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.
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.
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
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
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