
– Waist circumference: >88 cm in women
>102 cm in men
– Leads to increased risk even if weight/BMI normal
– Reflects visceral adiposity that releases pro-inflammatory
cytokines
– Waist-hip ratio > 0.85 for women reflects central obesity
> 0.9 for men
– Anthropometry (skin fold thickness):
– Harpenden skin calliper
– < 40 mm in males, < 50 mm in females

8. Types of obesity
– Android
(Abdominal/Central):
Apple shaped
– Gynecoid (Peripheral):
Pear shaped

9. Causes of obesity
– Lack of Energy Balance
– Genes and Family History
– Endocrine: Hypothyroidism, Cushing's syndrome, and PCOD
– Drugs: corticosteroids, tricyclic antidepressants,
antipsychotics, lithium, and anti-convulsants (sodium
valproate), anti-histamines (cyprohepatidine)
– Emotional Factors
– Alcoholism
– Smoking cessation

10. Other causes
– Pregnancy
– Lack of Sleep
– An Inactive Lifestyle
– Work schedules.
– Lack of access to healthy foods
– Food advertising
– Lack of neighborhood sidewalks and safe places for
recreation

11. Energy balance
1. Afferent /peripheral system:
– Generates signals from various sites
– Composed of leptin , adiponectin - by fat cells, ghrelin from
stomach, peptide YY (PYY) from ileum, colon, insulin from
pancreas

12. Energy balance
2. Arcuate nucleus in hypothalamus:
– Processes & integrates neuro-humoral peripheral signals
– Generates efferent signals
– Composed of 2 subsets of first order neurons:
– These first order neurons communicate with second order
neurons

13. Energy balance
3. Efferent system:
• Carries signals from second order neurons of
hypothalamus to control food intake and energy
expenditure

15. Leptin
– Produced by adipocytes
– Binds to specific receptors on arcuate nucleus in the
hypothalamus
– Product of ‘ob’ gene
– Provides signal for “energy sufficiency”.
– Abundant fat  Leptin secretion
– Regulated by insulin stimulated glucose metabolism
– Stimulates thermogenesis, activity, energy expenditure

16. Adiponectin
– Produced mainly by adipocytes
– Low levels in obesity
– Stimulates fatty acid oxidation
– “Fat-burning molecule”
– ↓ fatty acid influx in liver, liver glucose production
– Protects against Metabolic syndrome

17. Complications of obesity
increased risk of:
– Cardiovascular diseases (Stroke, CAD, Phlebitis etc.)
– Type II diabetes
– Hyperlipidaemia
– Hypertension
– Cancer (breast, endometrial, colonic etc.)
– Osteoarthritis
– Biliary disease, NASH and cirrhosis
– Obstructive sleep apnoea & Type II respiratory failure
– Depression & Social isolation

19. Cardiovascular diseases and
Type 2 Diabetes
– Obesity is an independent risk factor for CAD, CHF
– Waist – Hip ratio is the best predictor
– Abdominal obesity is associated with atherogenic lipid
profile and cardiovascular diseases
– Hypertension
– About 80% of patients with type 2 DM are obese
– Obesity leads to insulin resistance

20. Metabolic syndrome
– Abdominal obesity
– Insulin resistance
– Hypertriglyceridemia
– Low serum HDL
– ↑ risk of CAD
– Seen more in Indians, probably due to low levels of
adiponectin

21. Management of obesity
– Aims
– Diet
– Exercise
– Pharmacotherapy
– Bariatric surgery

22. Aims of weight loss
– Normalise body weight
– Improved mobility and quality of life
– Improved health and reduced mortality
– Loss of 5-10% body weight beneficial in reducing
cardiovascular disease
– Diabetic prevention program – 5-6% weight loss in
BMI>34kg/m2 lead to 34% reduction in incidence of diabetes

23. Diet
– Types of diets
– Low calorie diets (500kcal/day deficit)
– Very low calorie diets (less than 800kcal/day total) not
recommended for >14 weeks
– Low carbohydrate, high protein diets
– Low fat diets

24. Exercise
– Helps to mobilise fatty acids from stored fat metabolised
to produce energy
– Exercise increases energy expenditure
– 30-45 mins of moderate exercise 3 times/week burns
150kcal/day (1000kcl/week)
– Any exercise – walking, swimming, cycling that increases
HR and makes patient breathless
– Exercise alone results in 2-4% reduction in BMI
– Combined with dietary modification results in greater
weight loss and better maintenance.

25. Pharmacotherapy
– Sibutramine:
– Nor-epinepherine and serotonin reuptake inhibitor
– MOA – appetite suppression and thermogenesis
– Dose: 10-20mg/day
– Side effects: hypertension, tachycardia, insomnia
– Contraindications: use with SSRI
– Average weight loss of 4.6kg vs placebo at 1 year
– Minimal effect on HbA1C
– No deaths on sibutramine

26. Pharmacotherapy
– Orlistat:
– Reversible lipase inhibitor
– Prevents absorption of 30% dietary fat
– Inhibits fat soluble vitamin absorption
– Side effects: steatorrhea, bloating, diarrhoea, faecal
incontinence, flatulence
– Meanwt loss 2.75kg vs placebo after 12 months treatment

27. Newer therapies
– Incretin-mimetics and DPP-4 inhibitors
– Incretins:
– Glucagon like peptide 1 (GLP-1) produced in l-cells of distal
small intestine
– Glucose dependent insulinotrophic polypeptide (GIP)
produced in k-cells of proximal small intestine
– This response is reduced or absent in those with type II
DM
– Type II DM tends to cause rise in post-prandial plasma
glucose

28. GLP-1 agonists
– Exenatide 5-10mcg bd sc
– Liraglutide
– Reduce HbA1C significantly by 0.6-1.1%
– Significant weights loss
– 3-5% body weight
– Appears sustained and progressive
– Dose dependent
– Less pronounced on liraglutide

29. DPP-4 inhibitors
– Sitagliptin licensed 2007 – 100mg daily
– Vildagliptin licensed 2008 – 50mg bd
– Use in TIIDM patients not controlled by SU and MF
– Reduction in HbA1c 0.5-1.0% vs placebo
– Caution in those with impaired hepatic function
– Some reports of hypersensitivity and Stevens-Johnson
Syndrome

30. Bariatric surgery
– First procedures 1950s
– Jejunoileal bypass
– Becoming increasingly common
– Procedures increased 6-fold in from 1996-2000 in California
– 140,000 performed in USA in 2004
– 2 procedures now commonly performed
– Roux-en-Y & Adjustable vertical banding gastroplasty
– >30kg weight loss for both procedures per year

31. Roux-en-Y
– Laparoscopic or open procedure
– Most common procedure worldwide in 2002 (65%)
– Causes malabsorption
– procedure involves creating a stomach pouch out of a
small portion of the stomach and attaching it directly to
the small intestine bypassing a large part of the stomach
and duodenum.

33. Adjustable vertical banding
gastroplasty
– Restrictive procedure
– 25% of procedures carried out worldwide
– Both a band and staples are used to create a small pouch
– A vertical pouch is created by stapling the back wall of the
stomach at the esophago-gastric junction
– The end of the pouch is constricted with a band or a ring

35. Thank you