974  American Family Physician www.aafp.org/afp Volume 82, Number 8 ◆ October 15, 2010

Aboutonethirdof theU.S.populationandone fourth of the population in the UnitedKingdom are obese, with increased risk ofhypertension, dyslipidemia, diabetes mel-litus, cardiovascular disease, osteoarthritis,andsomecancers.

•Fewerthan10percentofoverweightorobeseadults40to49yearsofagereverttoanormalbodyweightafterfouryears.

• Nearly 5 million U.S. adults used pre-scription weight-loss medication between1996 and 1998, but one fourth of all userswerenotoverweight.

Orlistat, phentermine, rimonabant, andsibutramine may promote modest weightloss(anadditional2.22to15.56lbs[1to7kg]lost)comparedwithplaceboinobeseadultsundergoing lifestyle interventions,but thesemedicationscancauseadverseeffects.

• Sibutramine may be more effective atpromoting weight loss compared with orli-stat,althoughnotinobesepersonswithtype2diabetesorhypertension.

• We do not know whether combina-tiontreatmentwithorlistatandsibutramineleadstogreaterweightlossthaneithertreat-mentalone.

•Wedonotknowwhetherdiethylpropionand mazindol are effective at promotingweightlossinpersonswithobesity.

•Orlistathasbeenassociatedwithgastro-intestinaladverseeffects.

• Phentermine has been associated withheartandlungproblems.

• Sibutramine has been associated withcardiac arrhythmias and cardiac arrest.In January 2010, the European MedicinesAgency suspendedmarketingauthorization

Obesity in AdultsDAVIDDELAET,Mount Sinai School of Medicine, New York, New York

DANIELSCHAUER,Institute for the Study of Health, Cincinnati, Ohio

This is one in a series of chapters excerpted from the Clinical Evidence Handbook, published by the BMJ Publishing Group, London, U.K. The medical information contained herein is the most accurate available at the date of publication. More updated and comprehensive infor-mation on this topic may be available in future print editions of the Clinical Evidence Handbook, as well as online at http://www.clinicalevidence.bmj.com (subscription required). Those who receive a complimentary print copy of the Clinical Evidence Handbook from United Health Foundation can gain complimentary online access by register-ing on the Web site using the ISBN number of their book.

This clinical content con-forms to AAFP criteria for evidence-based continuing medical education (EB CME). See CME Quiz on page 887.

A collection of Clinical Evidence Handbook pub-lished in AFP is available at http://www.aafp.org/afp/bmj.

Clinical Questions

What are the effects of drug treatments in adults with obesity?

Trade-off between benefits and harms

Orlistat

Phentermine

Rimonabant

Sibutramine

Unknown effectiveness Diethylpropion

Mazindol

Sibutramine plus orlistat (insufficient evidence to assess combination versus either intervention alone)

What are the effects of bariatric surgery in adults with morbid obesity?

Likely to be beneficial Bariatric surgery (more effective than nonsurgical treatment for clinically important weight loss in morbidly obese adults, but operative complications are common)

Biliopancreatic diversion

Gastric banding

Gastric bypass

Vertical banded gastroplasty

Unknown effectiveness Sleeve gastrectomy

Clinical Evidence HandbookA Publication of BMJ Publishing Group

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Clinical Evidence Handbook

October 15, 2010 ◆ Volume 82, Number 8 www.aafp.org/afp American Family Physician  975

of sibutramine in the European Union because of theincreased risk of nonfatal myocardial infarctions andstrokes.

•Rimonabanthasbeenassociatedwithanincreasedriskofpsychiatricdisorders.

Bariatricsurgery(gastricbypass,verticalbandedgas-troplasty,biliopancreaticdiversion,orgastricbanding)may increase weight loss compared with no surgery inpersonswithmorbidobesity.

Comparedwitheachother,wedonotknowwhethergastric bypass, vertical banded gastroplasty, biliopan-creaticdiversion,orgastricbandingisthemosteffectivesurgeryortheleastharmful.

• We do not know whether sleeve gastrectomy iseffective.

•Bariatricsurgerymayresultinalossofgreaterthan20 percent body weight, which may be largely main-tainedfor10years.

•Operativeandpostoperativecomplicationsarecom-monand,onaverage,0.28percentofpatientsdiewithin30daysofsurgery.Mortalitymaybeashighas2percentin some high-risk populations. However, surgery mayreducelong-termmortalitycomparedwithnosurgery.

DefinitionObesityisachronicconditioncharacterizedbyanexcessof body fat. It is most often defined by the body massindex(BMI),amathematicalformulathatishighlycor-relatedwithbodyfat.BMIisweightinkilogramsdividedby height in meters squared (kg per m2). Worldwide,adultswithaBMIof25to30kgperm2arecategorizedasoverweight,andthosewithaBMIgreaterthan30kgperm2arecategorizedasobese.

Nearly5millionU.S.adultsusedprescriptionweight-lossmedicationbetween1996and1998.Onefourthofusers were not overweight. Inappropriate use of pre-scriptionmedicationismorecommoninwomen,whitepersons,andHispanicpersons.TheNationalInstitutesofHealthissuedguidelinesforobesitytreatment,whichindicate that all obese adults (BMI greater than 30 kgperm2)andalladultswithaBMIofatleast27kgperm2and obesity-associated chronic diseases are candidatesfordrugtreatment.Morbidlyobeseadults(BMIgreaterthan40kgperm2)andalladultswithaBMIofatleast35kgperm2andobesity-associatedchronicdiseasesarecandidatesforbariatricsurgery.

Incidence and PrevalenceObesity has increased steadily in many countries since1900. In theUnitedKingdomin2002, itwasestimated

that 23 percent of men and 25 percent of women wereobese. The prevalence of obesity in the United Statesincreased from22.9percentbetween1988and1994, to34percentin2006.

EtiologyObesity is theresultof long-termmismatches inenergybalance,inwhichdailyenergyintakeexceedsdailyenergyexpenditure.Energybalanceismodulatedbymanyfac-tors,includingmetabolicrate,appetite,diet,andphysicalactivity.Althoughthesefactorsareinfluencedbygenetictraits, the increase inobesityprevalence in thepast fewdecades cannot be explained by changes in the humangene pool, and it is more often attributed to environ-mental changes thatpromoteexcessive food intakeanddiscouragephysicalactivity.Lesscommonly,obesitymaybe induced by drugs (e.g., high-dose glucocorticoids,antipsychotics,antidepressants,oralhypoglycemics,anti-epileptics) or be secondary to various neuroendocrinedisorders, such as Cushing syndrome and polycysticovarysyndrome.

PrognosisObesityisariskfactorforseveralchronicdiseases,includ-ing hypertension, dyslipidemia, diabetes, cardiovasculardisease, sleep apnea, osteoarthritis, and some cancers.The relationship between increasing body weight andmortality iscurvilinear, inwhichmortality ishighest inadultswithverylowbodyweights(BMIlessthan18.5kgper m2) and in adults with the highest body weights(BMIgreaterthan35kgperm2).Obeseadultshavemoreannual admissions to hospitals, more outpatient visits,higherprescriptiondrugcosts,andworsehealth-relatedqualityoflifethanthosewithnormalweight.Fewerthan10percentofoverweightorobeseadults40to49yearsofagereverttoanormalbodyweightafterfouryears.

EDITOR’S NOTE: Mazindol and rimonabant are not available in the United States.

SEARCH DATE: May 2009

Author disclosure: Nothing to disclose.

Adapted with permission from DeLaet D, Schauer D. Obesity in adults. Clin Evid Handbook. June 2010:216-217. Please visit http://www.clinicalevidence.bmj.com for full text and references. ■