Written by Teemu Virtanen (research analysis on Science Daily)
There are many different diets available for people who are looking for healthier lifestyles, losing fat and even getting in shape when aiming to do well in any sport. In endurance sports, eating carbs and various carbo-loading methods have been common among the athletes doing races that last several hours.
But there is also another school of thought that says low carb diet is the key to success. I, for one, have been on a low carb diet for years eating only carbs just before my long distance (and ultra distance) performances. And my results have been quite satisfactory. Now, there is even evidence, scientific research, to prove that indeed eating little carbs can burn more fat than the usual carbohydrate rich diets.
When researching the topic, I found an interesting study conducted in America, which may make you re-consider your eating habits. As we are now at the tail end of our season and we have two really challenging races left in Visma Ski Classics and some of our skiers, myself included, are going to do the toughest ski race in the world, Red Bull Nordenskiöldsloppet, 220 km on Saturday, it may be useful to peruse this research quite thoroughly as you may find it quite enlightening. It was originally published online in the journal Metabolism: Clinical and Experimental.
Elite endurance athletes who eat very few carbohydrates burned more than twice as much fat as high-carb athletes during maximum exertion and prolonged exercise in a new study — the highest fat-burning rates under these conditions ever seen by researchers.
The study, the first to profile elite athletes habitually eating very low-carbohydrate diets, involved 20 ultra-endurance runners age 21-45 who were top competitors in running events of 50 kilometers (31 miles) or more.
It can take weeks or longer for the human body to fully adjust to a ketogenic diet, so the low-carb athletes in the study were eligible only if they had been restricting carbs for at least six months. Their average time on a ketogenic diet was 20 months.
The 10 low-carb athletes ate a diet consisting of 10 percent carbs, 19 percent protein and 70 percent fat. Ten high-carb athletes got more than half their calories from carbs, with a ratio of 59 percent carbs, 14 percent protein and 25 percent fat.
In all other respects, the athletes were similar: elite status, age, performance, training history and maximum oxygen capacity. They all had the same engine, so to speak.
Scientists measured gas exchange repeatedly during a test determining the athletes’ maximum oxygen intake to gauge carb- and fat-burning rates. On average, the low-carb runners’ peak fat-burning rate was 2.3-fold higher than the rate for high-carb athletes: 1.5 versus .67 grams per minute.
Over two days, researchers subjected the athletes to tests to determine peak fat burning during a brief high-intensity workout and metabolic characteristics during prolonged exercise.
On day one, the athletes ran on a treadmill to determine their maximum oxygen consumption and peak fat-burning rates. On day two, the athletes ran on a treadmill for three hours at an intensity equal to 64 percent of their maximum oxygen capacity. During this test, they drank water but took in no nutrition — before the run, athletes consumed either low- or high-carb nutrition shakes consisting of about 340 calories.
During the endurance run, the two groups did not differ significantly in oxygen consumption, ratings of perceived exertion or calorie expenditure. However, fat-burning rates during prolonged exercise were again about twice as high in the low-carb athletes, and the average contribution of fat during exercise in the low-carb and high-carb groups was 88 percent and 56 percent, respectively.
One key finding: Despite their low intake of carbs, these fat-burning athletes had normal muscle glycogen levels — the storage form of carbohydrates — at rest. They also broke down roughly the same level of glycogen as the high-carb runners during the long run, and synthesized the same amount of glycogen in their muscles during recovery as the high-carb athletes.
As you can see, the results were quite astonishing, and the lead researcher Jeff Volek, professor of human sciences at The Ohio State University, was willing to go as far as to say that we should perhaps re-evaluate our carbo-loading teachings.
“These low-carb athletes were spectacular fat burners. Their peak fat burning and the amount of fat burned while running for three hours on a treadmill was dramatically higher than what the high-carb athletes were able to burn. This represents a real paradigm shift in sports nutrition, and I don’t use that term lightly. Maybe we’ve got it all backwards and we need to re-examine everything we’ve been telling athletes for the last 40 years about loading up on carbs. Clearly it’s not as straightforward as we used to think.”
Certainly, this provides food for thought while we prepare ourselves for the final races of the season. It may be a bit too late to hop on the “Atkins diet” bandwagon for this season, but perhaps some of you may want to try it out over the summer and see if it really makes a difference.
