Nutrition Articles

High Performance Nutrition - Part 1

The Big Picture: Food as Fuel

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Fact #2: The fuel you use during exercise doesn't come from your most recent meal.

It takes time to digest your food and turn it into glycogen, which is the primary fuel your muscle cells actually use during exercise. Glycogen is made out of glucose (which comes from carbohydrates) and is stored in both your muscle cells and liver. As long as you're eating enough nutrients to meet your activity needs, your body can store enough glycogen to handle about 2000 calories worth of high-intensity activity or 4000 calories worth of lower-intensity activity—even if you haven’t eaten in a while.

If you’re highly active, you should plan your meals and snacks so that you don’t run out of muscle glycogen at the wrong time (like in the middle of an exercise session). A marathon runner can deplete her glycogen stores before the end of a single race (called “bonking” or “hitting the wall”). A more casual exerciser can run out of glycogen after a few days of not eating enough carbohydrates and total calories to replace it.

Action Step: Eat enough total calories to support your activity level. The combination of a low-calorie diet and a high level of exercise will force your body to breakdown muscle tissue to meet your immediate energy needs. Total calorie deficits of more than 500-1000 calories per day will actually inhibit exercise performance—even for moderate exercisers.

Fact #3: Planning nutritious meals will help you recover from exercise.

The most important window for replenishing glycogen is the four to five hours immediately after a vigorous exercise session. During this time, the enzymes responsible for this process are more active and effective.

Most healthy people don’t really need to eat immediately before exercise. But eating a small snack or meal 20-60 minutes before an exercise session will trigger an insulin response that helps glucose enter your muscle cells, making it easier to exercise without discomforts like dizziness, faintness, or a general lack of energy. But if you or your stomach prefers not to eat before a workout, you should have plenty of muscle glycogen to fuel one to two hours of moderate to vigorous exercise before eating. To learn more about exercising in the morning or on an empty stomach, read this Ask the Expert Q & A.

Action Step: Eat a good post-exercise meal. Sports nutritionists recommend that active people eat about 250-300 calories (with a 4:1 ratio of carbs to protein) within 90 minutes after exercising. This breaks down to about 50-60 grams of carbs and 12-15 grams of protein.

Putting It All Together

When you put these facts together into one big picture, you can see that keeping your glycogen tanks topped off is the key factor to maintaining your ability to perform at a high level while losing weight; the Action Steps outlined above will help you do just that.
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About The Author

Dean Anderson Dean Anderson
Dean Anderson has master's degrees in human services (behavioral psychology/stress management) and liberal studies. His interest in healthy living began at the age of 50 when he confronted his own morbid obesity and health issues. He joined SparkPeople and lost 150 pounds and regained his health. Dean has earned a personal training certification from ACE and received training as a lifestyle and weight management consultant. See all of Dean's articles.

Member Comments

  • AKHAN26
    this article help me a lot and thanks for sharing this article
    toshippuden-e - 7/15/2015 4:52:57 PM
  • I do not find this article credible. - 11/21/2014 10:21:19 AM
    I have tried following the Spark People guidelines for carbs (whole meal, pulses) for WEEKS and lost NOTHING, NADA, ZIP eating below my base calorie needs of 1500 and meeting exercise guidelines. Rather than go to 1200 calories a day - unsustainable in long run - I decided to go low carb, tapering down to 70 then 50 carb grams a day, higher fat, limited protein (around 100g day). Finally the weight started to come off without my having to feel like I'm starving. I'm not an expert but the 150g/day carb does not seem to work for me. Neither does having high protein at over 150g a day, which my trainer recommended. I did talk to a Dr - endocrinologist - who said that the body converts protein to glycogen as needed, so that's not a reason to avoid low carb. BTW, I did get very tired when I tried low carb dieting in the past - apparently due to mineral loss with water loss - but have found this time around that taking vitamins and minerals helps a lot. Am going to try bumping up my carbs from time to time to keep the metabolism going and stave off the boredom. - 8/12/2014 1:45:13 PM
  • The government are insane for leaving this sort of basic yet vital information out of our education systems! invaluable article. Thank you! - 8/5/2014 7:33:23 AM
  • This is exactly the information I have been looking for, and could not find anyone that would tell me. Not even a doctor. Thank you Spark. - 10/4/2013 11:16:01 PM
    I try and do carb balancing. I subtract the grams of fiber from my carbs and try and have that match (or be under) my protein. I ALWAYS make sure I have at least 100 grams of carbs but I have PCOS and other health issues and have been told that carb balancing is the healthiest for me since it keeps my blood sugar level. I am finding it REALLY hard to lose some weeks. I've been eating between 1200 and 1400 and get anywhere between 120-30 mins of exercise a day. - 8/22/2013 6:48:04 PM
  • Great article - 6/26/2013 12:35:28 PM
  • Great information. - 6/18/2013 7:48:25 PM
  • RON562
    Very good article. My problem is I'm starving hungrey after I workout and that's where I fail. - 5/22/2013 11:15:04 PM
    good article except for the bit about needing carbs - carbs are NOT a necessary macronutrient. Take for example the Inuits, Eskioms. They function perfectly well on a ketogenic diet - better heart health and overall health. Recent advances in science, exercise physiology and science and sport psychology has shown that most people and almost all athletes can function at high intensity perfectly, even better in most cases after the initial down time adaptation phase. People are omnivorous and carbohydrates that come from anything other than vege, esp dark green vege are unnecessary for survival and/or high intensity exercise. Good article otherwise. Eat your fats, lots of them! :-) - 6/20/2011 8:01:35 PM
    I love reading Dean"s article. Please Dean write more it"s great. - 12/27/2010 9:57:22 AM
  • Love those Dean Anderson articles! They are so well written and informative. Keep them comin'! - 6/10/2010 11:19:07 AM
    One comment I'd add is that certain long endurance activities do require nourishment during the event. I've competed in 5+ hour cycling events. Ultra-endurance events can last over 24 hours.

    When I ran high school track our coach told us not to eat anything 3 hours before our training or event. When I started to cycle long enough to require food I couldn't handle it; it seems you have to train your body to send a little blood to your stomach even when your legs want it all. For a while I felt ill no mater what I ate while cycling hard. After I got used to it I found myself looking forward to a snack; in fact now I start to feel a little peckish 20 miles into most rides. - 2/8/2010 5:08:17 PM

    from an avid runner struggling with weight loss and how the body actually works....THANK YOU! - 11/16/2008 1:37:24 PM
  • This is a well written article. I heart Coach Dean (and carbs) ! - 10/22/2008 2:39:17 PM

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