Applied Evidence

Effective management of obesity

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References

TABLE 1
Body mass index (BMI) and degrees of obesity

BMICategoryTherapeutic options
<18.5Underweight
18.5–25.9Normal weightReinforce positive lifestyle
25.0–29.9OverweightDiet, exercise, behavior modification
30.0–34.9Obese (Class I)Diet, exercise, behavior modification; consider pharmacologic therapy*
35.0–39.9Obese (Class II)Diet, exercise, behavior modification; consider pharmacologic therapy
≥40.0Obese (Class III or “Morbid Obesity”)Consider surgical management
*For patients with multiple cardiovascular risk factors (eg, diabetes, hyperlipidemia), BMI >27 may be an indication for pharmacologic intervention at; at BMI >37, patients may be considered candidates for surgical therapy.
From the National Institutes of Health. Clinical guidelines on the identification, evaluation, and treatment of obesity in adults: the Evidence Report. Bethesda, Md: US Department of Health and Human Services, 1998.

Evaluation of documented obesity

In history taking and physical examination, look for reversible causes of obesity (including medications and endocrine disorders), consider the degree of obesity, and determine whether comorbid conditions are present, to help estimate prognosis. Evaluate the patient’s dietary and exercise habits, as well as willingness to modify these habits if necessary.1,5 Finally, review the patient’s weight history and any attempts at weight loss.

Medications associated with weight gain include psychotropic drugs, anticonvulsant agents, steroid hormones, insulin, and many oral hypoglycemic agents.1

Endocrine disorders such as Cushing’s syndrome and hypothyroidism may also contribute to obesity, but only rarely. Physical findings that increase the likelihood of Cushing’s syndrome, and their respective positive likelihood ratios (LR+)— the higher the value, the greater the likelihood of disease—include: hypertension (2.3), moon facies (1.6), thin skinfold (115.6), ecchymoses (4.5), and acne (2.2).19 Findings, and their likelihood ratios, associated with hypothyroidism include coarse skin (5.6), cool/dry skin (4.7), bradycardia (4.1), enlarged thyroid (2.8), and hoarse voice (5.4).19 The very high LR for skinfold thickness was determined for women of childbearing age who had elevated risk of having Cushing’s syndrome because of a history of both menstrual irregularities and hirsutism. Skinfold thickness is determined by using calipers on an area of minimal subcutaneous fat (eg, back of the hand). For women of reproductive age, skinfold thickness is normally greater than 1.8 mm.19

Laboratory assessment of the obese patient will rarely find a cause of weight gain (eg, hypothyroidism), but the addition of selected diagnostic tests will aid in the determination of prognosis. An abnormal fasting glucose level or impaired glucose tolerance is a major risk factor for cardiovascular disease. Abnormal lipid profiles heighten that risk for obese patients. All patients with documented obesity should undergo assessment for abnormal lipids and impaired glucose tolerance5 (SOR: D).

Treatment

The most important step in treating obesity is to establish a calorie deficit. The deficit can be achieved by increasing energy expenditure or by reducing energy intake or absorption. On average, a caloric deficit of 500 kilocalories per day will result in a weight loss of 1 pound per week.5 Reasonable expectations of therapy include weight loss of 1–2 pounds a week and a loss of 10% of total body weight in 5 months.5

Interventions for weight loss fall into 4 categories: lifestyle modifications (diet, exercise, and behavioral modification), drug therapy, complementary or alternative measures, and surgery. Table 3 summarizes the levels of evidence to support each intervention.

TABLE 3
Efficacy of weight-loss interventions

Weight loss
SOR*InterventionShort-termLong-termComments
Diet, exercise, and behavioral modification
ALow/very-lowcalorie diet8% average weight loss from 3–12 monthsWeight nears baseline in studies >24 monthsVery-low-calorie diets may require laboratory assessment of metabolic function
High rate of noncompliance
ALow/very low fat with reduced caloriesSimilar to lowcalorie with moderate fatWeight nears baseline in studies >24 monthsNo known side effects
AExerciseLess weight loss than diet therapyLikely no significant weight lossImproved cardiovascular fitness
May be effective in preventing weight gain
ALow-calorie diet + exerciseIncreased weight loss vs. diet or exercise aloneWeight nears baseline in long-term studiesImproved cardiovascular fitness
Compliance a major problem
BBehavior modificationIncreases effectiveness of diet, exerciseNo significant effect at 5 yearsNo reported harms
Only studied when used with other methods
CLowcarbohydrate dietNot significant if calories are not reducedNo long-term data availableNo known side effects, but creates nutritional imbalance and ketosis
Needs additional study
Medication
ASibutramine˜ 4 kg for trials less than 1 yearModest weight loss when used for >1 yearCan elevate blood pressure
Number needed to treat (NNT) for 5% weight loss at 1 year = 3
NNT for 10% weight loss at 1 year = 5
AOrlistat˜ 2–3 kg for trials less than 1 year˜ 3 kg at 2 yearsGI side effects common, possible vitamin deficiencies
NNT for 5% weight loss at 1 year = 5
NNT for 10% weight loss at 1 year = 7
Surgery
BRoux-en-Y Gastric bypass˜ 50 kg (110 lbs) at 1 year˜ 50 kg (110 lbs) at up to 4 yearsSignificant operative risk and post-operative GI side effects
Nadir for weight loss occurs at 12–24 months
BGastric banding˜ 30 Kg (66 lbs) at one year10–15% of initial weight lost may be regained long-termSignificant operative risk and post-operative GI side effects
Generally considered less effective that gastric bypass
Complementary/alternative medicine
BHypnosisMinimal reductionNo statistically significant differenceStudied in combination with cognitive behavioral therapy
Systematic reviews reveal significant heterogeneity of low-quality randomized controlled trials
BAcupunctureNo significant differenceNo significant differenceSystematic review reveals poor quality
RCTs, which limits ability to determine effect
* Strength of recommendation
A = Systematic review of randomized controlled trials (RCT) (with homogeneity) or individual RCT with narrow confidence interval
B = Systematic review of cohort studies (with homogeneity), individual cohort studies or low-quality RCT, individual case-control study or SR of case-control studies (with homogeneity)
C = Case series and poor quality cohort and case control studies

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