Obesity in Adults

Background

• Obesity is most often defined as a body mass index (BMI) ≥ 30 kg/m², although lower BMI screening cutoffs have been recommended in adults of South Asian, Southeast Asian, or East Asian ethnicity.
• Obesity is often subclassified as:
  • class 1 obesity is BMI 30-34.9 kg/m² (mild)
  • class 2 obesity is BMI 35-39.9 kg/m² (moderate)
  • class 3 obesity is BMI ≥ 40 kg/m² (severe)
  • "super obesity" is BMI ≥ 50 kg/m²
• Risk factors for obesity include:
  • lower socioeconomic status in developed countries
  • genetic predisposition
  • consumption of a highly processed diet and added sugar
  • obesogenic social network
  • physical inactivity
  • stress
  • depression, some eating disorders, and some other psychiatric conditions
  • tobacco cessation
  • disordered or insufficient sleep
  • medications
  • childhood obesity
  • pregnancy
  • changes in gut microbiota
  • age-related changes (including menopause and loss of lean body mass)
  • weight bias and stigma
• Obesity is associated with increased morbidity and mortality, including increased risk of cardiovascular events and increased risk of certain cancers.
• A positive energy balance (increased energy intake and/or decreased energy expenditure in relation to each other) of 50-60 calories/day sustained over a year may lead to an increase weight of > 5.3 lbs (2.4 kg).

Evaluation

• Screen all patients ≥ 18 years old for obesity and offer intensive counseling and behavioral interventions to patients with body mass index (BMI) ≥ 30 kg/m² (Strong recommendation).
• Ask about heredity/development, sleep, diet/activity, economic factors, social support, emotional/binge eating, and medications, which may all be secondary causes of weight gain and can all impact the decision to look for complications.
• Body mass index should be measured for assessment of obesity classification, but does not directly measure adiposity. The implications of BMI are less clear in muscular and sarcopenic patients.
• In patients with a BMI < 35 kg/m², the addition of waist circumference (measured at the iliac crest of the pelvis) should be considered for obesity risk classification with:
  • low risk defined as a waist circumference < 37 inches (94 cm) for men, < 31.5 inches (80 cm) for women
  • high risk defined as a waist circumference ≥ 37 inches (94 cm) for men, ≥ 31.5 inches (80 cm) for women
  • very high risk defined as a waist circumference ≥ 40.2 inches (102 cm) for men, ≥ 34.6 inches (88 cm) for women
  • high risk of complications for adults of South and/or East Asian ancestry is considered a waist circumference ≥ 33.5 inches (85 cm) for men, ≥ 29.1-31.5 inches (74-80cm) for women
• Tests that may be useful for identifying complications of obesity or associated conditions include a fasting glucose, glucose tolerance test, or HbA1C, lipid panel, liver enzymes, complete blood count, and thyroid-stimulating hormone.
• Blood pressure should also be assessed to evaluate for associated hypertension.

Management

• Diet and exercise are the first-line methods for weight loss.
  • Different dietary approaches are effective for weight loss and weight maintenance as long as target calorie reduction is achieved; consider specific types of diet or dietary patterns to optimize adherence, eating patterns, metabolic profiles, risk factor reduction, and/or other clinical outcomes. Recommended options for achieving calorie restriction include:
    • energy deficit of 500-750 calories below estimated energy needs (recommended for patients with obesity by American Association of Clinical Endocrinologists/American College of Endocrinology)
    • consumption of 1,200-1,500 calories/day for women or 1,500-1,800 calories/day for men (calories adjusted for individual's body weight [recommended for patients with obesity by the American Heart Association, American College of Cardiology, and The Obesity Society])
    • adherence to restrictive diet (such as low-carbohydrate, low-fat, high-fiber or meal replacement diets) to create energy deficit through reduced food intake
  • Moderate-intensity exercise is recommended for adults with obesity (Strong recommendation). More than 150 minutes/week is generally needed to show any weight loss. Exercise may be even more helpful for maintenance than for induction of weight loss.
• Use medications as part of a comprehensive weight loss program that includes behavior therapy, diet, and physical activity. Weight loss medications may be useful for patients with body mass index (BMI) ≥ 27 kg/m² with concomitant obesity-related risk factors or diseases (diabetes, hypertension, or dyslipidemia), or those with BMI ≥ 30 kg/m². When added to intensive behavioral therapy, medications can significantly increase weight loss. Medications FDA approved for chronic management (> 6 months) of weight loss include:
  • orlistat (Xenical) 120 mg orally 3 times daily
  • liraglutide (Saxenda) 3 mg subcutaneously once daily (after 4-week escalation, starting with 0.6 mg once daily and followed by weekly increases of 0.6 mg [0.6, 1.2, 1.8, 2.4, 3] until maintenance dosage of 3 mg once daily)
  • phentermine/topiramate extended release (Qsymia) 7.5 mg/46 mg orally once daily
  • naltrexone/bupropion extended release (Contrave), initially 8 mg/90 mg orally once daily, may be increased over several weeks to 16 mg/180 mg orally twice daily
• Patients with obesity should participate in a comprehensive behavioral intervention that is high-intensity (≥ 14 sessions over 6 months), on-site, and delivered by a trained professional in a group or individual setting (Strong recommendation).
• Patients with obesity should be offered at least monthly contact for maintenance of weight loss after the end of the initial program (Strong recommendation).
• Bariatric surgery may be appropriate for patients with
  • BMI ≥ 40 kg/m² without coexisting medical problems and without excessive surgical risk (Strong recommendation)
  • BMI ≥ 35 kg/m² with ≥ 1 severe obesity-related comorbidity (Strong recommendation)
  • BMI ≥ 30 kg/m² with ≥ 1 severe obesity-related comorbidity or type 2 diabetes (Weak recommendation)
• Compared with nonsurgical management, bariatric surgery may be associated with reduced mortality, better long-term weight loss (maintained up to 10 years), higher reductions in obesity-related conditions such as diabetes, hyperlipidemia, hypertension, and obstructive sleep apnea, and improved fertility in women.
• A 5%-15% weight loss may greatly reduce complications and improve metabolic parameters in persons with overweight or obesity. Some complications require more weight loss than others for improvement.