- Obesity is increasingly common. For example, 17% of adults in the UK are classed as obese (BMI >30). The changes in metabolism associated with obesity are central to the pathophysiology of insulin resistance and type II diabetes; obesity is also an important risk factor for hypertension and coronary artery disease; and there is an increased incidence of osteoarthritis of weight-bearing joints.
- Medical causes of obesity (e.g. Cushing's syndrome, hypothyroidism) are rare, but should be excluded before starting treatment.
- Weight gain results from an imbalance between energy intake and expenditure. The only long-term solution is to reduce intake and increase energy expenditure through exercise. Diets should be low in calories, but not very low. Aim for a total daily intake of around 1000 kCal. In patients who are motivated to lose weight, drug treatments can increase the amount of weight lost as part of a diet and exercise programme. Drug treatments are ineffective if given alone, and should not be continued for long periods (see individual articles for details).
- Ideally, obesity should be managed by a multidisciplinary team, but in many countries such expertise and resources are scarce.
- NICE has advised that patients with a (e.g. BMI >30 kg/m2 should receive treatment. Patients with complications arising from obesity (obstructive apnoea, hypertension, type II diabetes) have most to gain from weight reduction and represent a priority group for treatment. Consider treatment in this group if they have a BMI >28 kg/m2.
- Treatment of obesity should form part of a wider assessment of a patient's lifestyle and risk factors for cardiovascular disease. Help with stopping smoking can be particularly beneficial (see p. 236).
- Many patients are desperate to lose weight but find it difficult to modify their lifestyle; these patients are particularly vulnerable to those offering miracle treatments. Many of these contain amphetamines, diuretics, and thyroid hormones. They have no place in the treatment of obesity and can cause significant harm.
- Fenfluramine, dexfenfluramine, and phenteramine are centrally-acting appetite suppressants structurally related to amphetamines. They have been withdrawn because they can cause pulmonary hypertension.
- Bulk-forming supplements (e.g. methylcellulose) are unlikely to cause harm, but there is little evidence that they are effective.
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