The most important factor is the huge consumption of fast food and canned food compared to fresh food. It has also been observed that teenagers in the U.K. sit idle most of the times watching television or playing games which is also an important factor. This essay will discuss the significance and effects of obesity in teenagers of the United Kingdom.The World Health Organization has identified teenage obesity is one of the most serious public health challenge of the world in the 21st century. According to a number of studies and report obesity is one of the highest factors in the young population of the world. Countries like America, the United Kingdom, and Australia etc. are tremendously suffering from this problem. The term Obesity means gaining extra fat in the body by overconsumption of food. Obesity increases in the human body when the amount of calories consumed is more the number of calories required to burn by the body to produce energy (NHLBI, 2013, p.1). The extra calorie continuously deposits in the human body and forms as fat in the stomach and another part of the body. The formation of extra fat in the body slows down the flow of fluids in the body and it finally becomes the reason for severe diseases. According to the latest survey in the year 2012-13, it has been observed that there are mainly three reasons for the increase in Obesity in teenagers. Consumption of fast food at a large scale, lack of proper sleep and spending more time in front of the television by sitting idle.The most important factors for large scale Obesity is the consumption of fast food. In the modern world, it has become a trend towards fast food rather than consumption of proper fresh food. Children from a very small age prefer having fast food by skipping meals that are required for the proper function of the body. Most of the shopping malls have fast food restaurants rather than restaurants that provide a complete meal.