Kimberly Bombaci, MD Reviewed 06/2017

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Subject: Obesity

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  • Excess adipose tissue, typically quantified in adults by body mass index (BMI), ([kg]/[m2]), ≥30 kg/m2.

  • Obesity is associated with negative health outcomes. Abdominal obesity increases the risk of morbidity and mortality.

  • System(s) affected: endocrine/metabolic, cardiac, respiratory, gastrointestinal, musculoskeletal, dermatologic, mental health

  • Synonym(s): overweight; adiposity

Geriatric Considerations

Underweight BMI (≤18) is also associated with an increased risk of mortality. 


  • Predominant age: Incidence rises in the early 20s.

  • Predominant sex: female > male


  • 35% of U.S. adults are obese 1,2.

  • 40% of men and 25% of women are overweight.

Pediatric Considerations

  • Pediatric obesity is defined as a BMI ≥95th percentile, by age and sex specific WHO or CDC growth curves.

  • Obesity during adolescence and young adulthood is strongly associated with obesity in adulthood.


  • Obesity is caused by an imbalance between food intake, absorption, and energy expenditure.

  • Underlying organic causes include psychiatric disturbances, hypothyroidism, hypothalamic disorders, insulinoma, and Cushing syndrome.

  • Medications that contribute to obesity include corticosteroids, neuroleptics (particularly atypical antipsychotics), and antidepressants.


  • Genetic syndromes such as Prader-Willi and Bardet-Biedl are found in a minority of people with obesity.

  • Multiple genes are implicated in obesity.


  • Parental obesity

  • Sedentary lifestyle

  • Consumption of calorie-dense food

  • Low socioeconomic status

  • >2 hr/day of television viewing


  • Encourage at least 1 hour of daily exercise, limited television viewing, and moderation in portion size.

  • Avoid calorie-dense and nutrient-poor foods such as sugar-sweetened beverages and processed foods.



  • Diet and exercise habits

  • Prior attempts at weight loss

  • Reported readiness to change lifestyle

  • Social support and resources

  • Comorbidities: diabetes mellitus type 2, hypertension, hyperlipidemia, sleep apnea

  • Psychiatric history

  • Symptoms suggesting hypothyroidism, Cushing syndrome, and genetic syndromes


  • Elevated BMI:

    • ▪ Overweight: BMI = 25 to 29.9 kg/m2
    • ▪ Obese: BMI 30 to 39.9 kg/m2
    • ▪ Morbid obesity: BMI ≥40 kg/m2
  • Abdominal circumference:

    • ▪ Measure at the level of the umbilicus. Elevated:
      • * Male: >40 inches (102 cm)
      • * Female: >35 inches (88 cm)


  • Screen for underlying physiologic causes as well as associated comorbid conditions.

  • Labs should be done while fasting (nonfasting labs within normal limits are considered adequate).

  • Glucose, total insulin, hemoglobin A1C, lipids

  • Thyroid function tests

  • LFTs (fatty liver)



  • Assess:

    • ▪ Motivation to lose weight
    • ▪ Patient-specific goals of therapy
    • ▪ Need for intensive counseling to enhance adherence with diet, exercise, and behavior modification recommendations
  • Goal is to achieve and sustain loss of at least 10% of body weight.

  • Track nutritional intake and physical activity habits.

  • Use of commercial weight loss programs (e.g., Weight Watchers) can be more effective than “standard of care” counseling 3[B].

  • Behavior therapy and cognitive-behavioral methods result in modest weight loss and are most effective when combined with dietary and exercise treatments.


  • Include diet, exercise, and behavior therapy for all patients without comorbid conditions who are considering pharmacologic treatment.

  • NIH guidelines suggest at least 6 months nonpharmacologic treatment.

  • Consider medication for unsatisfactory weight loss in those with:

    • ▪ BMI ≥30
    • ▪ BMI ≥27 combined with associated risk factors (e.g., coronary artery disease, diabetes, sleep apnea, hypertension, hyperlipidemia)
  • Relapse common after medications are discontinued.

  • Treat comorbidities (such as diabetes and hyperlipidemia).

First Line

  • When compared to placebo, medications have been associated with at least 5% weight loss at 52 weeks 4[B]. Orlistat (Xenical) is a lipase inhibitor that decreases the absorption of dietary fat. Dose: 120 mg PO TID with meals containing fat; omit dose if meal is skipped or does not contain fat. Patients must avoid taking fat-soluble vitamin supplements within 2 hours of taking orlistat. The FDA has approved orlistat (Alli) 60 mg PO TID to be sold over the counter as a weight loss aid. Adverse effects mainly GI (cramps, flatus, fecal incontinence)

  • Contraindications

    • Orlistat: chronic malabsorption syndromes, cholestasis, pregnancy

Second Line

  • Appetite suppressants recommended for short-term treatment (≤6 months) 5[A]

  • Only beneficial in patients who exercise and eat reduced calorie diet

    • Naltrexone/bupropion (Contrave): 8 mg naltrexone/90 mg bupropion per tablet; slow titration up to 2 tablets PO BID by week 4; contraindicated if uncontrolled HTN, seizure disorder, chronic opioid use, pregnancy
    • Liraglutide (Saxenda): 1.203 mg SC once daily; GLP-1 agonist recently approved for obesity; discontinue if weight loss is ≪4% after 16 weeks.
    • Topiramate: Initiate with 25 mg BID and increase by 50 mg/week up to 100 mg PO BID; not FDA-approved for the treatment of obesity; tolerance is a concern (paresthesias, somnolence, difficulty concentrating).
  • Schedule IV drugs:

    • Lorcaserin (Belviq) 10 mg PO BID (D/C if weight loss is ≪5% after 12 weeks); works as serotonin agonist; avoid in those with CrCl ≪30 mL/min; contraindicated in pregnancy; avoid use with other serotonergic drugs.
    • Phentermine: 15, 30, 37.5 mg PO every morning; discontinue if tolerance or no response after 4 weeks; contraindicated if history of CV disease, hyperthyroidism, history of substance abuse, pregnancy
    • Phentermine/topiramate (3.75 to 23 mg, 7.5 to 46 mg, 11.25 to 69 mg, 15 to 92 mg); initiate 3.75 to 23 mg PO once daily; requires enrollment into Risk Evaluation and Mitigation Strategy (REMS); women of childbearing age require negative pregnancy test prior to initiation and monthly thereafter.
    • Diethylpropion: 25 mg PO before meals TID; discontinue if no response after 4 weeks; contra-indicated if severe HTN, hyperthyroidism, history of substance abuse

Pregnancy Considerations

During pregnancy, obese women should gain fewer pounds than recommended for nonobese women. 


Consider bariatric surgery if patients meet criteria. 
  • Requires complex presurgical evaluation, surgery, and follow-up in a skilled treatment center

  • Surgical procedures include biliopancreatic diversion, Roux-en-Y gastric bypass, sleeve gastrectomy, adjustable gastric banding, vagal blocking therapy (Maestro Rechargeable system), and gastric aspiration (AspireAssist).

  • Surgical treatment is the most effective long-term weight-loss treatment available for morbidly obese patients, but there is insufficient evidence on longterm outcomes 6[A].



  • Physical activity is an integral part of any weight loss program, yet physical activity alone rarely results in significant weight loss.

  • Combination of weight training and aerobic activity is preferred over aerobic activity alone.

Patient Monitoring

Long-term routine follow-up may prevent relapse after weight loss or further weight gain. 


  • Long-term studies suggest net calorie reduction (500 to 1,000 kcal/day) and ease of use are more important than the composition of the particular diet for long-term results:

    • ▪ A reduction of 500 kcal/day can result in ∽1 lb (0.45 kg) weight loss per week.
    • ▪ Portion-control is essential.
  • Very low-calorie diet (400 to 800 kcal/day)

    • ▪ Can result in more rapid weight loss than higher calorie diets but is less effective in the long term
    • ▪ Complications include dehydration, orthostatic hypotension, fatigue, muscle cramps, constipation, headache, and cold intolerance.
    • ▪ Relapse common if diet discontinued.
    • ▪ Contraindications: recent myocardial infarction or cerebrovascular accident, renal disease, cancer, pregnancy, insulin-dependent diabetes mellitus, and some psychiatric disturbances


  • Healthy diet and physical activity patterns

  • Focus on behaviors (not numbers)

  • Recommended Web site:

    • ▪ www.nal.usda.gov/fnic/foodcomp/search for the FDA nutritional content in common foods


  • Lowest mortality associated with a BMI of 22

  • Long-term maintenance of weight loss is difficult.

  • Patient motivation is associated with successful weight loss 7.


  • Cardiovascular disease

  • Stroke (in men)

  • Thromboembolism

  • Heart failure

  • Hypertension

  • Hypoventilation and sleep apnea syndromes

  • Higher death rates from cancer: colon, breast, prostate, endometrial, gallbladder, liver, kidney

  • Diabetes mellitus

  • Skin changes

  • Hyperlipidemia

  • Gallbladder disease

  • Osteoarthritis

  • Gout

  • Poor self-esteem

  • Discrimination

  • Increased sick leave


Ogden  CL, Carroll  MD, Flegal  KM. Prevalence of obesity in the United States. JAMA.  2014;312(2):189–190.  [View Abstract]
Ogden  CL, Carroll  MD, Fryar  CD, et al. Prevalence of obesity among adults and youth: United States, 2011-2014. NCHS Data Brief.  2015;(219):1–8.  [View Abstract]
Jebb  SA, Ahern  AL, Olson  AD, et al. Primary care referral to a commercial provider for weight loss treatment versus standard care: a randomised controlled trial. Lancet.  2011;378(9801):1485–1492.  [View Abstract]
Khera  R, Hassan Murad  M, Chandar  A, et al. Association of pharmacological treatments for obesity with weight loss and adverse events: a systematic review and meta-analysis. JAMA.  2016;315(22):2424–2434.  [View Abstract]
Dombrowski  SU, Knittle  K, Avenell  A, et al. Long term maintenance of weight loss with non-surgical interventions in obese adults: systematic review and meta-analyses of randomised controlled trials. BMJ.  2014;348:g2646. doi:10.1136/bmj.g2646.  [View Abstract]
Puzziferri  N, Roshek TB  , III, Mayo  HG, et al. Long-term follow-up after bariatric surgery: a systematic review. JAMA.  2014;312(9):934–942.  [View Abstract]
Ogden  LG, Stroebele  N, Wyatt  HR, et al. Cluster analysis of the national weight control registry to identify distinct subgroups maintaining successful weight loss. Obesity (Silver Spring).  2012;20(10):2039–2047.  [View Abstract]



  • E66.9 Obesity, unspecified

  • E66.3 Overweight

  • R63.5 Abnormal weight gain

  • E66.8 Other obesity

  • E66.09 Other obesity due to excess calories

  • E66.01 Morbid (severe) obesity due to excess calories


  • 278.00 Obesity, unspecified

  • 278.02 Overweight

  • 783.1 Abnormal weight gain

  • 278.01 Morbid obesity


  • 414916001 obesity (disorder)

  • 238131007 overweight (finding)

  • 161833006 abnormal weight gain (finding)

  • 450451007 Overweight in childhood (finding)

  • 238136002 Morbid obesity (disorder)


  • A majority of American adults are overweight or obese.

  • Modification in dietary and physical activity patterns remain the cornerstone of therapy for obesity. Consider bariatric surgery in patients with a BMI >40 who have failed more conservative treatment, particularly if there are associated risk factors.

  • Medication may be indicated when nonpharmacologic treatment for 6 months has been ineffective and the patient has a BMI >30 or a BMI >27 with associated risk factors.