Nutrition is one of those topics that is always going to be controversial, just like politics because everyone has an opinion on it and also, it is not always clear cut. While nutrition is a science and an evolving one at that, it is not absolute.

How can it 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 N definitely doesn’t equal 1.

Nutritional science, particularly sports specific, is actually quite complex. While many simply look at the impact of one particular nutrient or process on performance, this completely ignores the fact that the human body is run on an intricate system of endocrine, biochemical, immunological, physiological and psychological pathways that all work collectively.

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 but also our body composition. While on the surface this may seem to have some gravitas; take out carbohydrate and so 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.

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 few people seem to trust their bodies anymore, instead they are 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 watch, we no longer seem to tap into our internal cues. And yet, the body probably has the most sophisticated form of monitoring, homeostatic control. The body works on a number of feedback loops that helps to ensure that our temperature stays stable; 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 do not provide your body with sufficient dietary calcium, then you do not 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 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 HRV, heart rate variability. 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 and include a variety of colours in our daily intake, this doesn’t translate as,

“We must all become Vegan.”

In fact, for those of us who are active, training for a hour a day, at least 4 times a week, with high energy and carbohydrate requirements, a vegan diet may not be appropriate. Presently there is no scientific evidence to suggest that a plant based diet can improve an individual’s performance; in fact 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, due to being highly volumous can actually limit your intake of overall energy, which in turn can have negative consequences to performance, recovery and also health.

So how do you navigate your way through the abundance of information available on nutrition?

written by

Renee McGregor

Sports and Eating Disorder Dietitian from Bradford-O-Avpn

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