• Posted July 17, 2024

Starving Pre-Performance Won't Bring Medals: Study

Dropping weight prior to competition is a common practice among athletes.

But starving oneself prior to an intense athletic event is likely a wrongheaded, self-defeating practice, a new study warns.

Triathletes who ate less prior to competition lost more muscle mass and performed poorly, compared to their function after they followed a sensible diet, researchers found.

“There is no doubt that this practice greatly impairs one's performance as an athlete, even over shorter periods of time," said lead researcher Jan Sommer Jeppesen, a doctoral student with the University of Copenhagen in Denmark.

Attempts to lose weight prior to competition might be driven by a belief that fewer pounds will enhance performance, or by a desire to look “lean and mean” when hitting the field, researchers said.

Regardless, it’s a widespread phenomenon among athletes, particularly those in endurance sports like running, swimming, cycling and rowing, researchers said.

"It is particularly problematic among female endurance athletes. Many athletes focus heavily on weight in their respective sports. Consequently, they tend to go into short-term, but intense periods of weight loss with the expectation of performing better," said senior researcher Ylva Hellsten, a professor with the University of Copenhagen’s Department of Nutrition, Exercise and Sports.

But not eating enough is associated with missed periods, compromised bone health, changes in metabolism, and other health effects that could actually hamper an athlete’s performance, researchers noted.

To learn more, the research team recruited 12 female triathletes and had them undergo two rounds of performance testing.

The athletes ate a healthy diet for two weeks prior to the first round of testing, which involved a biking time trial.

For the second round, they cut their calories by 50% for two weeks while maintaining their usual intense training schedule.

The athletes lost about 4% of their body weight during the calorie-cutting phase of the experiment, about half of which was muscle mass, researchers said.

They also performed about 8% worse on a 20-minute time trial, “which is quite significant,” Jeppesen said in a university news release.

“And during a more intense short-term test, their performance slid by as much as 18%,” Jeppesen added.

Worse, the athletes’ performance continued to suffer even after a three-day recovery period where they were provided plenty to eat.

"We had expected that the three days of enough food would restore their performance – and maybe even improve it – but there was absolutely no effect,” Jeppesen said. ”Their performance was just as degraded as prior to the three days. This tells us that the negative effects cannot be reversed by quickly replenishing energy stores, which is a strategy used by many athletes.”

Cutting calories specifically affected the athletes’ immune function, increasing stress on their bodies, researchers found.

“The athletes had a large increase in cortisol, a stress hormone, and a dramatically increased stress level in immune cells,” Jeppesen said. “This suggests that there is a quite severe impact on several aspects of the immune system if one doesn't eat enough. This may potentially contribute to athletes being more exposed to illness.”

This year’s Tour de France in particular has been hampered by disease, with GI illnesses and COVID sweeping through the event.

Researchers hope these results, published recently in the journal Redox Biology, will help raise awareness of the phenomenon, and how counterproductive it can be.

"Many coaches continue to pressure athletes to lose weight. For many years, it has been a part of the culture in the sports world – and remains so,” Hellsten said. “We need to shed light on the phenomenon and ask critically: What are we actually doing to our athletes both physically and psychologically?"

The elite Danis sports organization, Team Denmark, said it plans to act upon these results.

Mary Jorgensen, a sports nutritionist and manager at Team Denmark, said she works with “many athletes who trim their weight in the weeks leading up to a competition, but without understanding the consequences of doing so."

"My experience is that elite athletes and coaches are curious, but need research that backs up any critiques,” she said.

“Here, the fact that the test subjects are actual athletes is a major strength, so that the results can be transferred to the athletes and coaches that Team Denmark supports,” Jorgensen said. “We will use these results to support what we are already trying to communicate, both when we sit down with athletes one-on-one, as well as during workshops and presentations in these types of contexts.”

More information

The University of Washington has more about eating for peak athletic performance.

SOURCE: University of Copenhagen, news release, July 15, 2024