A good rule of thumb, eating 0.5 grams of carbs (approximately two calories) per pound of body weight, one hour before exercise will give you the right amount to fuel your muscles. In other words, shoot for about 300 calories (for a 150 pound person).
If the start of your workout is less than one hour, you may want to taper the amount of food to your tolerance levels. A little is better than no fuel at all.
Note: Stay away from high fiber meals prior to your workout. Foods like, bran muffins or high fiber cereals, are known to increase motility of the GI tract and can lead to cramping during exercise.
Recovery Meals
When we discuss pre-exercise meals, it's hard not to mention the importance of recovery meals. In a nutshell, for best training and muscle growth, refuel with carbohydrates and a little protein within 30 to 45 minutes of your workout. The exact proportion of carbohydrates to protein isn't as important as just getting them into your post-workout meal.
Ideal food choices would have a higher proportion of carbohydrate to protein that includes: chocolate milk, bagels, sandwiches, trail mix, or yogurt.
Remember that recovery meals don't necessarily have to be large. They can simply be used as a tool to hold you over until you are able to eat your next full meal. This provides an optimal recovery for muscles to refuel and rebuild.
Find a way to Sneak in Breakfast
From early work commutes to pre-dawn workouts, breakfast is the most common meal that is the victim of being skipped over. Instead of giving reasons why you don't have time, or it is discomforting, think about ways that you could fit it in—even if it's something really small and simple.
Keep your eating on track with a nutrition plan.