Macronutrients & THe Energy Pathways
Our bodies require energy to move, breathe, speak and even sleep! This energy is sourced from the food we eat. Whilst food takes on many forms from bread, to tofu, to chocolate and fruits, the three core components remain the same – Protein, Fats and Carbohydrates (the macronutrients).
Each of these macronutrients has a different role in the energy production processes known as our energy pathways. Understanding the role of each macronutrient in these pathways can help to understand the importance of type, timing and amount, and the effect on energy levels, stores and overall outcome.
Protein, Fat and Carbohydrates metabolism are symbiotic and are continuously working together to maintain homeostasis. Our bodies’ cells are constantly changing between different energy systems depending on availability, need and hormonal signalling.
Energy⚡ – What is it?
We may like to think that the food we eat goes into our bodies and straight to our muscles to help us survive, move around and do all the things we love to do. However, the body is an impressively complex system which allows us to generate energy (ATP) from our foods, store this energy and use it in different ways, allowing us to do everything we can do as humans.
The three pathways are specific metabolic pathways (chains of chemical reactions) which result in the release, transfer or storage of cellular energy.
The energy pathways
1. Phosphagen System (ATP-PC)
What is it?
- The fastest energy system
- Rapid conversion of phosphocreatine (PC) to ATP
- No oxygen required
What it does:
- Provides instant energy, it’s the first response energy supplier
- Takes the phosphate from PC and converts to ATP
- Provides energy for quick, short burst movements like jumping, sprint starts, and heavy weightlifts
How nutrition affects it:
Relies on the amount of stored ATP. Whilst we cannot consume ATP directly, we can influence our bodies’ availability of PC.
- Creatine monohydrate consumption can increase PC stores
- Ensuring protein intake is met, creatine can be made from some amino acids
- Carbohydrates – insulin supports creatine transport to muscle
- Micronutrients such as magnesium and B vitamins support ATP regeneration
Performance tips:
- Consume high-quality protein sources
- Ensure you have carbohydrate intake around training (before and after)
- Research use of creatine supplementation (tips for this later!)
2. Glycolytic System (Anaerobic Glycolysis)
What is it?
- Fast energy without oxygen
- Energy source for high intensity but short term: 10 seconds – 2 minutes
What is does:
- Breakdown of glucose/glycogen into ATP
- Result of it is lactate
- Provides energy for activity such as high intensity intervals, 400-800m running
How nutrition affects it:
Carbohydrates directly affect this system – need to sustain good carbohydrate levels to sustain this energy system
- Amount matters – to keep glucose available
- Timing matters – eating carbs before exercise for availability and after exercise carb intake helps restore used up glycogen
Performance tips:
- Hydration: maintain good hydration and electrolyte balance to reduce fatigue and increase glycolytic efficiency
3. Oxidative system (aerobic)
What is it?
- Fat, carbohydrate and protein metabolism for energy production
- Slower production, but is the long-term energy supply
- Requires oxygen
What it does:
- Requires presence of oxygen
- Long term energy supply for low intensity exercise, primary system at rest
- Clears the lactate producted in anaerobic system
How nutrition affects it:
- Carbohydrates – need to maintain intake of this nutrient to ensure glycogen stores are maintained and glucose availability
- Protein – maintain consumption for energy systems to prevent muscle breakdown during endurance sessions
- The body requires a certain amount of fat intake per day; it is one of our macronutrients for a reason! The body stores fat for a range of reasons – protection for our vital organs and for this energy pathway. When we run out of our sparing glucose and glycogen stores, fat comes to the rescue during low intensity work!
Macronutrient Intake
Our macronutrient intake is important, depending on our health, exercise and lifestyle goals. The balance of macronutrient intake can affect our feelings of fatigue, muscle growth and repair as well as our micronutrient absorption and hormone signalling.
All very important things, but ultimately, for general day to day life, eating a healthy balanced diet will ensure that our bodies are getting the fuel they need to support all our intricate systems to work at their optimum.
If you experience health conditions, take medication or have symptoms you are concerned about, please consult a medical professional. These circumstances can lead to a need to follow a particular dietary intake to support your needs outside of the general recommendations.
For exercise, depending on your chosen activity, you can help support your performance and recovery using what we know about our energy systems.
Learn more about the individual macronutrients in our blogs on fats, proteins and carbohydrates.
Endurance Sports
It now makes sense as to why there are so many carbohydrate gels/powders/supplements that are recommended during endurance of sport. These are there to support our glucose availability and try to prevent depletion of the glycogen stores to ensure performance is maintained and can continue to produce the energy required to get over the finish line!
Explosive sports
Creatine supplements are now everywhere! This could help support the explosive power you are able to create, as we understand the phosphagen system requires PC for the creation of ATP using the phosphagen molecule. Make sure you are careful with supplementation – read the doseage and methods carefully, purchase from reputable sources and you can even look up the supplement on informed sport to ensure limit the chance of consuming contaiminated products (espeically if elite athlete!).
Creatine will soon be arriving in our UK dietary supplements database, so if you or your clients are supplementing with creatine, this can now be analysed as part of your nutritional intake in our platforms.
High intensity Sport
Cycling intervals? Middle distance runner? Ensuring carbohydrate volume and timing of consumption are really important before these sessions/competitions.
myfood24
myfood24 healthcare platform now has an energy expenditure calculator alongside the macronutrient calculator to help support healthcare professionals in ensuring macronutrient needs are being met.
The energy expenditure calculator is underpinned by a range of validated equations. Alongside the use of the Physical Activity Level (PAL) multiplier, this provides an estimated energy expenditure in kilocalories.
This data can then be used to calculate macronutrients by entering a gram per kilogram of body weight value for each macronutrient. The system automatically calculates the grams and kilocalorie contribution of each macronutrient.
The automatic calculations and the ability to add the results directly into the patient’s targets creates a seamless and efficient way of tailoring macronutrient requirements to patients for bespoke targets and reporting.
Find the energy expenditure and macronutrient calculators in your patient view under the ‘Diet & Targets’ tab.
Author: Lucy Clarkson, SENr Nutritionist
Editor: Jessica Eardley-Thompson, ANutr Nutritionist & Grace Williams, Head of Nutrition and Operations