Why Do We Become Obese?
Obesity can be defined as excess fat storage in the body. Although this seems like a problem; this phenomenon can also be considered as an adaptation for survival. In nature, living things constantly need energy to survive. Fat is a strategy for storing energy. Fat storage acts as a reservoir to maintain vitality in situations where the flow of nutrients is interrupted. Many living things in nature convert energy into fat and store it. Fat provides more energy per unit than carbohydrates and proteins, which are our other organic food sources. Fat is a food that gives high energy by breaking down when needed. It is also used to regulate body temperature. Both are vital for the continuation of life. Apart from this, adipose tissue also has different physiological functions such as being in the structure of various organs, protecting the organs from trauma by wrapping them around, producing various hormones, contributing to the immune system, and secreting cytokines.
Historically, obesity began to emerge 12 thousand years ago when people settled down and started farming. Obesity is the result of the interaction of our genetic makeup and the environment. There are different views regarding the interaction of our genetic structure with nature and its evolutionary process (1). In developed countries, especially fast food-style nutrition and lack of physical activity and excess calories have contributed to the obesity pandemic, and it has been stated that the majority of individual susceptibility to obesity (60-70%) can be explained by genetic tendency. Hundreds of markers associated with obesity and 97 gene loci associated with body mass index have been identified in our genome (2). The fact that the tendency to obesity and the frequency of obesity are different among people of different ethnic origins can be considered as another indicator of the influence of genetic factors.
People used to live as hunter-gatherers. They had intense physical activity and a high protein/low carb menu. With settled life and agriculture, this diet has become high carb/low protein. While low insulin sensitivity suitable for a high protein/low carbohydrate diet means being able to store fat and survive; when the diet changes, this adaptation appears as obesity. The sedentary life brought with it more influence from the changing climatic conditions. With variable climatic conditions, people went through periods of famine and abundance. Those capable of storing enough fat during times of famine survived and multiplied. The ability to store fat may have provided an advantage over both changing ecological conditions and other individuals of the species. From this point of view, it can be said that obese individuals have the ability to adapt to survive. However, in modern life, this adaptive ability is paradoxically associated with poor health through excess weight gain and obesity-related diseases. Similarly, many non-human species become overweight when exposed to an industrialization-type life similar to humans. Many primate species and pets become obese in captivity.
For centuries, obesity has been associated with well-being, strength, fertility and health. For example, Cybele, one of the Anatolian mother goddesses, is depicted as obese. Technological advances that began in the 18th century have improved public health and life expectancy. Obesity was accepted as an aesthetic problem in the late 19th century and as a health problem in the 20th century. Awareness that obesity is a serious health problem is only a few decades (50-75) years old. Obesity has become a global threat today and it seems that the measures taken are not successful. Therefore, it is important to raise awareness about obesity. If the current trend continues, it is predicted that overweight and obese individuals will constitute 60% of the world population in 2030 (3).