MKSAP Quiz: dietary counseling for class II obesity
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A 56-year-old woman is evaluated during a routine annual visit. The patient would like to lose weight. She works as a teacher and is physically active, walking briskly 2 or 3 times a week for 20 or 30 minutes. She does not smoke and drinks alcohol only on occasion. Her medical history includes hypertension and hyperlipidemia, both well controlled with medications.
On physical examination, the blood pressure is 135/88 mm Hg. The BMI is 36. The remainder of the physical examination is normal. Laboratory studies include a fasting plasma glucose level of 105 mg/dL (5.83 mmol/L) and a serum thyroid-stimulating hormone level of 2.5 µU/mL (2.5 mU/L). A diagnosis of class II obesity is established. A goal is set for a 5% to 15% reduction in weight.
Which of the following diets should be advised for this patient?
A. A balanced low-calorie diet (1,200 to 1,500 Kcal/day)
B. A very-low-calorie diet (<1,000 Kcal/day)
C. A reduced-fat diet (fat constitutes <30% of total caloric intake/day)
D. A low-carbohydrate diet (<35 g of carbohydrates/day)
MKSAP Answer and Critique
The correct answer is A) A balanced low-calorie diet (1,200 to 1,500 Kcal/day). This item is available online to MKSAP 14 subscribers in the General Internal Medicine section, Item 57.
The standard of weight loss against which dietary interventions are compared is counseling for exercise and a balanced low-calorie diet. Against this standard, very-low-calorie diets are more difficult to adhere to and have not been found more effective at 1 year. Low-fat and low-carbohydrate diets have limited evidence to support their long-term efficacy. Low-carbohydrate diets, in particular, have not been well evaluated in persons older than 53 years of age and/or those with comorbid conditions. There is evidence from randomized, controlled trials that participation in Weight Watchers' proprietary program leads to a loss of 3.2% of initial weight at 2 years. The Weight Watchers program recommends a balanced low-calorie diet, exercise, and behavioral modification.
Obesity is defined by the World Health Organization (WHO) as patients who have a BMI of 30 or higher. This patient has class II obesity. There are three classes of obesity; class I is associated with a BMI of 30 to 34.9, class II with a BMI of 35 to 39.9, and class III with a BMI of 40 or greater. The WHO has defined success in management of the obese patient as a 5% to 15% reduction in initial weight. This patient has several risk factors for cardiovascular disease including obesity, hypertension, and hyperlipidemia. Obesity is also a risk factor for breast cancer among postmenopausal women. Therefore, weight reduction is an important intervention with respect to risk factor modification in this patient.
Key Point
- The standard of weight loss against which dietary interventions are compared is counseling for exercise and a balanced low-calorie diet.