Obesity

Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/ or increased health problems.

Or,

Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health (WHO).

* Pre-exam preparation for medicine, HN Sarker

Body mass index is a measure to determine the excessive adipose tissue. It is calculated as weight in kg divided by height in meter². Normal BMI is 18.5 to 24.9 kg/m².

* Long Cases in Clinical Medicine, ABM Abdullah Page: 621

* Davidson’s Principles and Practice of Medicine, 22nd edition Page: 117

If the relative weight is > 200% (BMI > 40 kg/m²), it is called morbid obesity. It is associated with 10 fold increase in mortality.

* Long Cases in Clinical Medicine, ABM Abdullah Page: 621

1. Central obesity—(abdominal, visceral, android or apple-shaped) obesity.
2. Generalized obesity—Subcutaneous fat accumulation causing generalized (gynoid or pear-shaped) obesity.

* Pre-exam preparation for medicine, HN Sarker

The ‘obesogenic’ environment

1. Increasing energy intake
   • ↑ Portion sizes
   • ↑ Snacking and loss of regular meals
   • ↑ Energy-dense food (mainly fat)
   • ↑ Affluence
2. Decreasing energy expenditure
   • ↑ Car ownership
   • ↓ Walking to school/work
   • ↑ Automation; ↓ manual labour
   • ↓ Sports in schools
   • ↑ Time spent on computer games and watching TV
   • ↑ Central heating

Potentially reversible causes of weight gain

1. Endocrine factors
   • Hypothyroidism
   • Cushing’s syndrome
   • Insulinoma
   • Hypothalamic tumours or injury
2. Drug treatments
   • Atypical antipsychotics (e.g. olanzapine)
   • Sulphonylureas, thiazolidinediones, insulin
   • Pizotifen
   • Corticosteroids
   • Sodium valproate
   • β-blockers

 Other causes:

• Genetic factors
• Psychological factors

* Davidson’s Principles and Practice of Medicine, 22nd edition Page: 117; Long Cases in Clinical Medicine, ABM Abdullah Page: 620

Endocrine causes of obesity are:

– Hypothyroidism

– Cushing’s syndrome

– Insulinoma.

* Pre-exam preparation for medicine, HN Sarker

Common drugs are—

• Tricyclic antidepressants
• Corticosteroids
• Sulfonylureas
• Sodium valproate
• Estrogen-containing contraceptive pill.

* Pre-exam preparation for medicine, HN Sarker

• Cushing syndrome,
• Laurence-Moon-Biedle syndrome,
• Prader-Willi syndrome,
• Pickwickian syndrome,
• Alstrom’s syndrome,
• PCOS (Polycystic ovary syndrome)

* Long Cases in Clinical Medicine, ABM Abdullah Page: 620

Fat cells release free fatty acids and also TNF-α which are responsible for insulin resistance. A new protein called resistin secreted by the fat cells, also causes insulin resistance.

* Long Cases in Clinical Medicine, ABM Abdullah Page: 621

As follows:

• Insensitivity to leptin presumably in hypothalamus.
• Neuropeptide Y induced hyperphagia.
• Deficiency of production or action of anorexigenic hypothalamic neuropeptides.
• Increased secretion of insulin and glucocorticoids.
• Mutation in the gene of PPAR-γ  accelerates differentiation of adipocyte and may cause obesity.

* Long Cases in Clinical Medicine, ABM Abdullah Page: 621

In any case of obesity, detail history of the patient, specially dietary history, physical activity or sedentary work, any drug, alcohol should be taken. Whether the weight gain is recent or rapid (to exclude secondary disease like Cushing’s syndrome or hypothyroidism). Then following routine investigations should be done:

• Fasting blood sugar
• Lipid profile (ideally in a fasting morning sample)
• Thyroid function test (FT3, FT4 , TSH)
• Investigate for Cushing’s syndrome (overnight dexamethasone suppression test or 24-hour urine free cortisol)
• Liver function test (elevated serum transaminases occur in patients with non-alcoholic fatty liver disease, USG of hepatobiliary system to see fatty liver)
• X-ray chest, ECG, echocardiography – to see cardiac status
• Lung function test for sleep apnea
• X-ray of the individual joints in osteoarthrosis
• In female, if PCOS is suspected, investigate accordingly (such as USG of ovary, serum FSH and LH).

* Long Cases in Clinical Medicine, ABM Abdullah Page: 621; Davidson’s Principles and Practice of Medicine, 22nd edition Page: 117

As follows:

• Hypothyroidism
• Cushing’s syndrome
• Metabolic syndrome.

 * Long Cases in Clinical Medicine, ABM Abdullah Page: 620

In the history, there is no cold intolerance, sleepiness, lethargy, etc. There is no nonpitting edema, no coarse puffy face, no slow relaxation of the ankle jerk.

* Long Cases in Clinical Medicine, ABM Abdullah

In Cushing’s syndrome, there is usually central obesity with relatively thin limbs, plethoric moon face, multiple purple striae, proximal muscular weakness, etc. All are absent in this case.

* Long Cases in Clinical Medicine, ABM Abdullah

Management of obesity:

1. Lifestyle modification
   • Maximize physics activity.
   • Changes in eating behaviour:
     • Food selection.
     • Portion size control.
     • Avoidance of snacking.
     • Regular meals to encourage satiety, and substitution of sugar with artificial sweeteners.
2. Diatery modification : Low fat diet. Avoid fatty food and fast food.
3. Drugs:
   • Orlistat: Inibits pancreatic and gastric lipases thereby decreases the hydrolysis of ingested triglycerides, reducing dietary fat absorption.
   • Sibutramine: Reduces food intake through β1-adrenoceptor and 5-HT2A/2C (5-hydroxytryptamine, serotonin) receptor agonist activity in the central nervous system
4. Surgery:
   • Vertical banded gastroplasty.
   • Laparoscoic banding.
   • Roux-en-Y gastric bypass.
5. Treatment of additional risk factors: Including smoking, excess alcohol consumption, diabetes mellitus, hyperlipidaemia and hypertension.

In some cases of morbid obesity (BMI >40 kg/m²) or BMI > 35 kg/m² and obesity related complications, after conventional treatment have failed.

* Long Cases in Clinical Medicine, ABM Abdullah Page: 622

As follows:

• Psychological – Low self esteem, depression.
• Mechanical – Osteoarthritis of knee and hips, back strain, varicose veins, urinary incontinence, hiatus hernia, abdominal hernia, flat foot.
• Hepatobiliary – Non-alcoholic steatohepatitis, cirrhosis, gallstones.
• Respiratory – Exertional dyspnea, obstructive sleep apnea, Pickwickian syndrome.
• Cardiovascular – Hypertension, atherosclerosis, ischemic heart disease, heart failure, thrombo embolism
• Stroke
• Metabolic – Diabetes mellitus (type 2), hyperlipidemia, atherosclerosis, hyperuricemia and gout.
• Increased cancer risk – breast, uterus, colorectal, prostate, ovary.
• Skin infection – groin and submammary candidiasis.
• Menstrual abnormalities.
• Increased morbidity and mortality.
• Postoperative problems.
• Accident proneness.

 * Long Cases in Clinical Medicine, ABM Abdullah Page: 621