Diagnosis

1. The general practitioner should regularly assess the body weight of his patients in order to identify overweight (BMI 25 till 29,9) and obesity (BMI of 30 or more) in a timely fashion (level of evidence 3).
2. Obesity is associated with an important amount of complications and co-morbidity. The general practitioner should therefore systematically assess the waist circumference of his obesity patients in order to determine the obesity type and the associated health risk (level of evidence 1).
3. It is important to identify patients with binge eating disorder and to refer adequately to a psychiatrist or psychologist specialised in the treatment of binge eating disorders (level of evidence 3).
4. Before starting a treatment, the general practitioner should explore to what extent the patient is motivated to change (according to the ‘Stages of Change’ model of Prochaska & DiClemente). Motivational interviewing is a good method to motivate a patient for behavioural change (level of evidence 3).

Treatment

1. The treatment of obesity is individual and stepwise. A combination of diet, behavioural and movement recommendations is more effective in weight reduction and - conservation then each of these treatments separately (level of evidence 1).
   It is sensible and feasible to reach a weight loss of 5 à 10% in six up to twelve months (level of evidence 1).
2. Diet counselling starts with the patient’s feeding pattern and should best be done by a dietician (level of evidence 3). 
3. Physical activity has a limited influence on weight loss (level of evidence 1),
   but plays an important role in the conservation of weight reduction (level of evidence 2).
4.  It is important for obese patients to build in sufficient movement in their daily live. Three times a week half an hour walking is a realistic starting point for an increase in physical activity (level of evidence 3).
5. Pharmacotherapy with orlistat or sibutramine can only work supportive, as an additive to a multidisciplinary treatment, for patients with BMI of 30 or higher or at patients with co-morbidity and with a BMI between 27 and 29.9. The expected additional impact on the weight reduction is limited, i.e. lower than 5% and this with long-term therapy (six up to 24 months) (level of evidence 1).
6. Surgery is only applied when all other less invasive treatments have failed; it should be reserved to patients with morbid obesity (BMI higher than 40) and patients with BMI higher than 35 and co-morbidity (level of evidence 3).
   After surgery, multidisciplinary support is essential for the success of the weight reduction and the detection of side effects of the procedure (level of evidence 3).