What Is Obesity, And How Is It Defined?

Are you curious about what obesity truly entails and how it is exactly defined? In this article, we will explore the concept of obesity and provide you with a clear understanding of its definition. Understanding obesity is essential as it affects millions of individuals worldwide and has significant implications for health and well-being. So, let’s embark on this journey together and unravel the facts behind obesity.

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What is obesity?

Obesity is a medical condition characterized by excessive or abnormal accumulation of body fat to the extent that it may have a negative impact on overall health. It is often determined by a person’s body mass index (BMI), which is a measure of body fat based on height and weight.

Definition and Explanation

Obesity is defined as having a BMI equal to or higher than 30. BMI is calculated by dividing an individual’s weight in kilograms by the square of their height in meters. For example, if a person weighs 80 kilograms and their height is 1.65 meters, their BMI would be calculated as 80 / (1.65 * 1.65) = 29.38, indicating that they are overweight but not obese.

Prevalence and Statistics

Obesity has become a global health issue, with its prevalence increasing dramatically over the past few decades. According to the World Health Organization (WHO), in 2016, more than 1.9 billion adults were overweight, and of these, over 650 million were classified as obese. In addition, around 41 million children under the age of five were overweight or obese in 2016.

Factors contributing to obesity

Various factors contribute to the development of obesity, including genetic, environmental, and socioeconomic factors.

Genetic factors

Research suggests that genetics may play a role in determining an individual’s susceptibility to obesity. Certain gene variations can affect metabolism, the regulation of fat storage, and appetite control, making some people more prone to gaining weight.

Environmental factors

The modern environment is packed with factors that promote unhealthy eating habits, sedentary lifestyles, and weight gain. Easy access to high-calorie processed foods, the prevalence of fast-food chains, and the promotion of unhealthy foods through advertising all contribute to the obesity epidemic.

Socioeconomic factors

Socioeconomic factors, such as income and education level, can also impact the likelihood of developing obesity. Individuals with lower incomes may have limited access to affordable, nutritious food, and safe places to exercise. Additionally, stressors associated with low socioeconomic status can contribute to emotional eating and an increased risk of obesity.


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Health consequences of obesity

Obesity is not just a cosmetic concern; it is associated with a wide range of health consequences, both physical and mental.

Cardiovascular diseases

Obesity significantly increases the risk of developing cardiovascular diseases, including coronary artery disease, heart attacks, and stroke. Excess weight puts strain on the heart, leading to high blood pressure, high cholesterol levels, and the accumulation of plaque in the arteries.

Type 2 diabetes

Obesity is closely linked to the development of type 2 diabetes. Excess body fat can impair the body’s ability to use insulin properly, leading to high blood sugar levels and an increased risk of developing diabetes.


Obesity has been identified as a major risk factor for various types of cancer, including breast, colon, kidney, and pancreatic cancer. The underlying mechanisms linking obesity to cancer are complex, but hormonal imbalances, chronic inflammation, and alterations in insulin signaling are believed to play a role.

Joint problems

Excess weight puts a significant strain on the joints, particularly in the knees and hips. This can lead to the development of joint problems such as osteoarthritis, where the protective cartilage wears away, causing pain, stiffness, and reduced range of motion.

Sleep apnea

Obesity is a leading cause of sleep apnea, a sleep disorder characterized by pauses in breathing during sleep. Excess fat in the neck and throat can obstruct the airway, leading to loud snoring, disrupted sleep, and daytime fatigue.

BMI and obesity

BMI is a widely used tool to assess whether an individual is underweight, normal weight, overweight, or obese.

Body Mass Index (BMI)

Body Mass Index (BMI) is calculated by dividing a person’s weight in kilograms by the square of their height in meters. It provides an estimate of the amount of body fat a person has.

BMI categories

Based on BMI, individuals can be classified into different categories:

  • Underweight: BMI below 18.5
  • Normal weight: BMI between 18.5 and 24.9
  • Overweight: BMI between 25 and 29.9
  • Obese: BMI equal to or higher than 30

Limitations of BMI

While BMI is a useful screening tool, it has certain limitations. For instance, it does not differentiate between fat and muscle mass, so athletes with a higher muscle mass may have a higher BMI despite having a low body fat percentage. Additionally, it does not account for variations in body shape and fat distribution, which can impact a person’s overall health.

What Is Obesity, And How Is It Defined?

Waist circumference and obesity

In addition to BMI, measuring waist circumference is another valuable way to assess abdominal obesity.

Measurement of waist circumference

Waist circumference is measured using a tape measure, horizontally placed around the smallest part of the waist, typically just above the navel. The measurement is taken at the end of a gentle exhalation.

Importance of waist circumference

Abdominal obesity, characterized by excess fat accumulation in the abdomen and around the waist, is associated with an increased risk of developing obesity-related health conditions. Waist circumference provides a more accurate estimate of abdominal fat and can help identify individuals with a higher risk of developing these health problems.

Health risks associated with abdominal obesity

Excess abdominal fat is closely linked to an increased risk of cardiovascular diseases, type 2 diabetes, and metabolic syndrome. It is believed that fat stored in the abdomen releases more harmful substances, such as cytokines and free fatty acids, which can contribute to chronic inflammation and insulin resistance.

Types of obesity

Obesity can manifest in different ways and present varying health risks.

Visceral obesity

Visceral obesity refers to the accumulation of fat around the internal organs, particularly in the abdominal area. This type of obesity is associated with an increased risk of cardiovascular diseases, type 2 diabetes, and metabolic syndrome.

Subcutaneous obesity

Subcutaneous obesity is characterized by the accumulation of fat directly underneath the skin. While excess subcutaneous fat is a cosmetic concern, it is generally associated with lower health risks compared to visceral obesity.

Android obesity

Android obesity, often referred to as “apple-shaped” obesity, is characterized by excess fat accumulation in the upper body, particularly around the abdomen, chest, and shoulders. This type of obesity is associated with a higher risk of cardiovascular diseases and metabolic syndrome.

Gynoid obesity

Gynoid obesity, also known as “pear-shaped” obesity, involves excess fat accumulation in the hips, buttocks, and thighs. While gynoid obesity may have less detrimental health effects compared to android obesity, it can still contribute to joint problems and hinder mobility.

What Is Obesity, And How Is It Defined?

Childhood obesity

Childhood obesity has emerged as a significant public health concern, with long-term implications for physical and mental health.

Definition and prevalence

Childhood obesity is defined as having a BMI equal to or higher than the 95th percentile for children of the same age and sex. This condition affects an alarming number of children worldwide, with the WHO estimating that over 340 million children and adolescents aged 5-19 were overweight or obese in 2016.

Causes and risk factors

Various factors contribute to the development of childhood obesity, including genetic predisposition, unhealthy eating habits, lack of physical activity, sedentary behaviors, and socioeconomic factors. The availability of high-calorie processed foods, marketing strategies targeting children, and reduced opportunities for physical activity in schools and neighborhoods all play a role.

Effects on physical and mental health

Childhood obesity can lead to a range of immediate and long-term health consequences. In the short term, obese children may experience physical health issues such as high blood pressure, type 2 diabetes, and sleep apnea. Mentally, they may face social stigma, low self-esteem, and an increased risk of developing psychological disorders such as depression and anxiety. Furthermore, obese children are more likely to become obese adults, perpetuating a cycle of poor health.

Diagnostic criteria for obesity

Several organizations have established diagnostic criteria for obesity, providing guidelines for both healthcare professionals and individuals.

World Health Organization (WHO) criteria

The WHO defines obesity in adults as having a BMI equal to or higher than 30. In children, obesity is determined by comparing their BMI to age and sex-specific growth charts.

American Medical Association (AMA) criteria

The AMA classifies obesity into three categories based on BMI: Class I (BMI 30-34.9), Class II (BMI 35-39.9), and Class III (BMI equal to or higher than 40). The AMA also considers waist circumference as a complementary measurement for diagnosing obesity-related health risks.


Treatment options for obesity

Addressing obesity requires a multifaceted approach, incorporating lifestyle changes, dietary interventions, physical activity, medical interventions, and in some cases, surgical options.

Lifestyle changes

Lifestyle changes play a crucial role in managing obesity. This includes adopting a balanced and nutritious diet, engaging in regular physical activity, managing stress levels, getting adequate sleep, and creating a supportive environment that promotes healthy behaviors.

Dietary interventions

Dietary interventions focus on promoting a calorie-controlled diet that emphasizes whole, unprocessed foods rich in nutrients. This includes reducing the consumption of sugary beverages, high-fat foods, and processed snacks, while increasing the intake of fruits, vegetables, lean proteins, and whole grains.

Physical activity and exercise

Regular physical activity is essential for weight management and overall health. Incorporating a combination of aerobic exercise, strength training, and flexibility exercises can help burn calories, build lean muscle mass, and improve cardiovascular fitness.

Medical interventions

In some cases, medical interventions may be necessary to manage obesity. This can include the prescription of weight-loss medications that work by suppressing appetite, reducing the absorption of fat, or increasing metabolism. Medical professionals closely monitor individuals using these medications to ensure their safety and effectiveness.

Surgical options

For individuals with severe obesity who have not been successful with other weight-loss methods, bariatric surgery may be considered. This includes procedures such as gastric bypass, gastric sleeve, and gastric banding, which aim to reduce the size of the stomach or bypass a portion of the digestive tract, leading to weight loss.

Prevention strategies for obesity

Preventing obesity is crucial to curbing the global obesity epidemic. Implementing preventive strategies at the societal and individual levels can help promote healthy lifestyles and reduce the prevalence of obesity.

Promoting healthy eating

Efforts should be made to promote healthy eating habits by improving access to affordable, nutritious food options, implementing clear food labeling, and reducing the marketing of unhealthy foods to children. Schools, workplaces, and communities can also play a role in providing educational programs and supportive environments that encourage healthy eating.

Encouraging physical activity

Creating opportunities for regular physical activity is essential in preventing obesity. This includes promoting active transportation, providing safe and accessible recreational spaces, integrating physical activity into school curricula, and encouraging workplace wellness programs.

Education and awareness programs

Raising awareness about the consequences of obesity and providing education on healthy lifestyles is key to prevention. Public health campaigns, community outreach programs, and school-based initiatives can help individuals develop a better understanding of the impact of their choices and encourage behavior change.

Policy changes

Policy changes aimed at creating healthier environments can have a significant impact on obesity prevention. This can include implementing regulations on the marketing of unhealthy foods to children, increasing access to nutritious food in underserved communities, and incorporating physical activity guidelines into urban planning.

In conclusion, obesity is a significant public health issue with far-reaching consequences for individuals and society as a whole. Understanding the factors contributing to obesity, recognizing its health consequences, and implementing effective prevention and treatment strategies are essential in addressing this complex and multifaceted problem. By promoting healthy lifestyles, creating supportive environments, and advancing public health policies, we can work towards reducing the prevalence of obesity and improving overall well-being.

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W. Aubyn Manderson
W. Aubyn Manderson

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