Fat Distribution
Accumulating data suggest that regional fat distribution substantially affects the incidence of comorbidities associated with obesity. Android obesity, in which adiposity is predominantly abdominal (including visceral and, to a lesser extent, subcutaneous), is strongly correlated with worsened metabolic and clinical consequences of obesity.
Waist Circumference
The thresholds used in the National Cholesterol Education Program Adult Treatment Panel III definition of metabolic syndrome state that significantly increased cardiovascular risk (metabolic central obesity) exists in men with waist circumferences of greater than 94 cm (37 in) and in women with waist circumferences of greater than 80 cm (31.5 in), as well as waist-to-hip ratios of greater than 0.95 (in men) or of more than 0.8 (in women). Circumferences of 102 cm (40 in) in men and 88 cm (35 in) in women indicate a markedly increased risk requiring urgent therapeutic intervention.
These thresholds are much lower in Asian populations. After analyzing survey results of Chinese, Malay, and Asian-Indian cohorts, a waist circumference of greater than 90 cm in men and of more than 80 cm in women were more appropriate criteria for metabolic central obesity in these ethnic groups.
Age of Obesity Onset
An elevated BMI during adolescence (starting within the range currently considered normal) is strongly associated with the risk of developing obesity-related disorders later in life, independent of adult BMI. Increases in BMI during early adulthood (age 25-40 y) are associated with a worse profile of biomarkers related to obesity than are BMI increases during later adulthood.
Intra-Abdominal Pressure
This pressure effect is most apparent in the setting of marked obesity (BMI ≥ 50 kg/m²). Pressure elevation may play a role in the following:
- Pseudotumor cerebri
- Lower-limb circulatory stasis
- Ulcers
- Dermatitis
- Thrombophlebitis
- Reflux esophagitis
- Abdominal hernias
Osteoarthritis
A study found that obesity with knee osteoarthritis resulted in the loss of a substantial number of quality-adjusted life years. The association was most notable among Black and Hispanic women.
Focal Glomerulosclerosis
Some reports suggest an association between severe obesity and focal glomerulosclerosis. This complication, in particular, improves substantially or resolves soon after bariatric surgery, well before clinically significant weight loss is achieved.
Pickwickian Syndrome
The so-called Pickwickian syndrome is a combined syndrome of obesity-related hypoventilation and sleep apnea. The hypoventilation in Pickwickian syndrome results from severe mechanical respiratory limitations to chest excursion, caused by severe obesity. The sleep apnea may be from obstructive and/or central mechanisms. Obstructive sleep apnea is common among men with collar size greater than 17 in (43 cm) and women with collar size greater than 16 in (41 cm).
Increased and Decreased Sleep Duration
- Sleep duration of less than 5 hours or more than 8 hours was associated with increased visceral and subcutaneous body fat, in a study of young African Americans and Hispanic Americans.
COVID-19
- A report released in March 2021 by the World Obesity Federation stated that the mortality risk from coronavirus disease 2019 (COVID-19) is about 10 times higher in countries where more than 50% of the adult population is classified as overweight.
Work Up
- Fasting lipid panel
- Liver function studies
- Thyroid function tests
- Fasting glucose and hemoglobin A1c (HbA1c)
Evaluation of Degree of Fat
- Caliper-derived measurements of skin-fold thickness
- Dual-energy radiographic absorptiometry (DXA)
- Bioelectrical impedance analysis
- Ultrasonography to determine fat thickness
Complications
- Metabolic syndrome
- Type 2 diabetes
- Hypertension
- Dyslipidemia
- Coronary heart disease
- Stroke
- Depression
- Non-alcoholic fatty liver disease (NAFLD)
- Infertility (women) and erectile dysfunction (men)
- Risk of stillbirth
- Gallbladder disease
- Obstructive sleep apnea
- Gastroesophageal reflux disease (GERD)
- Some cancers (e.g., endometrial, breast, and colon)
- Asthma