By Matt Fitzgerald
Sept. 12, 2007 — Most Americans have one major nutritional concern: trying not to eat too much. However, there are at least three classes of Americans who sometimes struggle to get enough daily calories to meet their needs: the very poor, persons with eating disorders, and endurance athletes—especially female endurance athletes.
There are, of course, endurance athletes with eating disorders, but much more common are runners, cyclists, and triathletes who burn a lot of calories in training, are careful but not pathological in their eating habits, and live in a chronic state of mild undernourishment.
I am not a practicing clinical sports nutritionist, but I have been assured by practicing clinical sports nutritionists that they more often have to increase the food intake of their female competitive endurance athletes than help them eat less. Recently, Paul Goldberg, M.S., R.D., C.S.C.S., who is the strength and conditioning coach for the Colorado Avalanche and who also works with individual clients at a facility in Evergreen, Colo., described one such case to me. Here’s what he said:
Stephanie was a 24-year-old recreational triathlete when I started working with her. She was already fit and healthy, with solid dietary habits and a low, 16-percent body fat measurement. Her one complaint was that she was experiencing a lack of energy that was affecting her training. I looked into the timing of her meals and quickly saw that she was not getting enough calories before and during her workouts, to fuel performance, nor after workouts, to speed her body’s recovery from training. So we moved roughly 300 total calories from her lunch and dinner and added them back during and after her training sessions.
After two weeks on this regimen, Stephanie came back to me and reported that she felt better during training and had even lost two pounds and one percent body fat. However, she was now feeling especially fatigued in the evening. After giving this information some thought, I came to the conclusion that Stephanie’s body had probably adapted to the poor nutrient timing of her past regimen by slowing her metabolism during and after workouts (that is, by capping her muscles’ rate of energy use), which is probably why she felt lethargic in training. When we started fueling her workouts and recovery processes better, her body started burning all of the extra energy during her training, allowing her to perform better, and during the post-workout recovery period. But this left her in a state of energy deficit during the rest of the day, which is why she lost weight and felt fatigued late in the day.
So, we added the 300 calories back to her lunch and dinner without removing them from the workout period. And what happened? She felt great during her training and all day, in fact, but she lost another two pounds in the next two weeks, as well as another one percent body fat. My final conclusion was that Stephanie had not been able to work to her full metabolic capacity due to poor nutrient timing and a slight but significant energy deficit. Two-years-later she still feels great and remains at 16 percent body fat.
Fatigue is the universal symptom. It may result from literally hundreds of different causes in athletes and non-athletes. But, in otherwise healthy endurance athletes, persistent fatigue coupled with poor workout performance most often indicates one of two problems: overtraining or undernourishment.
Overtraining, or inadequate rest, is more common. Thus, if you begin to experience nagging fatigue and training staleness during a period of increasing training, the first thing you should do is reduce your training for a few days and then try ramping up more conservatively. If the problem does not return, it was surely a matter of overtraining. If it does return, you’re probably running an energy deficit.
When you suspect an energy deficit, your best course of action is the two-step process Paul Goldberg went through with Stephanie. First, make any dietary changes that may be needed to ensure that your body is well supplied with energy for performance during workouts and for recovery afterwards. Ideally, you will eat a full, high-carbohydrate meal four to three hours before your workout and consume a sports drink during the workout. In the first hour after the workout, take in plenty more carbs, a little protein, and fluid for rehydration.
If these changes fail to cure your fatigue completely, try adding slightly more calories to your regular meals, but without ever forcing yourself to eat more than you’re comfortable eating. This measure will definitely put an end to your fatigue, if an energy deficit is indeed its root cause.
Energy needs naturally fluctuate as your training workload changes. Your appetite should automatically adjust for these fluctuations. Research has shown that ultra-endurance athletes, who burn upwards of 5,000 calories, experience a level of hunger that drives them to consume an equal number of calories and thus remain in perfect energy balance without having to think about it. Appetite is intelligent.
An energy deficit is not always a bad thing, of course. If you could stand to lose a few pounds and you increase your training, you will probably experience an energy deficit that will cause you to shed body fat. This deficit will not render you under-fueled for workouts, however, because your shrinking fat stores themselves will make up the energy gap between the calories supplied by your diet and the calories your body burns in workouts and throughout the day.
Even lean, high-level endurance athletes may experience a non-problematic energy deficit of this sort during peak training. A recent study found that a group of Kenyan runners consumed fewer calories than they burned during the final weeks of training before a marathon. This was surely not a matter of under-fueling. Rather, their bodies were simply “choosing” to become even leaner in preparation for peak performance on race day.
Due to the intelligence of appetite, endurance athletes seldom experience the bad sort of energy deficit, unless they strictly control their food intake. So, if you’re a lean, competitive endurance athlete, my advice for you is this: stop thinking like a fat person!
Matt Fitzgerald is editor of PoweringMuscles.com, an online sports nutrition information resource for athletes..