YOUR BREAKFAST MIGHT be a couple of poached eggs, golden yolks spilling slowly on to rich green avocado, freckled with chilli and mint, all sitting atop a slice of sourdough bread, in your favourite café – deliciously Instagrammable. It might be a humble bowl of cornflakes at your kitchen table, doused in semi-skimmed milk and awaiting that first reassuringly crunchy bite. Or it could simply be a slice of toast in your hand as you race out the door to catch the train. You might even choose to skip breakfast altogether, going for a run first thing and then hopefully grabbing something on the way in to work.
But no matter what it is, and no matter how aware of it you are, this is how your engagement with energy for the day begins. Whether you’re conscious of it or not, you are already making decisions that will have an impact on your energy in both the near future – later this morning, afternoon or evening – and the longer term – the habits that will continue tomorrow, the impact on your body in the coming days, weeks, months and years.
Performance nutrition is about making strategies to improve your energy levels – whether that’s at work, in your fitness regime or at home – and instilling the know-how and habits so that you can sustain your progress. Part of my role as a sports nutritionist is to educate, and while some of my clients – whether elite athletes or active businessmen and women – come to me with a good working knowledge of their body and how it uses food to produce energy, for many others biology lessons from school seem like a long time ago and their understanding might not be so clear.
Too much nutritional advice today tries to dazzle, with expressions like ‘metabolic’, ‘antioxidants’ and ‘phytonutrients’, but without a basic grasp of how our bodies work, we can’t fully understand how nutrients are used as fuel, meaning that each new piece of nutrition information we hear or read just layers on more confusion.
That’s why I like to start by getting back to basics: looking under the bonnet of these high-performance vehicles we all walk around in every day.
Whether it’s eggs and avocado, cornflakes or a slice of toast, your body, unlike your Instagram followers, won’t discriminate: they’re all sources of energy that will propel your body and mind through your day. And, as you bite into that initial mouthful of food, energy’s journey begins in earnest.
As you chew you are increasing the surface area of food for the benefit of digestive chemicals called enzymes, which break food down into particles small enough to be used by the body. Some of the key micronutrients (vitamins and minerals, which we’ll discuss in more detail in Chapter 2) from fruit and vegetables, such as dietary nitrates from beetroot, begin a crucial part of their digestion in the mouth.
The mouth also contains receptors that link to the brain’s pleasure and reward centres. Research has shown that endurance athletes get a performance boost simply from using carbohydrate as a mouthwash and spitting it out, without needing to swallow and digest in the traditional manner – about as quick an energy shortcut as you can imagine.1
When you swallow your food, it travels down the oesophagus and into the stomach, which releases more digestive enzymes and acid to help break down the food, and to sterilise it all. The stomach acts as a short-term store and gradually passes the broken-down food to the intestines, where the digestive process will be completed.
The small intestine – it’s actually about six or seven metres long, depending on the individual – with some help from the liver, finishes breaking down the food so that it’s now made up of molecules ready for the body to use. These digested food molecules then pass through the wall of the small intestine to the liver for further processing and into the bloodstream. Once the small intestine has finished this process, what is left passes through the large intestine, which absorbs the water and electrolytes – and I’m sure you’re familiar with how this particular story ends… when you sit down on the toilet.
This system, one long, uninterrupted line that begins with your mouth and ends with your large intestine, is called the gastrointestinal (GI) tract. We will discuss your gut (or GI) health later in the book, when we talk about immunity.
In the meantime, however, your energy, which started life as your breakfast, is now in your blood, and its journey is about to get a lot more action-packed.
Performance nutrition has been adopted in Formula 1 motor racing in recent years. I must confess that I’m not much of a petrolhead but the motor car does offer a good representation of the human body and our relationship with food.
The process I’ve just described is digestion, in which we take food and break it down into smaller parts, first with our teeth and then with our small intestine, so that it exists in a currency our body can use. The Energy Plan approach is that food is fuel, and the process of eating and digestion is like fuelling our engine at the petrol station. Our metabolism, which is the next state of this process, is the car engine. It takes its fuel, in the form of digested food, and turns it into energy to support the body’s maintenance – the growth and repair of organs and cells – and movement. Your walk to work, your morning HIIT class, even your immune health – they’re all thanks to your metabolism. Making sure that you have taken on enough fuel for your bodily functions and your day’s activities, so that you’re not underfuelled and in energy deficit, or overfuelled and with an energy surplus, is the key to achieving an energy balance. You don’t want the fuel gauge to be reading ‘empty’ by 4pm, just as you don’t want to feel like you’ve packed the trunk too full through constant overfuelling.
With your fuel now in the bloodstream thanks to the digestive process, it can circulate in the body’s useable currency: protein broken down into amino acids, carbohydrates in the form of glucose, and fat as fatty acids, all of which we’ll discuss in more detail in the next chapter. Water, vitamins and minerals do not need breaking down in the same manner as their molecules are already of a suitable size for the intestines to absorb.
Your cells take up this fuel and use it to create adenosine triphosphate (ATP), which is the main energy currency of the body and the only one organs like your brain really trade in. ATP is the currency of choice for your muscles and, in essence, for the Energy Plan.
Our body contains different types of muscle: skeletal muscle, which powers voluntary movements like walking or picking something up; cardiac muscle to pump blood from the heart; and smooth muscle, which coordinates the involuntary movements of organs like the stomach and intestines. All of these types of muscle require an expenditure of energy.
Within all the types of muscle cells there are a host of power generators called mitochondria. These take fuel and convert it into ATP, which powers your body’s needs: movement, cell growth and repair and cognitive function. We’ll return to these power generators later in the book, in Chapter 2, as they are something we can exercise some control over with our Energy Plan; they can have a positive effect on goals like losing body fat.
Your skeletal muscles contain some intricate architecture to help you move, just as a car contains the requisite man-made mechanics to power its movement. In the body’s case, this involves using ATP to power the muscles to contract, which creates movement.
We will reference energy’s journey and the various important aspects of our body, such as the mitochondria, throughout the book, so it might be useful to refer back to this chapter later. What is important to grasp now is the idea that your body is an engine, and it uses food as fuel to power all of its functions, from cellular activity through to movement.
With the athletes I work with, we don’t talk about being on ‘diets’ or anything that suggests a short-term fix before returning to a status quo. Instead the athletes are on constantly evolving Energy Plans, which are flexible and can be changed to meet the demands of the day, or a longer period of time, such as a week or a season. They might run an energy deficit for a while to achieve a goal, but they will then adjust to another form of Energy Plan. There is never a sense of being ‘finished’; the Energy Plan is a sustainable way of life.
It’s important for me to emphasise that I want you to think about food in a positive way. No matter what you eat, whether it’s the picture-perfect poached eggs and avocado or the bowl of cornflakes, it all makes the same journey we’ve just outlined, even if its constituent parts might have very different effects. Food is fuel, of course, but it also has the capacity to be elegant, enticing and aspirational; it can be warming, reassuring and comforting; and it brings people together as the centrepiece of some of the biggest and most important moments of our lives, such as weddings, birthday parties and first dates – or as a takeaway in front of the television with your friends or loved ones.
I want to be clear now that the Energy Plan isn’t about depriving you of the food and drink you love. It’s about giving you the tools to understand your intake and be able to tailor your food to meet your goals. Better nutrition starts by increasing the variety of foods in your diet, not restricting, to deliver the full spectrum of nutrients each day. In my own Energy Plan I still find room to enjoy a burger. If I meet a client in a café, I have a coffee (flat white, please – ‘extra hot’ is my only higher-maintenance request). And I also think, if you’re going to put so much dedication into living well for the majority of the time, you deserve to treat yourself from time to time.
But it is important to be aware of the constituent parts of the body’s fuel, so that you know exactly what you’re ‘filling up’ with and how this will affect you throughout your day. Our body is both an engine and a very clever currency exchange system, which takes the parts of food and breaks them down into different currencies, several times over, to deliver our body’s needs. So, now that we have a sense of energy’s journey, let’s take a look at the fuels we have at our disposal to best keep our engine ticking over.