Tuesday, April 23, 2024


Practice Essentials

Obesity is a substantial public health crisis in the United States, and internationally, with the prevalence increasing rapidly in numerous industrialized nations.
A report from the National Center for Health Statistics stated that in US individuals aged 20 years or older, the prevalence of obesity rose steadily from 19.4% in 1997 to 31.4% for the period January-September 2017.

The image below details the comorbidities of obesity.

Comorbidities of obesity.

Comorbidities of obesity.

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Signs and symptoms

Although several classifications and definitions for degrees of obesity are accepted, the most widely accepted classifications are those from the World Health Organization (WHO), based on body mass index (BMI). The WHO designations are as follows:

Grade 1 overweight (commonly and simply called overweight) – BMI of 25-29.9 kg/m2

Grade 2 overweight (commonly called obesity) – BMI of 30-39.9 kg/m2

Grade 3 overweight (commonly called severe or morbid obesity) – BMI ≥40 kg/m2

Some authorities advocate a definition of obesity based on percentage of body fat, as follows:

Men: Percentage of body fat greater than 25%, with 21-25% being borderline

Women: Percentage of body fat great than 33%, with 31-33% being borderline

The clinician should also determine whether the patient has had any of the comorbidities related to obesity, including the following

Respiratory: Obstructive sleep apnea,
greater predisposition to respiratory infections, increased incidence of bronchial asthma, and Pickwickian syndrome (obesity hypoventilation syndrome

Malignant: Reported association with endometrial (premenopausal), prostate, colon (in men), rectal (in men), breast (postmenopausal), gall bladder, gastric cardial, biliary tract system, pancreatic, ovarian, renal, and possibly lung cancer, as well as with esophageal adenocarcinoma and multiple myeloma

Psychological: Social stigmatization and depression

Cardiovascular: Coronary artery disease,
essential hypertension, left ventricular hypertrophy, cor pulmonale, obesity-associated cardiomyopathy, accelerated atherosclerosis, and pulmonary hypertension of obesity

Central nervous system (CNS): Stroke, idiopathic intracranial hypertension, and meralgia paresthetica

Obstetric and perinatal: Pregnancy-related hypertension, fetal macrosomia, and pelvic dystocia

Surgical: Increased surgical risk and postoperative complications, including wound infection, postoperative pneumonia, deep venous thrombosis, and pulmonary embolism

Pelvic: Stress incontinence

Gastrointestinal (GI): Gall bladder disease (cholecystitis, cholelithiasis), nonalcoholic steatohepatitis (NASH), fatty liver infiltration, and reflux esophagitis

Orthopedic: Osteoarthritis, coxa vera, slipped capital femoral epiphyses, Blount disease and Legg-Calvé-Perthes disease, and chronic lumbago

Metabolic: Type 2 diabetes mellitus, prediabetes, metabolic syndrome, and dyslipidemia

Reproductive (in women): Anovulation, early puberty, infertility, hyperandrogenism, and polycystic ovaries

Reproductive (in men): Hypogonadotropic hypogonadism

Cutaneous: Intertrigo (bacterial and/or fungal), acanthosis nigricans, hirsutism, and increased risk for cellulitis and carbuncles

Extremity: Venous varicosities, lower extremity venous and/or lymphatic edema

Miscellaneous: Reduced mobility and difficulty maintaining personal hygiene

See Clinical Presentation for more detail.


Laboratory studies

Fasting lipid panel

Liver function studies

Thyroid function tests

Fasting glucose and hemoglobin A1c (HbA1c)

Evaluation of degree of body fat

BMI calculation, waist circumference, and waist/hip ratio are the common measures of the degree of body fat used in routine clinical practice. Other procedures that are used in few clinical centers include the following:

Caliper-derived measurements of skin-fold thickness

Dual-energy radiographic absorptiometry (DEXA)

Bioelectrical impedance analysis

Ultrasonography to determine fat thickness

Underwater weighing

See Workup for more detail.


Treatment of obesity starts with comprehensive lifestyle management (ie, diet, physical activity, behavior modification).
The 3 major phases of any successful weight-loss program are as follows:

Preinclusion screening phase

Weight-loss phase

Maintenance phase – This can conceivably last for the rest of the patient’s life but ideally lasts for at least 1 year after the weight-loss program has been completed


Currently, the 3 major groups of drugs used to manage obesity are as follows:

Centrally acting medications that impair dietary intake

Medications that act peripherally to impair dietary absorption

Medications that increase energy expenditure

Setmelanotide is the first drug approved for weight management in patients with rare genetic conditions (ie, proopiomelanocortin [POMC], proprotein convertase subtilisin/kexin type 1 [PCSK1], leptin receptor [LEPR] deficiencies). 

Two glucagonlike peptide-1 (GLP-1) agonists (liraglutide, semaglutide) have been approved by the US Food and Drug Administration (FDA) for chronic weight management.


Among the standard bariatric procedures are the following:

Roux-en-Y gastric bypass

Adjustable gastric banding

Gastric sleeve surgery

Vertical sleeve gastrectomy

Horizontal gastroplasty

Vertical-banded gastroplasty

Duodenal-switch procedures

Biliopancreatic bypass

Biliopancreatic diversion

See Treatment and Medication for more detail.

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