Understanding your energy systems in the fight against lifestyle diseases

It has never been so easy to consume calorie dense foods. With fast food, mobile app delivery systems, and delicious food blogs online, the temptation to consume the sugary goodness has caused an increase in lifestyle diseases around the world. Obesity, fatty liver disease, type II diabetes are on the rise due to consuming more calories than we expend. These conditions are reversible through creating pathways towards a caloric deficit.

A caloric deficit put more simply is creating a decrease in the number of calories we eat that the body can use to convert into usable energy. Decreasing the number of usable calories means the body must begin converting energy that has already been stored. This could be in the form of carbohydrates (glycogen), fats (lipids) or protein (muscle). Creating a caloric deficit is the most effective way of reducing weight and can be done through both diet and exercise.

The duration of exercise and intensity will determine which energy source will be the most suitable to sustain the desired activity level.
Within the first few seconds of muscular contraction, adenosine triphosphate phosphocreatine (ATP +PC) which is stored in the myosin of the sarcomere (muscle complex) is used very quickly. When phosphocreatine is broken away from adenosine triphosphate (ATP), energy is released, and ATP is created as a by-product. This energy source is useful for movements such as a quick take-off in a sprint to a bicep curl. Once this source becomes depleted, the body then looks for its next supply which is in the form of glycogen. Glycogen is the glucose stored in the body. This conversion takes slightly longer but allows the body to convert the glycogen into usable ATP through glycolysis. This equation does not require oxygen which means that the fuel source is suitable for anaerobic activity no longer than approximately 90 seconds. Glycolysis is used for movements that require a lot of stopping and starting and is a useful form of energy for explosive bouts in sports like soccer or netball.

From here, lipids become the next source of energy. Lipolysis is the desired conversion of fat into triglycerides which are easier to be metabolised into energy. This conversion of fats into energy can last from minutes to hours depending on how much fat is available before the body begins to use protein. As expected, by utilising fat as a fuel source, you’re likely to experience fat loss. Exercise must continue past the thresholds of each previous energy system before lipolysis can be used. Oxygen is required for this conversion which means the exercise becomes aerobic. Long walks, running and swimming are examples of aerobic activity and are also common exercise prescriptions for fat loss.

With this information about energy systems, how can exercise assist in creating a caloric deficit? If your goal is to reduce body fat, by understanding how to put yourself into your desired state of energy conversion you can decrease the time frame needed to achieve your goal through diet alone. Whilst different exercise forms and duration and are often limited to their energy source, it is important to include cardio (aerobic), resistance training (anaerobic) and mobility to reduce other comorbidities such as sarcopenia, osteoporosis or hypertension.

If you’re living with a lifestyle disease or chronic conditions exercise has been proven to have a positive effect and decrease symptoms.  The team here at Absolute Balance understands how to exercise you appropriately to your condition and will help you achieve your goals against lifestyle diseases. Get in contact with us today by calling 9244 5580 or via email at info@absolutebalance.com.au.


Emily Longmuir
BSc. Exercise and Sport Science

Exercise Physiology Student


Berg, J., Tymoczko, J., & Stryer, L. (2019). Fuel Choice During Exercise Is Determined by Intensity and Duration of Activity. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK22417/

P, A. (2019). Human fat cell lipolysis: biochemistry, regulation and clinical role. – PubMed – NCBI. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/16311212