Fast food has become a widespread dietary phenomenon in modern societies, closely linked to changes in lifestyle, the rapid pace of daily life, and the growing reliance on ready-made meals due to time constraints and easy accessibility. Despite the convenience and speed these meals offer, excessive consumption has led to a range of serious health challenges that now pose a real threat to public health across different age groups. Fast foods are typically high in saturated fats, sugars, and salt, while being poor in essential nutrients such as vitamins, fiber, and minerals. This nutritional imbalance contributes over time to weight gain and obesity, which are among the most serious health problems of the contemporary era. Obesity significantly increases the risk of chronic diseases, including cardiovascular diseases, high blood pressure, and type 2 diabetes. Alarmingly, these conditions are now appearing at younger ages as a direct result of frequent fast-food consumption. Moreover, excessive intake of fast food negatively affects digestive health. The lack of dietary fiber often leads to digestive disorders such as constipation, indigestion, and irregular bowel movements, and may increase the long-term risk of certain colon diseases. In addition, the heavy use of preservatives and artificial flavorings can irritate the stomach lining and disrupt the balance of beneficial gut bacteria, further compromising digestive function. The consequences of fast-food consumption are not limited to physical health; they also extend to mental and psychological well-being. Numerous studies indicate a clear relationship between unhealthy eating patterns and higher rates of anxiety, depression, and mood instability, particularly among children and adolescents. This is largely attributed to deficiencies in nutrients essential for proper brain function, including vitamins, minerals, and beneficial fatty acids. Another major health challenge associated with fast food is elevated levels of harmful cholesterol in the blood due to the presence of trans fats. This increases the risk of atherosclerosis, heart attacks, and strokes. Furthermore, the high sodium content of fast foods contributes to fluid retention and high blood pressure, placing additional strain on healthcare systems and increasing the cost of medical treatment and long-term care. The risks become even more severe when fast food forms a core part of children’s diets. Such eating habits can hinder physical and cognitive development, weaken the immune system, and establish unhealthy dietary patterns that persist into adulthood. This trend threatens the health of future generations and makes societies more vulnerable to chronic diseases. In conclusion, fast food represents a major public health challenge that requires coordinated efforts from individuals, healthcare institutions, educational systems, and the media. Raising nutritional awareness, promoting healthy and balanced diets, and reducing dependence on fast food are essential steps toward protecting public health. Ultimately, a healthy society begins with proper nutrition, which forms the foundation for building a physically and mentally sound population capable of contributing effectively to sustainable development and social stability.