July 01, 2022 6 min read
Renee McGregor, leading sports dietitian and author of More Fuel You, discusses the complexity and misconceptions surrounding sports nutrition, and offers her top tips for maintaining a healthy approach to nutrition.
Nutrition is one of those topics that’s always going to be controversial because everyone has an opinion on it and it’s not always clear cut. While nutrition is a science and an evolving one at that, it is not absolute. How can that be when we are looking at the impact it has on the human body? While the general anatomy and physiology of a human is understood, there are also huge variations between us all due to genetics, lifestyle, ethnicity and gender, which is why advice tends to be ballpark and it is clear that humans are not textbook!
Photo © Tim Lloyd
However, it is not necessarily the science that makes nutrition so confusing but the poor understanding and delivery of it. As someone who works across both clinical and sports nutrition, one of my biggest complaints is how those working in sports science ignore the clinical mechanics of the human body, while those working in clinical don’t appreciate important and relevant findings from sports science. Indeed, there are very few practitioners working across both fields that are able to bridge that gap.
While many working in the nutrition field simply look at the impact of one particular nutrient or process on performance, this completely ignores the fact that the human body is a series of chemical reactions resulting in the intricate system of endocrine, biochemical, immunological, physiological and psychological pathways that all work collectively.
If we take this one step further, sports science is further flawed by the fact that most research is done on white, well-trained, men. Can we really use this data for all of us who belong to the population of individuals that are physically active?
Let’s take the keto diet as an example. This was a huge trend a few years ago and many still promote it with the idea that if we remove carbohydrate from our diet, then our body will use more fat for fuel and improve our performance and also our body composition. While on the surface this may seem to have some gravitas, if you take out carbohydrate, then the body will have to find another source of fuel. However it completely ignores the fact that carbohydrate is actually required to provide the energy to use fat for fuel.
Even more importantly, carbohydrate is critical for the correct functioning of the hypothalamic pituitary axis (HPA). The HPA controls all the hormonal processes within the body so if this doesn’t work optimally, then neither does your body. So while you may be putting the right training stimulus into your body, if you do not provide it with the relevant fuel, namely carbohydrate, it prevents the hormonal cascade that is required in order for adaptation from the training response. In addition, female bodies are much more sensitive to this decrease/removal of carbohydrate in their diets and will see the negative consequences a lot sooner than males, who are still at risk.
Photo © Calum Maclean
Similarly, it has been well documented that carbohydrate plays a central role in maintaining optimal immune function, particularly in those who are physically very active. If you limit your carbohydrate, especially around a high training load, you can depress your immune system and increase your risk of infection.
So why do these trends gain momentum?
One explanation seems to be that fewer people trust their bodies and are instead always looking to external cues for information on how to eat, train and live. With the rise in technology and the ability to measure pretty much every aspect of your life on your smart phone and sport tech, we no longer seem to tap into our internal cues. And yet the body probably has the most sophisticated form of monitoring, homeostatic control.
Photo © Tim Lloyd
The body works on a number of feedback loops that helps to ensure our temperature stays stable and our blood levels of key nutrients such as sodium, calcium and potassium remain within appropriate limits. In fact, this is why it is so important that you maintain a good nutritional source of calcium in particular. Calcium is important for a number of functions including muscle contraction. If blood calcium levels drop, the body identifies this and sends a signal; this then causes calcium ions to be released from our bones in order to maintain blood levels. However, if you don’t provide your body with sufficient dietary calcium, then you don’t replace this in the bone, making it weaker.
This is one of the key reasons I really dislike the use of food tracking apps because how can an app truly track something as complex and brilliant as the human body? How can it know whether the body needs more energy today to make red blood cells? Or repair tissue damage? Or even respond to a change in hormone levels in women during their menstrual cycle?
That being said, not all monitoring and technology is bad; it can be useful to understand how your body is responding to training and lifestyle stress by tracking your heart rate variability (HRV). Equally, using blood biomarkers to help measure immunity, metabolism and inflammation can help educate your next training move.
Another area that we all need to be mindful of is social media. Social media is flooded with pretty pictures of food, enticing us to eat in a particular way, creating identities around how a “healthy diet” is perceived. We buy into it because it suggests a “false gold” of success and achievement, but what if this is not what our body actually needs?
For example, while we should definitely be trying to eat more plant-based foods and include a variety of colours in our daily intake, this doesn’t translate as ‘we must all become vegan’.
Photo © Steve Ashworth
In fact, a vegan diet may not be appropriate for those of us who are active, training for an hour a day, at least four times a week, with high energy and carbohydrate requirements. Presently there is no scientific evidence to suggest that a plant-based diet can improve an individual’s performance. If anything, there is more evidence pointing at the opposite; that a plant-based diet can be lacking in sufficient energy and also specific nutrients needed to improve performance.
Indeed, a common mistake is that many people view vegetables as carbohydrate, often displacing these for pasta, grains, bread and potatoes. While vegetables play a role within our diet and should be included, they are predominantly fibre which means they add bulk to the diet but not essential carbohydrate fuel. Thus, a plant-based diet, if not managed well, can actually limit your intake of overall energy, which in turn can have negative consequences on performance, recovery and health.
Photo © Tim Lloyd
So how do you navigate your way through the abundance of information available on nutrition? Here are five top tips:
(1) Don’t be drawn to the latest fad. Many athletes will try almost anything to improve their performance. Focus on training, sufficient rest and getting the building blocks of your diet correct first.
(2) After a very hard training session, take on a recovery choice that is easily digestible within thirty minutes of finishing your run (especially if you will be training again within twelve hours). Flavoured milk is a good example; the combination of added sugar to the natural milk sugar causes insulin to increase in the blood. Contrary to what you might think, this is actually really important. Only when our insulin levels are raised can we draw carbohydrates and protein into the muscles to start the recovery process.
(3) Always practise your competition day nutrition. The worst mistake you can make is to use what is available on competition day without previously having tried it; this could have real negative effects on your performance.
(4) Work out what is right for you. Remember N=1 is not science; just because your training partner swears by a bowl of porridge every morning, this doesn’t necessarily mean it’s the right fuel choice for you.
(5) You don’t have to eat less on your rest day. For most, this will fall between two training days, so it is the perfect opportunity to recover and then refuel. By being consistent with your nutrition, you will also allow for consistency with your training, which allows for progression.
More Fuel You, Renee’s guide to sports nutrition, is available to order now
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