- Multiple factors contribute to the development of obesity and its consequences.
- Environment, genetics and epigenetic influences all influence the condition.
- Environmental elements include cultural, life style, emotional conditions, medications, toxins, infections, hormonal imbalances and gut microbiota.
- In 2017–2018, the prevalence of obesity was estimated to be ~42% in U.S. adults (≥20 years of age) and ~18.5% of youths (2–19 years of age).
- According to a projection analysis in 2019, ~50% of U.S. adults will have obesity by 2030, with ~25% of adults having severe obesity (body mass index [BMI] ≥35 kg/m2)
- “Obesity is defined as a chronic, progressive, relapsing, and treatable multi-factorial, neurobehavioral disease, wherein an increase in body fat promotes adipose tissue dysfunction and abnormal fat mass physical forces, resulting in adverse metabolic, biomechanical, and psychosocial health consequences.”
Classification of Obesity
|Body Mass Index (BMI)|
Body mass index (BMI) in kilograms per meters squared (kg/m2)a
|Class I Obesity|
|Class II Obesity|
|Class III Obesity|
|Waist Circumference (WC)b|
|Abdominal Obesity – Men|
|Abdominal Obesity – Women|
a Different BMI cut-off points may be more appropriate based upon gender, race, ethnicity, and menopausal status. For example, among Asians, a BMI >23 kg/m2 may be a more appropriate cutoff point to define overweight and to screen for type 2 diabetes mellitus. Among postmenopausal women, BMI may underestimate percent body fat.
b Different WC abdominal obesity cut-off points are appropriate for different races (i.e., ≥ 90 centimeters for Asian men and ≥ 80 centimeters for Asian women)
Obesity As a Disease
TOP 10 TAKEAWAY MESSAGES: Obesity As a Disease
- The signs, symptoms, and pathophysiology of obesity fulfill the definition of a disease.
- Obesity can substantially be due to inheritance (genetic, epigenetic, and/or environmental inheritance).
- Obesity may result in cellular and organ anatomic abnormalities.
- Obesity may result in cellular and organ functional abnormalities.
- Obesity may result in pathogenic adipocyte and/or adipose tissue endocrine and immune dysfunctions that contribute to metabolic disease (adiposopathy or “sick fat” disease).
- Obesity may result in pathogenic physical forces from excessive body fat, promoting stress damage to other body tissues (“fat mass disease”).
- Even when exacerbated by unhealthful behavior, obesity is no less a disease than other diseases promoted by unhealthful behavior.
- Data from 2017 – 2018 estimate that approximately 42% of U.S. adults have obesity; 18.5% of youths have obesity.
- As with other diseases, obesity is best discussed using “people-first” language.
- Obesity is promoted by genetic predisposition, and shares similar pathophysiologies as aging.
Top 10 Benefits of Treating Obesity As a Disease
- Healthful nutrition (including negative caloric balance in patients with obesity) and regular physical activity often improves anatomic, physiologic, inflammatory, and metabolic body processes.
- Medically managed weight reduction in patients with obesity often improves glucose and lipid metabolism, reduces blood pressure, and reduces the risk of thrombosis.
- Medically supervised weight management programs for patients with obesity have the potential for statistically significant and clinically meaningful weight loss maintenance.
- Weight loss in patients with obesity may reduce premature all cause mortality.
- Weight loss in patients with obesity may have favorable cardiac hemodynamic effects.
- Weight loss in patients with obesity may improve obstructive sleep apnea and osteoarthritis.
- Weight loss in patients with obesity may reduce the onset of certain cancers, improve response to cancer treatments, and reduce the onset/recurrence of new cancers.
- Weight loss in women with obesity may improve metabolism (polycystic ovary syndrome), as well as improve obesity-related gynecologic and obstetric disorders. Weight loss in men may increase testosterone levels when hypogonadism is due to the adiposopathic consequence of obesity.
- Weight loss in patients with obesity may improve quality of life, improve body image, and improve symptoms of some psychiatric disorders (e.g., depression).
- Weight loss in child-bearing women (and men) with overweight or obesity may help mitigate epigenetically transmitted increased risk of obesity and metabolic disease in future generations.