Weight management

Question 1

Weight statuses and their BMI range

Answer 1

1. Underweight < 18.5
2. Normal 18.5 - 22.9
3. Overweight 23 - 27.4
4. Obese ≥27.5

(This is according to healthhub, and for Asians since we have higher % bodyfat)

Question 2

Mainstay treatment strategy for weight management

Answer 2

Lifestyle modifications:
- Diet
- Exercise

Question 3

Risk factors for obesity (other than medical and genetic causes)

Answer 3

• Sedentary lifestyle
• Family lifestyle (which influence lifestyle of child)
• Smoking
• Age (older = less metabolism = more weight gain)
• Socio-economic issue (e.g. no place to exercise, unaware of healthy eating)

Question 4

Recommended waist circumference for males and females respectively?

Answer 4

• Males ≤ 90cm (35.5 in)
• Females ≤ 80cm (31.5 in)

Question 5

Recommended waist hip ratio for males and females repsectively?

Answer 5

• Males: ≤ 0.9
• Females: ≥ 0.85

Question 6

State the dosing regimen of orlistat for patients who require pharmacological aid for weight loss. State its forensic classification, minimum age, and limit in supply if applicable

Answer 6

Orlistat 60 - 120 mg TDS before meals, or up to 1h after meals

• Forensic classification: P-only
• Minimum age ≥ 18

Question 7

Maximum duration of therapy with orlistat

Answer 7

4 years

Question 8

Maximum daily dose of orlistat

Answer 8

360 mg (120 mg TDS)

Question 9

Mechanism of action of orlistat?

Answer 9

Reversible inhibitor of gastric and pancreatic lipase

(blocks up to 30% of fat absorption)

Question 10

Can orlistat be used as a monotherapy for weight loss?

Answer 10

No, only as an adjuct to lifestyle modification

Question 11

Name some drugs that may interact with orlistat, and management to avoid their interactions if possible

Answer 11

1. Levothyroxine: decreases levothyroxine concentration. Space at least 4h apart
2. Vitamin D (and other fat soluble vitamins): Decreases vitamin D absorption. Space at least 2h apart
3. Amiodarone: Decreases level of amiodarone. No established workaround to avoid interaction

Question 12

When should orlistat be discontinued?

Answer 12

Unable to lose 5% of initial body weight after 12 weeks

Question 13

Dosing regimen for phentermine

Answer 13

• Initial: 30 mg OD, half to 1h before breakfast
• Maintenance: 15 - 30 mg OD or 15 mg BD. Second dose should be given 10-14h before bedtime

Question 14

Maximum duration of phentermine, and total maximum cumulative duration. State if a drug-free interval is required and the reason for maximum duration + drug-free interval.

Answer 14

• Maximum duration: 12 weeks
• Maximum cumulative duration: 6 - 12 months
• Drug-free interval: 4-12 weeks
• Reason: Tolerance develops after a few weeks of therapy

Question 15

Mechanism of action of phentermine

Answer 15

Centrally acting appetite suppressant

Question 16

Side effects of phentermine

Answer 16

• Tachycardia and palpitations
• Increased BP
• Restlessness
• NNV, drymouth, abdominal pain
• etc.

Question 17

Goal rate of weight loss

Answer 17

0.5-1kg/week, 5-10% loss over 6 months