What is Obesity and Why is it Important?

Obesity is a chronic disease defined as an abnormal or excessive accumulation of fat in the body to an extent that impairs health, and it is the most important global public health problem of the 21st century. Optimed Çerkezköy Hospital Dietitian Dyt. İrem Araç shared information about obesity on World Obesity Day.

One of the most frequently used indicators in the definition of obesity is the Body Mass Index (BMI): A BMI between 25 and 29.9 is classified as "overweight," and 30 and above is classified as "obese." In addition to BMI, waist circumference measurement also plays an important role in risk assessment; a waist circumference above 88 cm in women and 102 cm in men indicates an increased health risk.

According to the World Health Organization (WHO), obesity is not merely a state of being overweight, but a disease that carries serious health risks along with metabolic and hormonal imbalances.

Obesity is not just a matter of body weight; Obesity is a major risk factor for chronic diseases such as type 2 diabetes (80% of which is associated with obesity), cardiovascular diseases (heart attack, stroke), hypertension, sleep apnea, osteoarthritis, some cancers (breast, colon, kidney, liver), fatty liver disease, GERD, gallbladder diseases, infertility, depression, and metabolic syndrome. Therefore, obesity negatively impacts not only the quality of life but also the lifespan of individuals.

Increased body fat mass is associated with an increased risk of death. Overweight and obese individuals have a life expectancy that is 5 years shorter than those who are not overweight (BMI 18.5–24.9 kg/m²).

What is the Global Scale of Obesity?

The prevalence of obesity is rapidly increasing globally. By 2025, approximately 16% of the global adult population will be classified as obese (BMI ≥30), representing more than 1 billion people worldwide. Since 1990, obesity rates have doubled in adults and quadrupled in children and adolescents.

WHO Director-General Tedros Adhanom Ghebreyesus describes obesity as "one of the most serious public health problems of our time" and states that obesity rates are expected to double globally by 2030.

The increase in overweight and obesity, particularly in childhood, has become a serious trend. Over 390 million children aged 5–19 are overweight or obese. Some projections indicate that, if strong policies and practices are not implemented, by 2050, 60% of the adult population and a significant portion of children could be overweight or obese.

Obesity Prevalence in Turkey and its Position in Europe

Turkey presents a serious picture regarding obesity in many regional and international reports. According to the World Health Organization (WHO) European Regional Report, approximately 66.8% of adults in Turkey are overweight or obese.

In Turkey, the obesity rate, which was 26.22% in 2024, increased to 32.1% in 2025. This change has been evaluated as a "rapid increase due to Westernized dietary habits."

This situation is significantly higher than the European average obesity rate of approximately 23.3%.

Causes of Obesity

Obesity is not a condition that develops due to a single factor. It is a complex process in which a number of genetic, behavioral and environmental factors play a role together:

Energy imbalance: Energy intake exceeding expenditure,
Dietary habits:
Moving away from a traditional, unprocessed food diet
Higher sugar and saturated fat intake
Increased consumption of ultra-processed foods
Larger portion sizes
Physical inactivity:
Lack of daily movement,
Sedentary jobs and screen time (60% of adults are not active enough)
Prioritizing cars over walking/cycling
Environmental factors: Settlement structure, transportation and social environment,
Socioeconomic status:
Inequalities in access to healthy nutrition and lifestyle. Stress and limited time for meal preparation
Biological and Genetic Factors
Genetic predisposition (explains 40-70% of variance)
Epigenetic changes resulting from maternal obesity
Changes in the gut microbiome
Endocrine disrupting chemicals in the environment
Psychological Factors
Emotional eating and stress
Sleep deprivation affecting metabolism
Depression and anxiety are linked to weight gain.
Mechanisms of food addiction
“8 Billion Reasons to Act Against Obesity”

World Obesity Day, celebrated annually on March 4th, aims to raise global awareness and call for action. The World Obesity Federation has chosen “8 Billion Reasons to Act Against Obesity” as its 2026 campaign theme. This theme highlights that obesity is not solely dependent on individual decisions but is directly related to environmental, economic, and social systems affecting the entire society. It emphasizes the need for all individuals, institutions, and policymakers to work together to combat obesity.

This approach is not limited to individual lifestyle changes.