Since you are growing, you may find that you are more hungry, or are hungry more often. This is perfectly normal, as long as you need the extra calories to grow.
Overeating and not exercising can lead to unhealthy weight and body conditions. Obesity is defined as having 20% more than the "ideal" body weight for someone your age and height. If you think that you may be overweight or obese, talk to your parents or doctor about ways to become healthier.
If you want to eat healthy, it is important to make healthy choices in what you eat all the time – meaning: meals and snacks.