Dietary carbohydrates seem to be the most vilified of all macronutrients with some fitness professionals spawning the belief that carbohydrates are the root of all evil and are responsible for a range of health issues such as diabetes, heart disease and cancer. This idea has sparked a low carbohydrate craze that has resulted in best- selling books and supplements only adding to the myth. Certain fitness professionals, bodybuilders, fitness models and athletes still believe that keeping carbohydrate consumption to a minimum is the key to staying lean, improved performance and health. Unfortunately for these individuals losing body fat and staying lean is far more complicated than keeping carbohydrate intake low. In fact, low carbohydrate consumption may actually hinder your performance and inhibit your ability to build muscle and strength. What I plan to do in this article is explain why carbohydrate should be an integral part of your diet when attempting burn fat, build muscle, gain strength and improve performance.
Building muscle and carbohydrate intake
Dietary carbohydrates you consume are stored as glycogen in your muscles and liver. Glycogen is the primary and most efficient energy source used by your muscles during strenuous exercise such as resistance training. When glycogen stores are low, your body is forced to convert amino acids into glucose in order to meet energy demands. Unfortunately, this process is very inefficient and fails to provide our body with adequate fuel for intense training and a high level of performance. To add to these issues, training in a glycogen depleted state can have a catabolic effect on muscle tissue due to lowered glycogen levels impairing protein synthesis and reducing the prevalence of genes needed for muscle growth.1 Therefore, for muscle building purposes having a healthy amount of carbohydrate in your diet is essential.
What if I want to get leaner?
It’s not uncommon for those who are seeking to burn body fat to take a low carbohydrate approach to their diet. However, if one cuts carbohydrate intake too much poor physical performance, irritability and brain fog will all ensue. Not only do our muscles need carbohydrates to perform at a high level, our brain also requires carbohydrates to function optimally. It’s estimated that your brain needs approximately 100 to 130 grams of glucose per day. It should be noted that when carbohydrates are restricted your body can more readily use fat for fuel but as we discovered earlier, carbohydrates are the limiting factor in exercise performance and if you restrict them you too much you will ultimately hit a wall. Perhaps most importantly, fat loss is not determined by simply cutting out one macronutrient but rather by creating a calorie deficit by burning more energy than you consume. Tom Venuto’s book ‘Burn the fat, feed the muscle’ is perhaps my favourite book on eating and training for fat loss and I strongly urge you to buy a copy if you want to gain a more in depth understanding of as he puts it, ‘the fat loss equation’. Venuto recommends that in order to successfully get lean, maintain performance and muscle mass approximately 50% of one’s daily calorie intake should come from carbohydrates.2 Of course this is not a rigid prescription but rather a guide and can be modified based on factors such as genetics and physical activity levels. This demonstrates that one doesn’t have to cut out carbohydrates to any great degree to lose body fat provided caloric intake is controlled. Anecdotally, I myself successfully got down to single digit body fat by keeping my carbohydrate intake no lower than 40% of my total calories.
Implications for athletes
As you might have guessed by now, carbohydrate intake is equally as important for athletic performance. It’s not uncommon for elite athletes to ‘carbohydrate load’ a few days before competition to significantly raise glycogen above resting levels and enhance performance. Carbohydrate loading and high carbohydrate diets have been shown to improve intermittent sprint performance and increase time to exhaustion. 3,4
Furthermore, low carbohydrate diets have been shown to reduce endurance performance, decreased muscle mass, decrease metabolic rate and vigour resulting in a reduced ability to burn fat. Therefore, the use of extremely low carbohydrate or ‘ketogenic’ diets are not recommended.5
So why the confusion?
I believe the myth that low carbohydrate diets are better for weight loss stem from the apparent short term effects associated with taking a low carb approach. A low carb diet results in quicker weight loss initially, however long term changes in bodyweight are comparable to a diet lower in fat and higher in carbohydrates rendering a low carb approach practically pointless if one is seeking a sustained change in bodyweight.
So what causes the short term decline in weight? The majority of weight loss in the early phases of a low carb diet come from glycogen and water loss. This is due to carbohydrate restriction having a diuretic effect on the body. More specifically, for approximately 1 gram of carbohydrate stored in your body’s muscles an additional 3 grams of water is also stored along with it. A low carbohydrate diet is often used by bodybuilders in the final weeks before a contest in order to decrease water retention which gives them a more defined look to their muscles due to reduced bloating and puffiness. However, these results shouldn’t be confused with actual changes in body composition (Fat loss and muscle growth).
Carbohydrate intake recommendations
I’m sure by now you’re probably thinking, ‘well that’s all well and good, but how much carbohydrate should I consume each day?’. If you are metabolically healthy and your goal is to build muscle, improve body composition and performance, a good rule of thumb is to consume approximately 2-3 grams of carbohydrate per pound of body weight per day. That means in you weigh 170lbs (77kg) then your goal should be to consume between 340 and 510 grams of carbohydrate per day. More specific recommendations for those looking to maximise muscle mass are to consume greater or equal to 3 grams per kilogram of bodyweight per day.7
In addition, I would recommend consuming mostly nutrient dense carbohydrate sources. Nutrient dense sources supply your body with essential nutrients to assist metabolic functions, are insulin friendly, high in fibre and assist the burning of body fat. This is extremely important to remember as carbohydrates that are not nutrient dense have the potential to spike blood sugar levels which can aggravate insulin resistance. When a large amount of insulin is spiked on a regular basis our ability to store glucose is impaired resulting in a greater inclination to store fat. To keep things as simple as possible just remember the most nutrient dense sources of carbohydrates are fruits, vegetables and whole grains (such as brown rice, multigrain bread and whole grain pasta).
It should be noted that the above recommendations should only be used as a guide and a starting point. As is the case for most things nutritionally related, one must experiment with different amounts to see works best. For example, those who are extremely active then a slightly higher carbohydrate intake will be required. On the other hand, those who have a decreased ability to store carbohydrate in their muscles (known as being ‘insulin insensitive’) should consume a lower amount of carbohydrate every day to avoid excess gains in fat. Maybe as little as 1 gram per pound of bodyweight.
Hopefully the information in this article will put to rest some of the fears that you may have about consuming dietary carbohydrate. You simply won’t maximise your results and performance without including a healthy amount of carbohydrate in your diet and they should be an integral part of your nutritional regime no matter whether your goal is to burn fat, build muscle, improve performance or health.