I’m a reasonably intelligent person. I did well at school. I’ve got a degree. I take an interest in science. I’m rational. I tell you this not to boast (okay, maybe a little), but to put in context some of my behaviors. Behaviors that are, to be frank, a bit extreme.
I want to talk about body fat. Specifically, how body fat can affect performance. I’ve come across a spate of articles recently on how body fat can negatively affect performance, particularly in the sprints. The article “How Body Fat Affects Athletic Performance” dates from 2012 but just resurfaced onto my social media feeds. The gist is that small amounts (2 pounds) of additional weight can slow down an athlete. The evidence cited for this conclusion isn’t great. For example, the study “The effects of training history, player position, and body composition on exercise performance in collegiate football players” showing that increases in body fat didn’t significantly affect performances in American football wide receivers or running backs but did in linemen. Another study “Seasonal changes in VO2max among Division 1A collegiate women soccer players” shows that body fat doesn’t change over the course of a season in a university soccer club (I have no idea why this study was even included), and this one, “Influence of upper-body external loading on anaerobic exercise performance” which shows that adding external loads to athletes makes them immediately slower. This shouldn’t be all that surprising. When we put 200kg on our back during a back squat, we generally can’t run all that fast. The difference is that body fat gains happen over time, so the body can better adjust to that increase in weight. As a result, that weight is reasonably well distributed across the whole body, or at least over a fairly large area.
Whenever I see articles like this, I get uncomfortable. I don’t have a particularly positive relationship with body composition, and I question the validity—or at least the real-world application—of some points in the articles.
Let’s take my own experiences. In 2005, I won the European Junior Championships and ran 10.22 for 100m. My body fat was 15%. That’s quite fat, at least for a sprinter. Yet no other sprinter my age in Europe was better than me. Two years later, I had my best competitive season ever, running 6.55 for 60m and 10.14 for 100m. I was 8% body fat. Even though that isn’t that lean, it was still a drastic improvement over my 2005 levels. It correlated quite nicely with improved performance.
However, let me give you two other examples. In 2006, the year after winning the European u-20s and the year before running 10.14, I was 9% body fat. But I ran 10.34 that year. A negative correlation between body fat and performance occurred from 2005 to 2006. In 2010, I was 8% body fat and ran 10.38, my slowest since 2004 when I was 17. So is losing body fat all that it is cracked up to be?
Consider my journey. After winning the European Juniors, I went to University and joined a professional training group. I had my skinfolds done. You are too fat, I was told. Lose weight. I did. This is what I ate:
- Breakfast – small bowl of porridge
- Post-training – protein shake
- Lunch – salad or soup
- Evening meal – 500g turkey stir-fried with an onion, topped with salsa.
This was a horrific diet. And yet it worked. I got leaner, ran well, won medals, everyone was happy. Then the next year, I did the same again….And ran a bit slower. The year after, I added more vegetables to my diet, and also a bit more total food…. And ran slower. Then I worked with a nutritionist to get my diet sorted and get lean….. and I ran slower.
Turns out, losing weight may not be all that beneficial for performance. Food, and in particular carbohydrates, is ergogenic for high-intensity performance. Large amounts of nutrients are also required for recovery. Losing weight is associated with a low-calorie diet, which can lead to under-recovery.
Now, clearly bodyweight—and especially body fat—has the potential to impact performance. In any event where bodyweight is carried, too much has an impact. You should make an attempt to reduce any unnecessary weight. That’s just mechanics.
The thing is, though, athletes aren’t machines. They have feelings, biases, and beliefs. Like it or not, food has a massive social and cultural importance, so the act of reducing body fat can impact athletes. At family meals I’ve been the athlete who is starving but can only eat a salad. It isn’t much fun. This can impact the athlete’s mental well-being. As can always being hungry. And it’s only one step away from an eating disorder.
Finally, consider this: It’s two weeks before a competition, and you have tested your athlete’s body fat. He is 1.5kg above where you want him to be. Is it better for him to undereat by about 10,000kcal in the next two weeks? Or is it better for him to be a bit overweight, but compete with full muscle glycogen stores, a positive mood, and an unimpaired recovery afterward? A good fluid and food intake strategy in the 48 hours leading up to competition can comfortably lose 2kg in weight (although not fat), so why potentially sabotage a good performance?
In conclusion, then, there is a sound rationale for ensuring that body fat in athletes is low. However, it is essential to remember that athletes aren’t robots. They probably like eating food. Everything is a tradeoff; the more weight you lose, the more you may impair recovery or training-based adaptations. Timing is essential, and you should take care to ensure that athletes don’t develop disordered eating habits. Placing a disproportionate emphasis on leanness can lead to a variety of problems. At the end of the day, the bigger picture is important. Athletes should be lean enough to compete well, without chasing excessive leanness at the cost of performance and recovery.
And remember, your emphasis on leanness can affect athletes. I still remember being laughed at by a Great Britain team doctor 11 years ago because he thought I was too fat to be a sprinter. At that point, I was the fastest 17-year-old in the world outside of North America and the Caribbean, and yet it still affected me—and perhaps influenced my eating habits in later life.
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