O

OBESITY

The WHO definition of obesity is an abnormal or excessive accumulation of body fat that may impair health. It is regarded as a global health epidemic and a chronic disease. The outstanding cause of weight gain in exogenous obesity is excessive calorie intake coupled with lack of exercise. Useful measuring instruments include:

• body mass index (BMI): ‘healthy’ range is between 20 and 25 (BMI = weight (kg) ÷ height (m²))

• abdominal obesity—defined as a waist:hip circumference ratio (W/H ratio) of >0.85 in women and >0.95 in men—which is a better predictor of cardiovascular risk and other complications of obesity than BMI

• waist circumference: risk of comorbidity ♂>94 cm; ♀>80 cm

• single skin-fold thickness (>25 mm suggests increased body fat)

Management principles (WHO and NHMRC)

1. Reduction in energy intake

2. Change in diet composition, including fat intake to < 30% calorie intake

3. Increased physical activity, (e.g. walking 30 min/d or 10 000 steps/d (use pedometer))

4. Behavioural therapy

Rules

• Need a close supportive relationship

• Promote realistic goals—lose weight slowly

• Follow a healthy fat, high-fibre, reduced calorie intake (low sugar) diet.

• Allow normal foods with reduced quantity and frequency (e.g. eat ⅓ less than usual)

• Supportive counselling (never judgmental)

• Provide a list of ‘tips’ for coping

• Advise keep a food, exercise and behaviour diary

• Strict follow-up (e.g. fortnightly, then monthly) until goal weight achieved, then 3 mthly reviews

Pharmacotherapy (adjunct therapy)

Adverse effects can be problematic. Consider for those with BMI >30 and failed well-supervised lifestyle measures. The agents are:

• local, acting on GIT:

  • – bulking agents (e.g. methylcellulose)

  • – lipase inhibitors—orlistat (Xenical) 120 mg (o) tds ac (used with a low-fat eating program)

• centrally acting agents (not recommended):

  • – amphetamine derivatives (reduce hunger)

  • – phentermine 15–40 mg (o)/d (limited use)

• serotonin analogues (enhances satiety)

  • – fluoxetine 20–40 mg (o)/d

  • – sibutramine 10–15 mg (o)/d (monitor BP)

  • – sertraline 50–100 mg (o)/d

Bariatric surgery

Consider surgical intervention (e.g. Lap Band, sleeve gastrectomy and Roux-en-Y bypass)—perhaps the most effective treatment for significant obesity. It is recommended in those with a BMI >40 or >35 with severe comorbidities, especially diabetes (good evidence).

OBSESSIVE–COMPULSIVE DISORDER

• Psychological intervention, esp. cognitive behaviour therapy

• Refer for group therapy

• Any SSRI antidepressant (e.g. fluoxetine 20 mg (o)/d) is first-line pharmacological treatment—if required

• Second line: clomipramine 50–75 ...