In addition, exercise often creates more hunger – because you are using more calories you need more fuel. If you are eating your fuel via junk food you are only filling your tank with junk. The body then struggles to help you rebuild tissue and have what it needs to make sure you are strong and ready for your next workout.
Planning your meals and making sure to follow the 80/20 rule when choosing foods is important. Here 80% of the time you are on track for your goals (weight loss, maintenance, or gain) and 20% of the time you eat what you want. This can be looked at according to the hour, day, week, etc.
Check out E-Meals for help making healthy meal planning easy!