Obesity and Weight Management
Manual of Clinical Nutrition Management III- 86 Copyright © 2013 Compass Group, Inc.
randomized trials found VLCDs to be no more effective than low-energy diets 1 year after treatment, leading the
National Institutes of Health Expert Committee to not recommend VLCDs (4).
Meal replacements: Meal replacements are growing in popularity as another category of energy-controlled diets
(6). A meal is replaced with a liquid drink that contains approximately 200 kcal per serving and approximately 50%
to 60% carbohydrate, 30% protein, and 10% fat, or a pre-measured frozen meal of a set energy value (6). The meal
replacement helps the patient control energy intake and reduces sensory stimulation and the need to make
decisions about portion size (6). Weight loss outcomes using a meal replacement are dependent on the patient’s
adherence to the meal plan. Studies demonstrate sustained weight loss of 3.2% to 8.4% over 4 years using meal
replacements (28,29). For people who have difficulty with self-selection or portion control, meal replacements (eg,
liquid meals, meal bars, energy-controlled packaged meals) may be used as part of the diet component of a
comprehensive weight management program. Substituting one or two daily meals or snacks with meal
replacements is a successful weight loss and weight maintenance strategy (Grade I) (6,7).
Pharmacotherapy: Pharmacologic agents for obesity intervention contribute to energy deficit through a
variety of mechanisms (27). There are currently few pharmacotherapy options available for long-term use (6).
Medications approved by the Food and Drug Administration for the treatment of significant clinical obesity
include sibutramine (Meridia) and orlistat (Xenical) (6). The greatest benefit of pharmacotherapy may be the
facilitation of weight loss maintenance, rather than the induction of weight loss (29,30). Two-year studies of
sibutramine and orlistat showed that participants who remained on medication at the end of this time
maintained weight losses that were nearly twice as great as those of participants who received placebo (30). It
may be recommended that these medications be used long-term in the same manner as agents for
hypertension, hyperlipidemia, and diabetes mellitus (31). Criteria for pharmacotherapy intervention include a
BMI of at least 30 kg/m^2 with no comorbid conditions, or a BMI of at least 27 kg/m^2 with comorbid conditions
or a very high health risk (4). Research indicates that pharmacotherapy may enhance weight loss in some
overweight and obese adults (Grade I) (6,7).
Sibutramine is a combined centrally acting serotonin-norepinephrine reuptake inhibitor that is associated
with increased satiation. Sibutramine seems to reduce body weight by modifying intake through increased
satiety, and animal data suggest that it may also increase energy expenditure by stimulating thermogenesis
(31). When combined with a low-energy diet, 10 to 15 mg/day of sibutramine produces a clinically significant
greater loss of initial weight (7%) when compared to a low-energy diet plus placebo (32). Weight loss of 10%
to 15% has been observed in studies that combine sibutramine with intensive lifestyle modification (33,34).
Sibutramine is not recommended for patients with uncontrolled hypertension or a history of coronary artery
disease, arrhythmias, heart failure, or stroke. In addition, some antidepressants, such as monoamine oxidase
inhibitors or selective serotonin reuptake inhibitors, may counteract with the mechanism of sibutramine;
therefore, it is not recommended that these medications be taken concurrently (31). Complications of
sibutramine include dry mouth, nausea, headache, insomnia, increased blood pressure, and increased heart
rate (4,6,29).
Amphetamine-like derivatives, such as phentermine and phentermine resin (Adipex-P, Fastin, and others),
mazindol, benzphetamine, and phendimetrazine, which are frequently approved and prescribed for short-
term use (< 3 months), have a different mechanism of action other pharmological medications. They
decrease appetite and food intake by increasing the availability of norepinephrine in the brain. The
complications of these drugs are similar to those of sibutramine. Fenfluramine (Pondimin) and
dexfenfluramine (Redux) were voluntarily withdrawn from the market because of reports of their association
with valvular heart disease. They are serotoninergic agents that act primarily by increasing serotonin levels
in the brain, leading to a decrease in appetite (6). Herbal preparations for weight loss do not have
standardized amounts of active ingredients and have been reported to have harmful effects (6). Certain over-
the-counter preparations containing phenylpropanolamine (eg, Dexatrim) and related compounds have no
proven efficacy and have been recalled because of reported incidences of hemorrhagic stroke (6).
Orlistat, a pancreatic lipase inhibitor, is the first obesity medication that does not act systemically. Orlistat
inhibits the absorption of up to 30% of dietary fat contained in a meal, leading to a loss of 150 to 180 kcal/day
(35). Patients should take this medication with meals, as it takes effect within 2 hours of ingestion. Patients
receiving orlistat should follow a moderately low-fat diet (less than 30% of total energy from fat), with fat
distributed evenly at each meal. Consumption of more than 20 g of fat per meal or 70 g of fat per day can
induce adverse gastrointestinal events that include flatus, oily leakage or oily stools, and diarrhea (6).
Supplementation with fat-soluble vitamins may be needed (6). In randomized trials, participants who
received placebo plus diet lost 6% of their weight in 1 year, compared with a 10% weight loss for those