Obesity Disease Background

Introduction

Obesity is a chronic, progressive, and relapsing medical condition characterized by the accumulation of abnormal and/or excessive body fat that impairs health.

Epidemiology

Obesity is a common chronic condition that affects over 650 million adults worldwide with childhood obesity sharply increasing as well. The prevalence in the United States is high, as 1 in 3 adults have obesity. According to the Central Disease Control and Prevention, more than 35% are obese in at least nineteen states in the US. In Canada, 1 in 4 are obese, and prevalence continues to increase according to a recent survey in 2004 The Global Nutrition Report (GNR) and World Obesity Federation (WOF) tallied the prevalence of obesity among several countries utilizing the World Health Organization (WHO) cut-off of ≥30 kg/m² to classify obesity.  

Obesity is likewise rapidly rising in Asia. Using the WHO cut-offs, the prevalence of obesity in East Asia was only 2-4%. In China, the prevalence of obesity was 7.7% among adult men and 8.0% among adult women in 2019, according to GNR. A study that employed the China PEACE Million Persons Project which utilized an obesity cutoff of ≥28 kg/m², from 2014 to 2018 reported that the age-standardized rate of obesity was approximately 14%.  The prevalence of obesity in Hong Kong was reported to be 32.6%, using the Asia-specific cut-offs, according to the Population Health Survey conducted from 2020 to 2022. In Korea, the prevalence of obesity was 5.2% among adult men and 5.4% among adult women in 2019, according to GNR. It was reported by the Korean Society for the Study of Obesity that the prevalence of obesity was 29.7% in 2010 to 35.7% in 2018 using the Asia-specific cut-offs.

Pathophysiology

The intake of food (energy intake), physical activity (energy expenditure), environment or lifestyle, and genetic susceptibility of an individual may all play a role in the development of obesity. It was thought that excess food intake along with low physical activity creates a positive energy balance, the majority of which are then stored as fat and may cause damage in certain organs. 

Etiology

Causes of obesity are multifactorial with complex interactions. The primary cause is a chronic energy imbalance between calories consumed and expended. The assessment and management should address the root causes of obesity beyond “eat less, move more”.

Risk Factors

For the risk factor assessment, identify the absolute risk status based on the presence of the following:

• Disease conditions: Coronary heart disease, atherosclerosis, hypertension, type 2 diabetes mellitus (T2DM), obstructive sleep apnea (OSA), and dyslipidemia
• Other obesity-associated diseases: Polycystic ovary syndrome (PCOS), infertility, male hypogonadism, osteoarthritis (OA), asthma, heart failure, gallstones, urinary stress incontinence, metabolic-associated fatty liver disease (MAFLD), gastroesophageal reflux disease (GERD), proteinuria, and severe coronavirus disease 2019 (COVID-19) infection
• Cardiovascular disease (CVD) risk factors: Cigarette smoking, hypertension, hyperlipidemia, impaired fasting glucose and impaired glucose tolerance, family history of premature coronary heart disease (eg myocardial infarction [MI] or sudden death in father or male first-degree relative at ≤55 years or mother or female first-degree relative at ≤65 years), and age ≥45 years for men or age ≥55 years or postmenopausal for women
• Others: Physical inactivity, elevated serum triglyceride (TG) (>2.3 mmol/L), and decreased high-density lipoprotein cholesterol (HDL-C)