Factors affecting your Energy Balance
What is Energy Balance?
Energy Balance is the relationship between the energy you absorb from the food you eat and the energy you burn.
In simple terms, it’s the difference between “Energy In” and “Energy Out”.
When we are in a positive energy balance, we will gain weight. This means there is a surplus of energy and your body will store this surplus as either fat, muscle or other tissues.
When we are in negative energy balance, we will lose weight. This means we have a an energy deficit, and the body will draw on its existing tissues such as fat, organs and other tissues to convert them into useable forms of energy.
There are many factors that go into both the “energy in” and “energy out” sides of the equation, which we’ll discuss below.
One half of the energy balance equation relates to Energy In.
More accurately, this figure is represented by the amount of energy absorbed by the digestive system.
The energy we extract from food is broken down into the 3 Macro Nutrients we hear so much about: Protein, Fats and Carbohydrates.
NB. The 4th Macronutrient is Alcohol but this article doesn’t specifically relate to alcohol metabolism.
Each of these macronutrients provides potential energy for our body, which uses several metabolic processes to convert this potential energy into work, heat or to store for future energy requirements.
When energy intake is sufficient, our body thrives.
When we restrict intake too much, certain things start to happen to maintain a neutral energy balance.
For example, our body will up-regulate hormones that drive hunger when we reduce our energy intake. While this response is different from person to person it can, for example, drive us to crave more food so that we increase our energy intake.
Your body will also down-regulate other metabolic processes when you restrict intake, meaning your drive to exercise may decrease.
After understanding that our bodies absorb Macronutrients and convert them to useable forms of energy, the next factor we need to consider when managing your energy intake is knowing the amount of calories in the food we eat.
When you look at most packaged foods, you will find a nutritional breakdown, which generally includes things like Total Energy, Protein, Fats, Carbs, Fibre and some other micronutrients.
The Energy in food is measured in either Kilojoules (kj) or Kilocalories (Cal or kcal).
When we refer to a number of calories in food, we are actually referring to kcal.
While these food labels and food databases (such as My Fitness Pal or similar) are a great guide to the energy breakdown of food, they can be out by as much as 25% either way.
This isn’t because of some sinister plot to sabotage your diet. They are based on averages taken at a particular time and of course, the ingredients may vary. For example, the nutrients in a piece of fruit may vary due to the region it was grown in, the soil, the time of year, how ripe it was when it was picked and more.
When we eat, a multitude of processes occur in our bodies to allow us to extract the nutrients we need to survive from our food. Our body is a very efficient engine and extracts a large portion of the nutrients from the food we eat, but still, not all of it manages to cross the digestive barrier into our bodies.
Variations in total absorption rates of up to 25% can occur from person to person due to genetics, total calorie consumption, choice of foods and health status. Aside from getting into a lab and testing what goes in vs what comes out, it’s difficult to determine your absorption rates..
Absorption rates have been shown to be higher in people who have participated in extreme dieting/calorie restriction suggesting that the body can improve it’s efficiency during times of hardship.
The amount of energy you use in a day, also known as your Total Daily Energy Expenditure (TDEE) is made up of multiple components. These components are:
Base Metabolic Rate (BMR)
Physical Activity (PA)
Non-Exercise Activity (NEA)
Thermic Effect of Food (TEF)
Each of these components varies from day to day based on activity levels, health and hormonal status and your energy intake.
Base Metabolic Rate
Your body spends the majority of it’s energy (approximately 60-70%) keeping you alive by performing a multitude of chemical reactions, from facilitating the transport of nutrients, through to building new cells, hormones and neurotransmitters. It is these functions that make up your Base Metabolic Rate.
As energy is never really gained or lost (it is transferred between entities) we are using the potential energy from the nutrients we eat:
To perform work;
To convert and store the nutrients we don’t use; or
The energy is “lost” as heat.
The amount of work required to keep you alive is influenced by your size, gender, body composition, age, genetics, health and hormonal status. Your body will up-regulate or down-regulate it’s metabolic processes based on all of these factors. For example, as you get smaller your BMR drops. This means your energy output drops as you lose weight.
(NB. This refers to losing weight, regardless of whether it is muscle, fat or anything else.)
Your metabolic rate increases post exercise, particularly after strength training, as your body repairs the damage caused by micro-tears to the muscles. As you build lean muscle, your body will get bigger and your metabolic rate will increase.
NB. Your metabolic rate also increases as you put on body fat, not just muscle, as stored fat is still metabolically active.
Seeing as your body will adjust it’s metabolic rate based on several factors, it is important you adjust your energy intake and choice of exercise to suit your goals. After all, these things will influence your metabolic rate and therefore the outcomes.
When we exercise, our body uses energy. This energy comes from the nutrients we have stored, converted from it’s various sources to be used to regenerate the body’s useable energy currency: ATP.
It makes sense then, that the more active we are, the more energy we use. This holds true to a point, but as we begin to lose energy stores from our tissues, the body will adjust it’s metabolic rate to compensate. If we create an energy deficit that is too great (regardless of whether this deficit is caused by diet alone or combined with increased energy output), non-vital functions begin to slow. Our hormonal status changes and functions such as sex drive, immune function and even your motivation to exercise will drop.
Our choice of physical activity can influence our energy output, in 2 ways. It can simply burn calories as a direct result of the work we have performed, or it can stimulate the growth of lean muscle and increase our resting metabolic rate.
Steady-state long duration cardio exercise such as walking, running, cycling etc is great for burning calories and is definitely suitable for anyone looking to increase their calorie output. However, this type of exercise doesn’t provide much stimulus for muscle growth. We see a lot of people who only do this type of exercise and they often have very low muscle mass and therefore, lower metabolic rates.
Strength training however, may not burn the same number of calories per hour of exercise, but it has the desired effect of stimulating new tissue growth, improving insulin sensitivity and a multitude of other benefits that improve your health and hormonal status.
High-Intensity Interval Training combines the best of both worlds, but it is also very demanding on the body. Recovery time is greater and people who already have very stressful lifestyle factors such as lack of regular sleep and hormonal issues need to be very cautious with HIIT.
Non-Exercise Activity (NEA) includes everything from shivering, coughing and sneezing, to getting out of your chair, to scratching yourself and choosing to take the stairs.
We group these things together as they make up a small, yet still significant portion of your energy output. If you have an active job or are constantly moving throughout the day, your energy expenditure from NEA will be far greater than that of someone who is sedentary. Office workers, drivers, pilots and the typical business owner lead fairly sedentary lives, when you compare them to a builder or a trainer.
One thing to take into consideration with this factor however, is that these activities are generally lower intensity “incidental” exercise, which don’t really provide the stimulus to build lean muscle. Therefore, they are great for extra calorie burning, but not for boosting your BMR like strength training.
Thermic Effect of Food
The heat released or "energy expenditure” over and above our Base Metabolic Rate, caused by digesting food, is known as the Thermic Effect of Food (TEF) or Thermogenesis. It accounts for approximately 10% of your daily energy expenditure, but this figure varies depending on your activity levels and the types of food you eat, along with how much you eat.
Protein has the largest thermic effect. This is one of the (many) reasons we encourage an adequate protein intake when it comes to maintaining a healthy body composition: it literally costs your body energy to digest, improving your energy output.
Carbohydrates come next, but there is a huge difference between processed carbs and raw vegetables. The energy required to break down and digest broccoli for example, is going to be far greater than consuming plain white bread (gram for gram), due to the fact that most of the “processing” has already occurred in the bread.
Fats have the lowest thermic effect as they are generally the easiest to digest.
At the end of the day, the energy expenditure from TEF is not that huge, so it isn’t going to have a dramatic affect on your body composition. Ensuring you aren’t over-eating is still the most important factor when it comes to food intake. However, if you have a diet rich in processed and starchy carbs, high in fats and low in protein, your TEF will be lower than that of someone who eats a diet with adequate protein, rich in unprocessed vegetables, small amounts of starchy carbs, some nuts and seeds and adequate amounts of healthy fats, making the latter the choice for people concerned with weight management and health.
As you can see, there are many factors that go into managing energy balance and when it comes to starting your journey, it’s all about getting the basics right.
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