E5 - Obesity Flashcards
What is obesity?
- Too much body fat
- Too much fat in the ‘wrong’ place
- Energy intake > Energy requirements
How can obesity be measured?
- BMI (weight in kg/height in m^2)
- Skin folds
What is assumed when measuring skin folds, and where is it measured?
- Assumes constant relationship between subcutaneous and total body fat
- Can be measured all over the body; biceps + triceps commonly used
What are the consequences of obesity on the body?
- Increases BP
- Increases plasma cholesterol
- Is a major risk factor for CHD
- Increases risk of T2DM (additional risk factor for CHD)
How is waist circumference used to predict risk?
- Good measure of intra-abdominal fat
- If apple or pear-shaped = fat sitting on waist
- Greater risk of complications if apple-shaped
How is obesity treated?
- Dietetic treatment
- Drugs
- Surgery
What dietetic treatments are availible?
- Very low calorie diets (VLCDs)
- Individualised modest energy restrictive diet
What do VLCDs involve and its respective advantages/disadvantages?
- Commercially-prepared diet typically 500 kcal/day for several days/weeks (max 12 weeks)
- Medical supervision only
- For v. obese patients that need to lose weight quickly (e.g. life threatening/in order to undergo surgery)
- Milkshake-type preparation (protein, vitamins, minerals)
Adv:
- Rapid weight loss if compliant
Dis:
- Not teaching healthy eating
What do Individualised Modest Energy Restrictive Diets entail?
- Provides 500 kcal/day less than calculated energy balance
- Slower weight loss, but based on healthy eating guidelines (patient education)
- Provides correct balance of nutrients
- Based on age/sex/weight
What is the only current POM drug licensed to treat obesity and its mechanism of action?
Orlistat (tetrahydrolipostatin):
- Inhibits gastric & pancreatic lipase
- Thus preventing metabolism of fat; not absorbed and excreted in faeces
- 30% lipase inhibition at normal therapeutic dose (= losing 2kcal/day)
How should Orlistat be taken and what is its side effect profile?
- To be taken before each meal
- Combine with a low fat diet
Side effects:
- Steatorrhoea (fatty, foul faeces; can result in leakage)
- Reduced absorption of fat = monitor fat soluble vitamins
What criteria must a patient fall under to be prescribed Orlistat?
- BMI > 30 kg/m^2
- Or BMI > 28 kg/m^2 with other risk factors e.g. T2DM, hypercholesterolaemia, hypertension
- Treatment only continued after 12 weeks if weight loss exceeds 5%
What is the ideal weight loss target?
- 5-10% of original weight
- MAX weekly weight loss of 0.5 - 1kg
What were the other POMs licensed (until Jan 2010 and Oct 2008 respectively)?
- Sibutramine
- Rimonabant
What is the mechanism of action of Sibutramine (suspended Jan 2010) and its side effect profile?
- Combined NA and 5HT uptake inhibitor
- Appetite suppressant
- Herbal products often contain it
Side effects:
- Increases SNS activity, can raise BP (increased NA in periphery as well as brain)
- Increases heart rate slightly
