Is Atkins for runners? The truth about carbs and protein

The way things are going, it won't be long before Atkins and anti-Atkins replace liberalism and conservatism as the dominant, competing ideologies in this country.

I'm referring of course to the high-protein, low-carb diet promoted by the late diet guru Robert Atkins, and to the backlash against it.

All of this controversy about carbs and proteins has led many runners to question whether the high-carbohydrate diet traditionally recommended for runners is really the right way to go.

Should we be filling up on proteins instead? The purpose of this article is to clarify for you what the latest science says about the roles of carbs and protein in the life of a runner.

No Atkins for runners

While carbohydrate continues to be demonized in the popular media coverage of fad diets, the evidence in support of high-carbohydrate diets for endurance athletes continues to accumulate.

As everyone knows, the Kenyans are considered to be the best distance runners in the world. While the traditional Kenyan diet -- lean, unprocessed, and mostly vegetarian -- is certainly not the only reason behind the Kenyans' running dominance, it is very likely a strong contributing factor.

Recently, researchers from the University of Copenhagen set out to determine the macronutrient breakdown of this diet. They studied the food intake of 12 adolescent male runners from the storied Kalenjin tribe over a two-week period. They found that a whopping 71% of their daily calories came from carbohydrate, only 15% from fat, and a mere 13% from protein. Their staple foods were corn and kidney beans.

One of the main effects of endurance training is that it increases the muscles' capacity to store carbohydrate for use during activity. A high-carbohydrate diet is required to take advantage of this adaptation.

Dozens of clinical studies have demonstrated that the more carbohydrate an athlete has stored in his or her muscles prior to exercise, the better he or she will perform.

For example, in a study performed at the University of Guelph, Ontario, well-trained women were randomly assigned to either a high-carbohydrate (78%) or a low-carbohydrate (48%) food prior to a cycling test to exhaustion. The women in the high-carbohydrate group were able, on average, to continue significantly longer.

Runners do need more protein in their diet than sedentary individuals, due to the need to replace muscle proteins broken down during workouts and races. But they only need more protein in proportion to their overall need for more calories in general.

Protein should account for about 15% of calories consumed. Carbohydrate should account for 60% and fat for the remaining 25%.

Carbohydrate-protein synergy

What tends to get lost beneath the clamor of the pro- and anti-carb and protein ideologies is the important fact that carbohydrates and proteins actually cooperate to boost endurance during exercise and recovery after exercise.

It's not that one is good and the other bad. We need both, and we need them together, to optimize running performance.

Carbohydrate is the primary fuel source for running. As you probably know, a whole mountain of research has demonstrated that consuming a sports drink containing 6 to 8 percent carbohydrate plus electrolytes during workouts and races improves performance and delays fatigue.

For the past 30 years, sports drink formulas have been based on this research. But newer research has shown that consuming a small amount of protein with carbohydrate during exercise results in faster delivery of carbohydrate to working muscles. This is because both protein and carbohydrate stimulate insulin, the hormone whose job is to transport carbohydrate into the muscle cell.

Runners generally fatigue when the working muscles' supply of stored carbohydrate (called glycogen) becomes depleted. So, the faster the carbohydrate you consume during a run is delivered to the working muscles, the more glycogen is conserved and the more fatigue is delayed.

In one study, athletes who used a carbohydrate-protein sports drink were able to continue 24% longer than athletes who used a conventional carbohydrate-only sports drink, and 57% longer than those who drank only water.

During prolonged runs, when carbohydrate fuel runs low, as much as 20 percent of a runner's energy needs are supplied by protein. Under normal circumstances, these proteins are "stolen" from muscle tissue. This process weakens the muscles, reducing performance, and leads to post-exercise muscle soreness.

However, there is evidence that consuming protein can reduce muscle protein breakdown -- and the weakness and soreness that come with it -- during prolonged exercise. By using a sports drink or energy gel containing protein, you are able to get the majority of the protein your body needs for energy from this source, so your muscles are left alone, and both your performance and your later recovery get a boost.

Getting the right amount of protein is crucial. Exercise physiologists believe that a carbohydrate-protein ratio of 4 to 1 (that is, 4 grams of carbohydrate for each gram of protein) is optimal. When greater amounts of protein are taken in, the rate of stomach emptying decreases and gastrointestinal problems (e.g. stomach cramps, nausea) can result.

After exercise

It is not possible to consume enough carbohydrate during moderate- to high-intensity exercise to replace what is burned, nor to completely offset muscle protein degradation. So it is important to consume additional carbohydrate and protein after the workout.

This should be done as soon as possible, because the body is able to synthesize glycogen and protein at more than twice the normal rate due to heightened insulin receptivity in the muscle cells following exercise.

Carbohydrate-protein sports drinks are again the best immediate post-workout nutrition source because of their rapid absorption and their water and electrolyte content. Using such drinks and/or water and solid foods, you should be sure to fully replenish fluid losses (i.e. return to pre-workout bodyweight) and consume 10% - 20% of your daily carbohydrate and protein intake within the first two hours after completing exercise.

Action steps

Chances are you're already eating more than enough protein. Chances are, too, that you're getting less than 60% of your calories from carbohydrate. To find out, record everything you eat and drink for a three-day period, and use a resource such as The Complete Book of Food Counts or similar book to determine the macronutrient breakdown. Then tweak your diet as necessary.

It's also likely that you're not consuming carbohydrate with protein during workouts. The simplest way to correct this problem is to switch to one of the newer sports drinks that contain the ideal 4:1 ratio of carbs to protein.

Your body will let you know you're doing the right thing. Then you can tune out all that fad diet noise!

Copyright 2002 by Poweringmuscles. Published with permission. For cutting-edge sports nutrition info, visit

Matt Fitzgerald coaches runners and triathletes online through Carmichael Training Systems ( and is the author of "Triathlete Magazine's Complete Triathlon Book."

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