Obesity is associated with the development of several diseases

check the body mass index (BMI)

Obesity (BMI > 27) is a highly prevalent condition that affects 35% of men and 27% of women in Canada, while morbid obesity (BMI > 35) is found in 2% of men and 4% of women.

Obesity is associated with the development of several diseases, including hypertension, diabetes mellitus, hyperlipidemia, coronary artery disease, obstructive sleep apnea, and cancers of the breast, uterus, prostate and colon.

It is also associated with psychological disorders, including depression, anorexia nervosa and bulimia, and is an independent risk factor for increased mortality.

In adults with obesity (BMI greater than 27) management options include weight reduction, prevention of further weight gain or no intervention. The long-term (more than 2 years) effectiveness of (a) methods to prevent obesity and (b) methods to treat obesity.

Experts in family medicine, internal medicine, pediatrics, psychiatry, surgery and epidemiology used an evidence-based method for evaluating the effectiveness of preventive health care interventions. Recommendations were not based on cost-effectiveness of options. Patient preferences were not discussed.

Background papers providing critical appraisal of the evidence and tentative recommendations prepared by the chapter author were pre-circulated to the members. Evidence for this topic was presented and deliberated upon in several 1- to 2-day meetings in 1994.

An update of the review was completed in 1997 and reviewed by the Task Force via in January and June 1997. Consensus was reached on recommendations, which were finalized in June 1998.

Benefits, Harms, and Costs

Studies investigating the effect of dietary therapy on obesity often find initial weight reductions which are followed by gradual weight regain. Very-low-calorie diets have been associated with fatigue, dizziness, hair loss, menstrual irregularities, cholelithiasis, gouty arthritis and cardiac arrhythmias.

A similar reduction-regain pattern is observed with anoretic drug therapy, with effective weight loss during the first six months of treatment, while the effectiveness beyond 1 year has only been shown in a small proportion of patients from a single study.

Anorectic drug therapy is associated with drowsiness, fatigue, nausea, diarrhea, urinary retention, dry mouth and a small but clinically important increased risk of pulmonary hypertension and valvular heart disease. Long-term success has been reported in a number of studies investigating weight-reduction surgery.

Postoperative morbidity occurred in less than 5% of patients in the studies reviewed, with re-operative rates reported from 1.7% to 7.1% in 3 studies and 20.3% to 33.3% in 2 others. Long-term dietary counselling has been shown to be successful in a small proportion of patients who achieved sustainable moderate weight-loss.

Also, weight-reduction interventions are associated with an increased risk of major depression, bulimia and other eating disorders. Despite earlier concerns about the risks associated with repeated episodes of weight loss and weight regain (weight cycling), recent reviews have found that weight cycling is not associated with increased mortality.