The Fight Against Under-Fuelling: Chasing the Power to Weight Ratio

The Fight Against Under-Fuelling: Chasing the Power to Weight Ratio

Aug 2022
The Fight Against Under-Fuelling: Chasing the Power to Weight Ratio

In this week's article hexis' Head of Performance Science, Dr. Samuel Impey, reflects on his experience working with Pro Peloton cyclists and what it can teach the rest of us about weight loss. 

Chasing Power: Weight 

One day I'd like to meet a cyclist who doesn't want to "lose a bit of weight" - so far in my career, it hasn't happened! It feels like there is always a little extra we can chip away at to improve our body composition and thus improve our Power to Weight ratio (P:W). Everyone understands the benefits of improving P:W, but what is often overlooked is how to do this and what the risks are if we get it wrong. 

RED-S - Ever heard of it? 

Relative energy deficiency in sport (RED-S) is a big problem, especially in endurance sports where the energy turnover is so high. RED-S describes the changes our bodies go through when we are not giving our body enough energy to sustain all the essential physiological functions AND train as hard as we want. If there isn't enough energy - something has to give! 

We can see the effects of RED-S in several different ways, the most common are: 

  • Increased number and severity of illness (picking up coughs and colds easier)
  • Taking significantly longer to recover from training than normal 
  • Increased chances of bone fractures from lower bone mineral density
  • Irregular menstrual cycle, or cycles stopping all together 

These effects can begin to happen when we are trying to lose weight if the energy deficit we create each day is too big, which occurs day after day. The problem when trying to improve our P:W is that quite often, the weight loss bit is done (or tried to be done) too quickly! To get quick results, we create massive energy deficits to lose weight fast - which is understandable because this always feels much easier than doing it slowly over a more extended period. But this is where the problems can begin to occur! Add to that the challenge of improving power per se which takes even longer and more effort; it's no wonder that so often, the answer to how to improve P:W is through "quick weight loss". 

How to lose weight effectively.

The key to effectively losing weight is to do it SLOWLY - unfortunately, this isn't easy as it takes a little effort for a longer period of time. The goal should be to create an energy deficit of 300 - 500kcal per day (a medium latte is ~200kcal) - we are talking about a calorie deficit that you shouldn't even be able to feel. By making small changes to our diet to create small energy deficits, we do not put our bodies under the same level of energy stress that we do with very large energy deficits. This lower stress means our bodies can function normally without the risk of seeing some of the effects discussed above. It's important to remember that on days when we are training for longer or at higher intensity, we need to consume more calories, which is still true when trying to lose weight. We still need to eat more because we are exercising more, but we can still create that small energy deficit for the day. This is called nutrition periodisation. 

Nutrition Periodisation 

To effectively fuel our bodies and achieve our training and body composition goals we need to change what and how much we eat depending on the training we are doing. On days when we have higher calorie needs because our training was long or hard, we need to eat more, and on days where our training was short or easy, we need to eat less. When we do this, we match our body's energy needs that allow us to complete and recover from our training but also provide our body with the energy it needs to keep all our physiological functions working effectively. We do this at Hexis with Carb Coding and our kcal and macro recommendations - translate your training needs into the amount of kcal and food your body needs for the day.  To see the science behind the Carb Coding, check out our Case Study: The Application of carbohydrate periodisation throughout a cycling Grand Tour, which took place during the 2021 Vuelta a España.

To discover more about RED-S and its symptoms, check out our first article in our Fight Against Under Fuelling series, 'Cycling's Secret Epidemic', or checkout the Higher Gear Podcast episode where we spoke to elite runner and Doctor of Exercise Physiology Jess Piasecki to see how hexis can help you avoid RED-S.

David Dunne

David Dunne

Dr. Sam Impey

Performance Scientist

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Dr. Sam Impey