Food to Fuel Your Workout

Exercising? Here's what -- and when ­ to eat

By Kathleen Zelman, MPH, RD, LD
WebMD Weight Loss Clinic - Expert Column

You want your workout to burn the most calories possible. So to really get your metabolism running, it makes sense to work out on an empty stomach, right?

Wrong! It may seem counterintuitive, but you're much better off eating a snack or small meal before you exercise.

Of course, what you choose to eat and when you eat it are important to the success of your workout -- and have a profound effect on how your body uses the calories.

Timing Is Everything

Let's look at the early-morning exerciser, who hits the gym soon after jumping out of bed. It has been hours since his last meal, and his blood glucose is at the fasting level. This person is running on empty.

When your "gas tank" is on empty, your body starts to break down amino acids from your muscle mass and converts them to glucose for energy. Instead of burning fat, you're in danger of breaking down valuable muscle tissue.

To tap into those dreaded fat stores instead, eat something nutritious before you exercise. It's also a good idea to refuel after exercising with a nutritious and hydrating beverage.

There is a wealth of evidence on the role that nutrients play on blood sugar and insulin, and their effect on your energy level.

For instance, if you get up in the morning after an eight-hour sleep and down a glass of orange juice, the simple carbohydrate in the juice rapidly sends your blood sugar to elevated heights. This rise in blood glucose is followed by a rebound fall -- leaving you feeling weak and without the necessary fuel to work out. That glass of orange juice will do little to appease your appetite, so chances are you will also feel hungry.

Now, if you add a bowl of high-fiber cereal and skim milk to that glass of juice, instead of the surge in blood sugar you will have a nice, steady rise and a slow fall over the course of several hours. This meal, containing simple and complex carbohydrates, low-fat protein, and fiber, should give you enough energy to fuel your workout while helping to keep you feeling full until lunchtime.

Choosing the Right Foods

Protein and fiber slow the absorption of food in your stomach. The action of these nutrients helps maintain a normal rise and fall in blood glucose and normal insulin response.

Insulin is produced in response to the amount of glucose in the blood; its role is to help get glucose into the cells. So when your blood-glucose level surges, insulin production increases, to help shuttle that extra glucose into the cells. And what goes up must come down. When your blood sugar falls, you feel hungry -- even if you just ate two hours earlier.

People who eat meals of refined carbohydrates (orange juice, plain bagel with jelly) without protein and/or fiber fall into a vicious cycle of eating more calories throughout the day. This roller-coaster ride of high and low blood sugar leaves them hungry -- and eating every few hours.

Some scientists believe that these rapid shifts in blood sugar and insulin cause your body to deposit more fat. Others say that it's not so much the blood sugar and insulin as the excess calories you consume. Whichever theory is correct, it's clear that simple carbs without fiber or protein are the wrong choice if you are trying to lose weight.

Let Your Stomach Be Your Guide

Sometimes we use the clock to dictate when we'll eat our next meal. A better system is to use your stomach to cue you when you're hungry. Getting in touch with hunger is one of the most effective weight-management tools. But this only works if we eat complex meals containing some protein and/or fiber.

Start by making sure that most meals and snacks contain lean protein, complex carbohydrates, fiber, and/or small amounts of fat. This type of meal or snack will help slow down food absorption, help you feel satisfied, and provide fuel to energize your physical activities.

Consider dividing your eating plan into 5-6 small meals per day. More frequent, smaller meals and snacks will keep your energy level high and your hunger at bay. This approach will prevent ravenous hunger pangs and reduce the risk of overeating -- another weapon to add to your arsenal of weight-loss tricks.

Energizing Snacks and Meals

To put zip in your step, choose from a variety of complex carbohydrates, lean protein, low-fat dairy products, and healthy fats. Try to include a form of lean protein (soy, nuts, dairy, meat, fish, beans, eggs) at each meal.

Here are my Top 10 picks for healthy snacks and meals to fuel physical activity:

  • Whole-grain cereal, berries, and skim or low-fat milk
  • Oatmeal made with skim milk, sprinkled with crushed flaxseed
  • 1/2 whole-grain bagel with peanut butter and banana slices
  • Smoothie made with low-fat yogurt, fresh fruit, and orange juice
  • Poached egg on whole-wheat toast with 1/2 grapefruit
  • Salad with mandarin orange slices, slivered almonds, and veggies, drizzled with olive oil
  • Yogurt parfait with low-fat granola
  • Apple or celery slices with peanut butter and raisins
  • Meal replacement bar (Check the label to make sure it's approximately 220 calories or less.)
  • Brown rice and steamed veggies sprinkled with a little cheese

Successful weight loss is all about figuring out the tricks of the trade. Find foods you enjoy, that are satisfying, and that will keep you away from the temptations of the kitchen, break room, vending machines, and drive-throughs. Simply eating the right kinds of foods in the right amounts will give you the kind of control that leads to permanent weight loss.

Published April 8, 2004.


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