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How many calories should I burn during a workout?

 

As with many things…IT DEPENDS.

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Many people believe that the number of calories they burn in a workout directly relates to how much food they can eat in a day. This can turn into a dangerous association very quickly and one relationship you don’t want to be feeding.

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At Foundations, we 100% believe (and tell our clients all the time)…You do not need to earn your food. The amount of calories you can “earn” through exercise makes up very little of the total calories your body will burn during a day.
 

So how else do you burn energy through the day?
 

There are three ways in which your energy expenditure can be separated into:

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Basal Metabolic Rate (BMR)

 

BMR is the rate of energy expenditure (kJ) burned at rest. It includes the energy the body uses to keep all of its systems functioning correctly and accounts for approximately 50-80% of your daily energy use. Essentially, it is the amount of energy your body needs to maintain homeostasis (balance).
 

Your BMR is determined largely on your total lean muscle mass as the leaner you are, the less energy is needed to maintain your body. This is why it is so important to maintain or increase your lean muscle mass when aiming to lose weight.
 

BMR is influenced by a number of different factors working in combination such as age, body size, amount of lean muscle tissue, gender, genetic predisposition, hormonal and nervous controls, environmental factors, age, growth, diet deficiencies, whether you are starving or crash dieting, drug use, illness and physical activity levels.
 

For example, on average;
 

• A male will have a BMR of 7,100kJ and a woman will have one of 5,900kJ.

• Someone with a higher body fat percentage will feel ‘sluggish’ and burn far fewer calories

• Hormonal imbalances can both decrease and increase the calories burnt

• Someone who exercises regularly will often be leaner and therefore burn more calories

• If the temperature is very high or low the body will have to work harder to maintain thermal balance and then burn more calories
   

Although the expenditure is continuous, the rate will vary throughout the day and is usually lowest in the morning.

 

Non Exercise Activity Thermogenesis (NEAT)

 

NEAT is the energy burnt through daily movement and activities including planned physical activity and day to day living. This energy expenditure makes up only 20% or so of the total energy expenditure at rest but with strenuous exercise it may increase 50-fold or more. Again, factors such as weight, age, health and the intensity at which the activity is performed will alter the figure.

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Typically, the approximate amounts of energy (in kJ per kilogram of the body per hour) used are as follows:

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• Sitting quietly- 1.7

• Writing- 1.7

• Relaxed standing- 2.1

• Vacuuming- 11.3

• Running- 29.3

• Swimming (~4km/hour)- 33
   

Obviously, the harder you work, the more calories you burn. During a workout where you increase and decrease your heart rate, you will tend to burn more calories than a workout where you remain at a static heart rate.

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Thermic Effect of Food (TEF)

 

TEF is the energy your body uses to eat, digest and metabolise food and contributes about 5-10% to your total expenditure during the day.
Following the consumption of food, your BMR raises due to the digestion process of the food. It begins as soon as you finish eating and peaks two to three hours later. The rise in your BMR can be anywhere between 2-30%. Different types of food can also alter how much it increases by. For example, fats will only cause a 0-5% increase while carbohydrates and proteins cause 5-10% and 20-30% respectively. Additionally, hot and spicy foods can also have an additional thermogenic effect.

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The Bottom Line

 

If you are focusing on purely the calories you are burning during a workout, you are doing yourself a disservice. There are many other things you could be focusing on than ensuring you get a good metabolic “after burn”. Instead, you should be looking at honing in on your technique, lifting the appropriate weight and avoiding injuries.

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Your workouts should not be a means of just burning calories. They should be something you enjoy and look forward to as well as an integral part of your healthy lifestyle.

 

Although your Fitbits and Garmins can play an important role in determining your calorie expenditure and steps etc, we recommend occasionally training without that sports watch and just focusing on how you are moving. In doing this, you will gain a whole other respect for how your body feels with just pure hard, unguided work!

 

Obviously, the harder you work, the more calories you burn. During a workout where you increase and decrease your heart rate, you will tend to burn more calories than a workout where you remain at a static heart rate.