We’re going to start by exploring the physiology relevant to how the body converts food into our most valuable resource of all: energy.
PART 1: FROM FOOD INTO ENERGY
Almost all our energy needs are met through the activity of tiny capsule-shaped structures in our body’s cells known as ‘mitochondria’. Essentially, mitochondria take ‘fuel’ (from food) and convert it into energy. You can think of the mitochondria as tiny engines that drive the processes in the body – everything from our mental energy to the speed and strength of our muscles. Energy production in the mitochondria is dependent on two main factors:
1 How effectively the mitochondria are supplied with fuel
2 The appropriateness of the fuel supplied to the mitochondria
Much of this chapter is dedicated to optimizing these factors to get the best performance out of our body and brain.
There are essentially two fuels the mitochondria can use to create energy. One is sugar; the other is fat. Later on in the chapter we’ll be exploring the role of fat (in all its forms) in the diet, but for now, let’s focus on sugar.
There are different types of sugar in the diet, but the one that the mitochondria utilize to generate energy is known as ‘glucose’. Some foods contain actual glucose, including certain fruits and sugary soft drinks. Glucose can also be derived from ‘table sugar’ (‘sucrose’), which consists of a molecule of glucose joined to a molecule of another sugar known as ‘fructose’.
Another important (but sometimes under-recognized) source of glucose is starch (found in foods such as bread, potato, rice, pasta and breakfast cereals). Starch is, essentially, made up of a chain of glucose molecules.
From Starch into Sugar
Conventional nutritional wisdom tells us that starchy foods such as bread, potato, rice, pasta and breakfast cereals take time to be broken down, and therefore deliver a slow release of sugar into the bloodstream for sustained energy.
We are also usually warned that fat is an inferior source of energy as, supposedly, it ‘burns more slowly’ than sugar. Plus, the official line is that fat is fattening, and certain fats (particularly ‘saturated’ fat found in foods such as red meat, eggs and dairy products) can clog the arteries and lead to heart disease.
It is these essential ‘facts’ that have been the major drivers of the traditional dietary advice for us to eat a low-fat, high-carbohydrate diet, replete with foodstuffs such as wholemeal bread, wholegrain breakfast cereals, rice and pasta, supplemented with fruit and vegetables. This sort of diet, according to official sources, is nutritional nirvana.
The concepts used to support low-fat, high-carbohydrate diets may look utterly persuasive on the surface, but in this chapter you’re going to see how eating this way can actually play havoc with your energy, concentration and sleep. There’s also good evidence that ‘healthy eating’ may even jeopardize your ability to control your weight and keep yourself free from chronic conditions such as heart disease and diabetes. Key to understanding all this is an awareness of the importance of maintaining stable levels of sugar in the bloodstream.
A Question of Balance
Imagine you take conventional dietary wisdom to heart and base your diet on ‘starchy carbs’ such as bread, pasta and breakfast cereals. When you eat these foods the starch in them is broken down into glucose through the process of digestion, which is then absorbed into the bloodstream.
This means that whether we eat sugar, starch, or a combination of both, blood sugar levels rise. In healthy individuals, the body responds to this by secreting the hormone ‘insulin’ from the pancreas. One of the chief functions of insulin is to facilitate the uptake of glucose from the bloodstream into our cells where it can be ‘burned’ in the mitochondria to generate energy. It could be said, then, that blood sugar stability is key to ensuring sustained levels of energy. The figure below represents relatively stable blood sugar levels after eating over a few hours.
However, imagine for a moment we eat a food that releases substantial amounts of sugar quite quickly into the bloodstream. In response, the body will tend to secrete copious quantities of insulin. Gluts of insulin are not good news for the body in the long term (see below). Even in the short term, though, surges of insulin risk pushing blood sugar levels down to ‘subnormal’ levels (termed ‘hypoglycaemia’) some time later.
When sugar levels dip too low, our cells can end up seriously under-fuelled, compromising their ability to function optimally. Here are some of the problems that can ensue:
Fatigue and lethargy
Sugar tends to provide ready fuel for the body and if supply stalls, so can energy. Blood sugar imbalance can manifest as fluctuating energy during the day, with the mid to late afternoon being a common low point. The slump of energy that many people experience at around 3 or 4 p.m. is almost always rooted in this issue.
In the corporate arena, I find this one of the most frequent drains on productivity of all, and I estimate it affects about 60 per cent of people to a significant degree. If you have come to recognize that the mid to late afternoon is typically your least productive time of day, then there’s a good chance you have some blood sugar balance issues going on.
Some people are so badly affected by this that they have to pinch themselves under the desk in meetings (or stand on their own toes in operating theatres) to stay awake and alert. One senior lawyer once told me he could be so sleepy in afternoon meetings with clients he would sometimes resort to jabbing himself in the hand with a sharpened pencil. If someone is having to inflict pain on themselves to stay awake in front of a valued client, it’s usually a sign that something is seriously wrong.
Loss of concentration and mental sluggishness
The brain is only about 2 per cent of our weight, but it uses about a quarter of the sugar in the body at rest. In other words, the brain is one sugar-dependent organ. If it’s not adequately fuelled, it tends to malfunction. Common ways this plays out include poor concentration, loss of focus, and a mind completely devoid of fresh ideas and inspiration.
Brain Drain
While facilitating a wellness programme for a group of partners in a financial services firm, one of the delegates recounted a story that aptly demonstrated the hazards of low blood sugar with regard to brain function. He had travelled to a regional office to give a presentation to a large group of colleagues in the late morning. When he got up to speak, though, ‘gibberish’ (in his own words) came out of his mouth. He composed himself, started again, but the result was the same.
He excused himself and recommended that everyone reconvene in ten minutes. During that time he