Obesity – Causes, Types, Pathophysiology, Complications and Prevention

1. Introduction

Obesity is one of the most common lifestyle disorders in modern society. It occurs when excess body fat accumulates in the body, which can negatively affect health and increase the risk of many diseases.

The word Obesity comes from the Latin word “Obesus”, which means fat or stout.

Due to sedentary lifestyle, unhealthy diet, and reduced physical activity, the number of obese individuals is increasing rapidly worldwide.

2. Definition of Obesity

Obesity is defined as a medical condition in which excessive body fat accumulates to the extent that it impairs health and reduces life expectancy.

One of the most common methods to define obesity is Body Mass Index (BMI).

BMI Classification

Normal weight: 18.5 – 24.9

Overweight: 25 – 29.9

Obesity: BMI ≥ 30

BMI is calculated by:

BMI = Weight (kg) / Height (m²)

3. Difference Between Overweight and Obesity

Overweight

Overweight refers to increased body weight due to multiple factors, such as:

Fat

Fluid retention

Muscle mass

Bone density

Tumors

Obesity

Obesity specifically refers to excess accumulation of fat (adipose tissue) in the body.

4. Epidemiology of Obesity

Obesity has become a major global health problem.

Important statistics include:

The worldwide prevalence of obesity nearly tripled between 1975 and 2016.

In 2016, more than 1.9 billion adults were overweight.

Among them, over 650 million people were obese.

About 39% of adults were overweight, while 13% were obese.

More than 340 million children and adolescents (5–19 years) were overweight or obese.

This shows that obesity is a rapidly increasing global epidemic.

5. Measurement of Obesity

Several methods are used to assess obesity.

1. Body Mass Index (BMI)

The most commonly used method.

2. Waist-Hip Ratio

Measures fat distribution in the body.

3. Skin Fold Thickness

Measures subcutaneous fat using calipers.

4. Air Displacement Plethysmography

A modern method to measure body composition.

5. Total Body Electrical Conductivity

Used to measure body fat percentage.

Among these, BMI and Waist-Hip Ratio are most commonly used in clinical practice.

6. Pathophysiology of Obesity

The development of obesity involves several metabolic changes.

Stepwise mechanism

Excess calorie intake + Sedentary lifestyle

↓

Positive energy balance

↓

Increased triglyceride storage in adipocytes

↓

Adipocyte hypertrophy and hyperplasia

↓

Metabolic disturbances

Major metabolic changes in obesity

1. Leptin Resistance

Leptin hormone regulates appetite.

In obesity, leptin resistance occurs.

As a result, appetite is not suppressed.

2. Insulin Resistance

Leads to hyperinsulinemia

Causes increased fat storage

Major risk factor for Type 2 diabetes

3. Chronic Inflammation

Fat tissue releases inflammatory cytokines.

Causes low-grade chronic inflammation.

4. Increased Free Fatty Acids

Fat deposition occurs in liver and muscles.

This leads to metabolic complications like:

Type 2 Diabetes

Hypertension

Dyslipidemia

Cardiovascular disease

7. Types of Obesity

Obesity can occur due to different causes.

1. Inactivity Obesity

Caused by lack of physical activity.

Sedentary individuals burn fewer calories, resulting in fat accumulation in different body parts.

2. Food Obesity

Occurs due to:

Overeating

High sugar intake

Unhealthy diet

Excess fast food

Fat mainly accumulates in the abdominal region.

3. Anxiety Obesity

Caused by:

Anxiety

Stress

Depression

These conditions may cause emotional overeating.

Treatment includes:

Stress management

Reduced caffeine intake

Medical treatment if necessary.

4. Venous Obesity

This type is often genetic and related to poor venous circulation.

It is commonly seen in:

Pregnant women

Individuals with family history of obesity

Regular exercise helps improve circulation.

5. Gluten Obesity

Most common in women.

It occurs during hormonal changes such as:

Puberty

Pregnancy

Menopause

6. Atherogenic Obesity

In this type, fat accumulates mainly in the abdomen (central obesity).

This type is very dangerous because it increases the risk of:

Heart disease

Breathing problems

Metabolic syndrome

Avoiding alcohol and maintaining healthy lifestyle is important.

8. Causes of Obesity

Several factors contribute to obesity.

1. Behavioral and Lifestyle Factors

Unhealthy dietary habits

Physical inactivity

Easy availability of fast food

Lack of nutritional knowledge

Food marketing and advertising

Poor physical activity environment

Sedentary Lifestyle

People with sedentary lifestyles burn fewer calories, which leads to weight gain.

Studies show strong correlation between physical inactivity and obesity.

Medications

Certain medications can cause weight gain, such as:

Antidepressants

Anticonvulsants

Diabetes medications

Oral contraceptives

Corticosteroids

Antihistamines

2. Diseases

Some diseases can lead to obesity.

Examples include:

Cushing’s disease

Polycystic ovary syndrome (PCOS)

Thyroid disorders

Endocrine disorders

Depression

Eating disorders

3. Genetic Factors

Genetics also play an important role in obesity.

If one or both parents are obese, the risk increases.

Some genes affect hormones involved in fat regulation.

Example: Leptin deficiency.

9. Health Consequences of Obesity

Obesity affects almost every organ system.

Major complications include:

1. Hypertension

2. Dyslipidemia

3. Type 2 Diabetes

4. Coronary heart disease

5. Stroke

6. Gall bladder disease

7. Osteoarthritis

8. Sleep apnea and obesity-related asthma

9. Cancers (breast, colon, liver, endometrial)

10. Mental illness

11. Chronic pain

12. Reduced quality of life

10. Prevention of Obesity

Obesity is largely preventable with healthy lifestyle changes.

Lifestyle Assessment

Doctors should:

Check BMI regularly

Evaluate dietary habits

Assess physical activity

Identify family history

Identify medication use

Evaluate nutrition knowledge

11. Physical Activity Recommendations

For Children and Adolescents

At least 1 hour of physical activity daily

Activities should include:

Aerobic exercise

Muscle strengthening

Bone strengthening activities

For Adults

Recommended physical activity includes:

150 minutes moderate exercise per week OR

75 minutes vigorous exercise per week

Additional activities include:

Strength training (2–3 days/week)

Balance and coordination exercises

Flexibility exercises

12. Dietary Prevention (Primary Prevention)

Healthy dietary habits include:

Eating nutritious and balanced diet

Avoiding high-calorie foods

Reducing sugary drinks

Encouraging family meals

Limiting fast food consumption

Promoting breastfeeding in infancy

13. 5-2-1-0 Rule for Children

A simple guideline to prevent obesity in children:

5 servings of fruits and vegetables daily

2 hours or less screen time

1 hour of physical activity daily

0 sugary drinks (drink water instead)

Conclusion

Obesity is a major preventable lifestyle disorder affecting millions of people worldwide. It results from excess calorie intake, sedentary lifestyle, genetic factors, and certain diseases.

Since obesity increases the risk of serious conditions such as diabetes, heart disease, and cancer, prevention through healthy diet, regular exercise, and lifestyle modification is extremely important.

Early awareness and proper health education can help reduce the global burden of obesity.

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