As we get older, we often feel as though we have less energy. Is this a natural part of aging or can we change this? Yes, we can absolutely change this with a well balanced, nutritious diet, regular exercise and a positive mindset. However, we can only operate efficiently within our energy budget. Energy is finite and if we overspend, then just as with a bank account, we'll go into overdrawn territory and there is a price to pay for that. Energy can be viewed as the currency of our lifeforce so we need to manage this like we manage our financial budget.
We've all had days where we feel lethargic and tired and days when we are full of energy. What makes the difference between days like this? There are a lot of factors that impact our daily energy levels including poor diet, lack of sleep, lack of physical exercise, too much physical exercise, too much stress, lack of purpose and so on.
Energy Utilization in the Human Body
The human body is an amazing energy conservation machine. The energy in the food we eat is converted into physical activity, bodily functions, thermal energy and stored fat. How this energy is utilised is dependent on how much we eat and how much physical activity we do. If we consume more calories than are required to keep our bodies running, stay warm and to fuel our physical activity, those excess calories will be stored as body fat.
All bodily functions, from thinking to lifting weights, require energy. Digestion of your food requires energy, the beating of your heart requires energy, even sleeping requires energy! The brain uses up to a whopping 20 percent of our total energy. If we assume an average resting metabolic rate of 1,300 calories, then the brain consumes 260 of those calories for synaptic activity and just keeping things going. Glucose is virtually the sole fuel for the human brain, except during prolonged periods of starvation. The brain does not have its own fuel store so it requires a continuous supply of glucose.
Our muscles use glucose and fatty acids for fuel. Muscle differs from the brain in that they can store large amounts of glycogen. In fact, about three quarters of all the glycogen in the body is stored in the muscles. The heart muscle functions almost exclusively aerobically, as evidenced by the density of mitochondria in heart muscle. Moreover, the heart has virtually no glycogen reserves. Fatty acids are the heart's main source of fuel, although ketone bodies as well as lactate can serve as fuel for heart muscle.
The kidneys require large amounts of energy to work optimally. Although constituting only 0.5% of body mass, kidneys consume 10% of the oxygen used in cellular respiration. During starvation, the kidney becomes an important site of gluconeogenesis and may contribute as much as half of the blood glucose. The liver is essential for providing fuel to the brain, muscles, and other peripheral organs. Indeed, the liver, which can be from 2% to 4% of body weight, is the metabolic hub in our bodies. Most compounds absorbed by the intestine first pass through the liver, which then regulates the level of many metabolites in the blood. As we can see from this, the body requires a substantial amount of energy to keep everything running smoothly and to keep us warm. We get this energy from the food we eat which has to be broken down in to the biomolecules that sustain life.
Metabolism is the chemical processes that occur within a living organism in order to maintain life. It is a collection of chemical reactions that takes place in the body's cells to produce energy. There are thousands of metabolic reactions happening at the same time, which are all regulated by our bodies to keep our cells healthy and working.
Metabolism can be divided into two categories:
Anabolism is necessary for growth, maintenance and repair of tissues where as catabolism is necessary for energy production. Catabolism and anabolism occur simultaneously all of the time but they differ in magnitude dependent on your level of activity level, rest and the food you’ve eaten recently. When anabolism exceeds catabolism, we get net growth, but when catabolism exceeds anabolism, we get a net loss and body tissues are broken down. A healthy metabolism needs many nutrients for optimal function and indeed, the antioxidants and phytochemicals discussed in this book can have an anti-catabolic state and increases anabolism which is beneficial for faster recovery from strenuous training and higher levels of performance.
The Metabolic Set Point & BMR
The body seeks to maintain a certain base rate of metabolism which is known as the metabolic set point. It is the average at which your metabolism runs. This results in the basal metabolic rate (BMR) which is the total energy conversion rate of a person at rest. The metabolic set point is controlled by your genetics and environmental factors but it can be changed through diet and training. People with a slow metabolism seem to store fat more easily whereas people with a fast metabolism seem to be able to eat whatever they want and not store fat. Research shows that when a person goes on a low calorie diet, the body’s metabolic set point lowers in order to conserve energy, which makes it more difficult to lose weight. This is the reason that so many dieters hit a plateau and progress halts.
Managing Our Energy
Without managing and optimizing our energy levels, we can feel tired, lethargic and unmotivated. Rather than heading to the gym or out for a walk, its easier to head for the sofa! When we are tired, it is easier to make poorer diet choices as convenience offers an easy way out. Therefore, I think it is important to manage and opimise our energy levels and watch out for those dietary or lifestyle choices that rob us of energy. Lets take a closer look.
Poor Diet & Nutrition
Eating the wrongs foods is clearly not going to provide the high quality energy that we need to get us through the day, let alone doing some physical exercise. In fact, some foods rob us of energy and can make us feel sluggish and lethargic. We could write a whole book on the subject of diet and energy but for now, lets just cover the basics. We’ve already discussed the glycemic index and this is key to getting sustained energy from our foods. Consuming high glycemic foods cause our blood glucose to spike leads to peaks and troughs in our energy levels. Have you ever had a snack or a meal that made you feel more hungry and feeling fatigued a few hours later? This is a phenomenon called ‘rebound hypoglycemia’ which occurs when a high glycemic meal of food is eaten. This causes blood sugar and insulin to spike and subsequently, the blood sugar will then drop below levels before the meal leaving you hungry and fatigued. This opens the door to eating more sugary snacks or drinking caffeine beverages to restore energy levels and the cycle starts again. This is not good for our energy levels and over time, can lead to insulin resistance.
Some foods just don’t digest very well and if this is happening, in addition to the digestive discomfort we feel, we are not converting those foods to energy very efficiently. We are using energy to fight the digestive battle that is going on. I know that there are certain foods that really give me indigestion and make me feel sub par. I generally steer clear of these foods. If you have a lactose intolerance, then you’ll no doubt have experienced the bloating and discomfort that comes with consuming over your quota of milk. This kind of discomfort doesn’t motivate us to go for a run!
Looking After Our Digestive Systems
Eating should not be taken for granted. The proper digestion of food requires developing good eating habits. For some people, there are foods that just do not agree with them and as a result, they get indigestion, heartburn, bloating, stomach pain and cramps. If a particular food is having this effect on you, it is time to say farewell to that food.
There are certain foods that I like, but unfortunately, they don’t like me for some reason. I have a lactose intolerance and can only digest so much milk. If I have over my quota for the day, then I’m in trouble! I like spicy foods too, but if I overdo it with the chilli peppers, then, I know about it. Cucumber is another one that gives me indigestion, which is a shame, because I like cucumber in a fresh, crisp salad. One might think, what could possibly be in cucumber that gives you indigestion? It is a substance known as cucurbitacin that can cause indigestion in some people. So you have to listen to your body and take appropriate action.
To get the most mileage out of your meals the following points should be considered.
Dehydration can affect our energy levels and mental clarity through the day. Mild dehydration is defined as approximately 1.5 percent loss in normal water volume. Dehydration can have a range of effects upon the body including:
There may be other longer term health problems that are caused by dehydration:-
A recent study, published in the British Journal of Urology, stated that increasing water intake can reduce risk of kidney stones. During athletic events, intense aerobic sessions or heavy workouts, particularly in hot weather, it is not uncommon for athletes to lose 6–10% of body weight in sweat loss. Decreases in physical performance in athletes have been observed under much lower levels of dehydration, as little as 2%. Even under relatively mild levels of dehydration, individuals doing rigorous physical activity will experience a decrease in performance related to reduced endurance, increased fatigue, reduced motivation, and increased perceived effort.
Relying on thirst alone, might not help us to avoid dehydration as the process may have already started by the time our bodies get to telling us about it. How much water should we be drinking to avoid dehydration? There are all sorts of claims out there on this topic and this can be a confusing topic. We get a lot of water from the food we consume so it really does depend on the types of food we are consuming as to how much additional water we need on top of this.
Caffeine also acts as a diuretic, which means that it makes your body lose water so drinks with caffeine will negatively impact your water intake. A study published in the European Journal of Epidemiology found that water loss due to caffeine corresponded to 1.17ml per mg of caffeine. This works out at a loss of nearly 164ml of water per mug of filter coffee based on a mug containing 140mg caffeine.
This same same study found that alcohol causes a water loss of 10ml per gram of alcohol. Therefore, for a large (250ml) glass of wine of average strength (13%) The alcohol content of the glass is 32.5ml, which equates to 25.6g of alcohol. This means that the body will lose 256ml of fluid, which is a higher volume than the glass of wine itself!(498)
Your level of exercise will also affect your requirement for water, particularly in the summer months. Therefore, recommended daily water intake is going to very from person to person. There are many different opinions on how much water we should be drinking every day. The health organizations generally recommend eight 8-ounce glasses, which equals about 1.82 liters. This is called the 8×8 rule and while there is no clinical evidence to support this, it is easy to remember.
The European Food Safety Authority (EFSA) recommends an intake of 2.5 litres of water for men and 2.0 litres of water for women per day, via food and drink consumption.(500) Of this, they suggest that 70-80% of the daily water intake should come from drinks, and the remaining 20-30% should come from food.
In the next article on the the topic of energy, we'll take a closer look at how exercise impacts our energy levels and how much sleep we need to ensure we are performing optimally through the day. Thanks for tuning in.
Sports & fitness nutritionist, researcher and author on a mission to improve the human condition. Focusing on evidence-based and outcome-based nutrition, training, mindset & environment