Obesity is a common nutritional concern during adolescence. the availability of fast food is a major contributor to adolescent obesity because

Obesity is a common nutritional concern during adolescence. The availability of fast food is a major contributor to adolescent obesity because:  it delivers large portions of high-calorie and high-fat food at low prices
The type of calories that provided in the fast-food joints are mostly empty calories. Which is a form of calories that does not give us the sense of 'fullness' and it's really addictive