I'm a 17 year old guy and i have trouble gaining weight. is there any way i could gain weight in less time?

Some people are: naturally thin (ectomorphs). Changing your body type takes a lot of commitment. The healthiest way to "gain weight" is to eat a diet of balanced proteins and complex carbs (not junk food), with daily aerobics and weight lifting. If your BMI is very low, you may have a nutrition issue that needs evaluation by an adolescent expert. Consider a HealthTap consultation for additional guidance.