Scheduling proper eating time into a busy lifestyle is not always easy. Fitting exercise into the mix requires even more planning.

One of the trickiest parts is making sure you have enough fuel to run on without getting nailed by stomach cramps, nausea, or sluggishness.

But if you try "running on empty," you may feel weak and lose steam even faster.

So, what should we do? Here are some eating guidelines to keep you going strong:

Eat a full breakfast
Wake up early enough to eat a full breakfast. "Most of the energy you got from dinner last night is used up by the morning," says Stephen DeBoer, a registered dietitian at Mayo Clinic, Rochester. "Your blood sugar is low. If you don't eat, you may feel sluggish or lightheaded while exercising." If you plan to exercise within an hour after breakfast, eat a smaller breakfast or drink a smoothie to raise your blood sugar. A large breakfast may be troublesome if you are going for a morning run, but is fine for a jog before lunch.

Time your meals
When you eat a large meal, extra blood is sent to your intestines to pick up the newly digested nutrients. But if you start vigorous exercise, the body diverts the blood away from the digestive system to help your muscles work.

This is a great survival strategy when you are escaping from a saber tooth tiger, but it doesn't work so well for your "eat and run" lifestyle. The body literally begins to shut down the digestion process, which can cause everything from nausea, to cramps, or even diarrhea.

Your goal at the time of your workout should be to have nutritious fuel in your body, but not in your stomach. The ideal timing for exercise is:

• 1/2 hour after a light snack.
• 1 hour after a light meal, heavy snack, or smoothie.
• 2 hours after a regular meal.
• 3 hours after a Thanksgiving-type feast (large meals can take up to six hours to empty from the stomach).

Also be sure to eat carbohydrate foods, such as fruits, vegetables, and grains. Carbohydrates are digested faster and more easily than proteins and fats, and the faster foods are removed from the intestinal system, the sooner you can exercise. You might want to consider how you combine your foods, too.

Don't Skip Meals
Not eating before you exercise can be just as bad as eating too much. Skipping meals may cause low blood sugar which can make you feel weak, faint, tired or lightheaded and your mental abilities may be affected, making you slower to react. If you exercise when the body is depleted or feeling hungry, like before breakfast, you may not be increasing the amount of fat you burn but instead causing protein to be sacrificed as fuel.

Snacking
If you're short on time before your workout, and your choice is a quick snack or nothing, go ahead with the snack because it can improve your performance compared with eating nothing.

But be wary of what you eat: if your snack is high in sugar and low on nutrients it could be worse than eating nothing at all.

A snack of fresh fruit, dried mango, goji berries, or golden berries is a good choice.

You can also make a light smoothie, mostly with water or coconut water and a blend of superfood extracts (like camu camu, mangosteen, or purple corn), or a blend of berries, like goji or goldenberry, or even a fructose-based sweetener like yacon or agave. Not only are these good fuels for pre-exercise, they can serve as an all-natural sports drink to sip on during your run.

Since new studies are indicating that eating chocolate before exercise may permanently improve brain function, you may want to try a low-fat (and more-easily digested) variety of chocolate, such as cacao powder, blended with some water and a low-glycemic sweetener like yacon or agave. To enhance the cacao's energy boost, try adding a small spoonful of Maca.

Snacks, depending on their content, take about an hour to leave your stomach. Eating a high-carbohydrate snack two hours before exercising can leave you ample energy and a calm stomach for a great workout.

*Remember that consuming sweets (such as honey, candy, or soda) immediately before exercise does not provide a quick burst of energy, but may cause a rise in insulin followed by a drop in blood sugar resulting in fatigue.

Hydrate Well
Be sure you’re well hydrated before exercise. If you don’t believe you lose much water during exercise, weigh yourself immediately before and after your workout. The difference is water loss. Ideally, you should consume adequate fluids during the workout so that your weight remains about the same.

Drinking water during exercise does not cause upset stomach or cramps; whereas restricting water during exercise may cause severe dehydration and limit performance. Be aware that exercise blunts the sense of thirst: if you wait until you notice your thirst, you’re already becoming dehydrated. So whether you feel thirsty or not, drink 1/2 cup of water every 10-15 minutes while you work out.

And beware drinking sugary, sodium-filled exercise drinks. These "lab-formulated" drinks are little more than diluted soda.

You can make your own, all-natural exercise drink at home. If you want to replace sodium lost from sweating, try juicing about four ribs of celery, then add some coconut water for electrolytes, potassium, and sweetness. For a little more flavor (as well as vitamins, minerals, and phytonutrients) try adding a blend of superfood extracts (like camu camu, mangosteen, or purple corn), or a blend of berries, like goji or goldenberry. A spoonfull of cacao powder will give you an energy lift (along with antioxidants and brain-boosting nutrients).

Eat After Your Workout
To help your muscles recover and to replace their glycogen stores, within two hours of your exercise session you should eat a meal that contains both protein and carbohydrates. The ideal post-exercise snack is light and nutritious, containing mainly carbohydrates and protein in a ratio of about 2:1.

Maca perfectly meets this ratio, plus, it's full of potent nutrients and functional phytochemicals that re-balance hormone levels and replenish energy stores. Maca doesn't taste great by itself, but blends nicely with water, coconut water, and berries (like goji or golden berries). Try anywhere from a teaspoon up to two or three tablespoons in a smoothie, or else sprinkle a bit into rice or oatmeal.

If you're looking to fill out a post-workout smoothie with some extra protein (especially if you've been doing more weight-lifting than aerobic exercise), then try adding some brazil nut powder or mesquite powder to your smoothies, soups and sauces.

At the end of the day, your body is the boss. Listen to how it reacts to what you put in it and do what works best for you. For optimum exercise performance and to achieve the best results, be sure to consume a healthy, well-balanced diet all through the day!