Obesity

Kimberly Bombaci, MD Reviewed 06/2017
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Subject: Obesity

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BASICS

DESCRIPTION

  • 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. 

EPIDEMIOLOGY

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

  • Predominant sex: female > male

Prevalence

  • 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.

ETIOLOGY AND PATHOPHYSIOLOGY

  • 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.

Genetics

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

  • Multiple genes are implicated in obesity.

RISK FACTORS

  • Parental obesity

  • Sedentary lifestyle

  • Consumption of calorie-dense food

  • Low socioeconomic status

  • >2 hr/day of television viewing

GENERAL PREVENTION

  • 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.

DIAGNOSIS

HISTORY

  • 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

PHYSICAL EXAM

  • 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)

DIAGNOSTIC TESTS & INTERPRETATION

  • 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)

TREATMENT

GENERAL MEASURES

  • 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.

MEDICATION

  • 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. 

SURGERY/OTHER PROCEDURES

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].

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

  • 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. 

DIET

  • 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

PATIENT EDUCATION

  • 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

PROGNOSIS

  • 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.

COMPLICATIONS

  • 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

REFERENCES

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]

CODES

ICD10

  • 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

ICD9

  • 278.00 Obesity, unspecified

  • 278.02 Overweight

  • 783.1 Abnormal weight gain

  • 278.01 Morbid obesity

SNOMED

  • 414916001 obesity (disorder)

  • 238131007 overweight (finding)

  • 161833006 abnormal weight gain (finding)

  • 450451007 Overweight in childhood (finding)

  • 238136002 Morbid obesity (disorder)

CLINICAL PEARLS

  • 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.

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