Carbohydrates are broken down into glucose upon digestion and is the primary fuel source used for all of your body’s energy demands, including your
- tissue (muscle), and
- central nervous system (CNS) – brain and spinal cord
Why Carbohydrates Are Important for Exercise, Maintaining/Building Muscle Mass, and Dropping Body Fat
Besides the fact they’re a desirable nutrient to maintain in your diet to make blood glucose balance a much easier task for your body, they are, as mentioned, the primary fuel source for your body, especially for working muscles. Working muscles have multiple fuel sources that they can use, including:
- ATP-CP – the fastest, most powerful, and most limited fuel source available (lasts 10-15 seconds)
- Glucose – the primary fuel source for high intensity, short duration exercise
- Free fatty acids – high energy yielding and long lasting, but slow to break down
- Amino acids – a reserve fuel source used when all other fuel sources are not being metabolised fast enough, or are depleted, to meet energy demands (FYI – this comes from the breakdown of muscle tissue)
Studies have shown that high intensity exercise significantly increases the total amount of body fat dropped compared to low intensity exercise. Any exercise is good exercise, and if you have to perform low intensity exercise to begin with or due to injury or training volume, then by all means perform low intensity exercise. However, high intensity exercise such as HIIT and resistance training is the most economical form of exercise for dropping body fat and preserving muscle mass. The higher the intensity, the better. This is due to the powerful contractions of the muscles during the exercise, and is the reason why dietary carbohydrates are so important for you if you’re looking to get the best results through high intensity training. As your body’s glucose availability diminishes due to a low carb diet, your muscles cannot work as hard due to several physiological factors, but predominately due to the lack of fast releasing energy sources. This consequently lowers the net caloric burn and desirable physiological responses from your workout, which in turn reduces the total amount of body fat you could potentially drop.
Muscle Mass Benefits
I see three tactics people use all the time that jeopardises their long term results:
- To try and drop body fat they cut carbs, get unreal results for a short period of time, and then flat line. So they try to cut them even more, get the worst sugar cravings, have no energy to train hard, start to lose muscle mass, and consequently start to go backwards in progress
- Despite trying to build muscle, they keep their carbs very low as they are afraid of putting on body fat, consequently never building considerable size
- They straight-up actually try to reduce muscle mass, or are afraid of putting a little bit on, as they’re afraid of appearing ‘bulky’ (even though getting ‘toned’ involves building muscle mass) and find it even harder to drop body fat
On the opposite end of the spectrum for the ones trying to build muscle, not only do you need sufficient carbohydrates in your diet to train hard enough to stress and stimulate your muscles in order to create an adaptation (growth), you also need carbohydrates to help accelerate the process of actually building muscle! This occurs in two ways:
- Ingesting sufficient carbohydrates causes a physiological response by which the hormone insulin is released. Insulin helps to clear glucose out of the blood and into cells (particularly muscle and fat), but also helps push other nutrients such as amino acids into the muscle cells. Amino acids are the building blocks of protein and are used by the body to repair and build muscle tissue, thus helping your muscles that you just stressed and stimulated in the gym to grow!
- Muscle size is an accumulation of both myofibrillar and sarcoplasmic growth (click here to read our previous article on this). Consuming sufficient dietary carbohydrates allows your muscles to refuel their glycogen stores, which is sarcoplasmic growth, and adds to the volume of your muscles cells, making them larger.
Potential to Drop Body Fat
Dropping body fat and/or building muscle does come down to how much energy you take in compared to how many calories you burn, however the way in which you achieve that balance is much more complex and can be tweaked for optimisation to make it as easy as possible. There are so many other factors that interplay in achieving your goals, including:
- Macronutrient (protein, carbohydrates and fats) breakdown of your nutritional intake
- Exercise type and intensity
- General activity levels
- Total muscle mass
- Total fat mass
- Insulin sensitivity
- Metabolic rate, just to name a few
How Many Carbs Should I Be Eating?
This is probably the number one question we get asked on a daily basis, and is one of the hardest to answer without knowing a lot more about the person. The short answer is, there is no magic number; everyone is different. But I know that’s going to send you crazy, so here are some factors to help you determine how much you should be having. How many carbs you need depends on:
1. How much muscle mass you have
To start with, remember how your body converts glucose to glycogen to be stored predominately in the liver and muscle cells? Well, everyone for their size can hold roughly the same amount in the liver, however, if you have a lot of muscle mass, you can store more glycogen in the muscle cells than someone who doesn’t have as much, meaning you can consume more carbs. However, once your muscle glycogen ‘tanks’ are full, it then comes down to the next factor.
2. How active you are
Your body at all times will be using a mixture of fuel sources; some will be from glucose (glycogen and circulating blood glucose), some from amino acids (muscle mass and circulating blood amino acids), and some from fatty acids (body fat cells and circulating blood free fatty acids). What ratio of each it uses will depend on your physiological state and your activity at that time, but will never only use one fuel source at a time in healthy individuals. Glucose, the primary fuel source of the body, will continuously be used for energy throughout all activity, whether that’s in a workout, walking your dog, or even brushing your teeth. So the more active you are, the more carbs you need to replenish your glycogen stores. FYI - your brain (CNS) uses considerable glucose to function. Therefore if your brain is very active through work or study, it is utilising glucose as well, and a sufficient carb intake can help boost brain performance!
3. How much fat mass you have
The more body fat you carry, the less carbs you need as your body has more than enough body fat to tap into to fuel metabolic processes without breaking down as much, if any, net muscle mass. However, as you become leaner, your body will start to break down more and more muscle mass for amino acids to fuel your body if glucose availability is too low, therefore meaning you need more carbs in your diet to prevent this from occurring.
One thing to remember when it comes to nutrition and achieving your goals, is that balance is key. Your body was designed to eat all types of nutrients and utilise them for specific purposes. Going extremely low or extremely high in any nutrient, be it carbs, protein, fats, vitamins, or minerals, will never be a long term solution. Your body needs everything in moderation, and will change depending on each person’s circumstances. Lower carb intakes are beneficial in certain situations; however, I can’t stress the word ‘lower’ as opposed to ‘low´ enough. While some people, depending on their goals, body composition and activity levels, may need to go low carb, others, even if their goals are fat loss, may need to only go lower, which may still be quite high! Some people may even need to increase their current carb intake! Everyone is different, and what works for one person, may not work for you; it’s important you adjust your nutritional intake for your body, goals and lifestyle.