What You Should Eat to Fuel your Workouts: Carbs, Fats, Protein

The human body, like any machine, needs high quality fuel in order to function at its very best. For athletes, whose bodies may be the most fine-tuned and remarkable machines on the planet, this requirement is especially critical. Without proper nutrition, an entire season of exercise and training can be entirely wasted, and competitions can be lost or won based on how well you fuel the machine that is your body. All athletes, from amateurs to Olympians, have begun to realize that a proper and well-maintained diet can make the difference between results and waste or victory and defeat.

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Why Nutrition Matters

During athletic training, there are certain needs that must be met in order to turn the body into a high-performance machine; fuel, recovery, and compositional change. All three of these are driven largely if not entirely by proper nutrition. The need for fuel comes in the form of what you eat, as your body transforms the calories in food into energy you can use. The amount of calories necessary is different for every person dependent on inherent body factors and lifestyle, increasing as you become more active and athletic. However more important than how many calories you eat is where you are getting them from.

Carbohydrates, protein, and fat are the three macromolecules that provide these calories, and your body utilizes them in different ways dependent on their chemical composition and energetic breakdown. By properly proportioning the amount of calories and nutrients you get from these sources, you can fine-tune your diet in order to help you achieve your athletic goals.

Carbohydrates, Protein, and Fat


The base of a recreational or professional athlete’s diet should be in carbohydrates. Carbohydrates, which are broken down and stored in your muscles and liver as glycogen, are the limiting factor for proper athletic performance for most athletes, especially those in endurance and power sports like cycling, running, and swimming. Carbohydrates provide almost half of your total energy needs during most bouts of intense training and competition, and produce more oxygen per unit burned than fat, your body’s other primary source of fuel. Carbohydrates should make up the majority of your athletic diet, around 55-65% of your total caloric intake. This provides your body with adequate fuel for moderate-high intensity training, allowing you to achieve maximum performance and prolong hitting “the wall” of fatigue.

By eating carbohydrates early in the day you allow your body to properly fuel itself for the coming workload, and by replenishing them quickly before, during, and after exercise you keep yourself consistently fueled and able to perform at your very best. Slow-digesting carbohydrates such as those with high fiber should be avoided immediately before exercise as they can weigh the stomach down and cause heaviness and nausea.


Many body-builders and lifters tout protein as the most important part of any athletic diet. This is true in some ways, but can often be done in excess in the case of most Western diets. Protein helps largely with the recovery phase of training, repairing the tears and strains that naturally occur in muscles during exercise. For most people, the amount of protein needed is around 10-15% of dietary caloric intake, although that number can be highly variable dependent on the intensity and type of exercise. Strength trained athletes will require more protein in order to help re-build and improve their muscles after high intensity weight-lifting sessions, where as endurance athletes require more moderate amounts.

The total percentage is important, but more so is the quality of the protein, whether it provides the full array of amino-acids, the building blocks of protein. Protein supplements are often used in order to achieve these consumption goals, but can often be over-used which can lead to dietary fluctuations that may hurt rather than help. By varying your sources of protein and making sure you get enough in a natural diet, you can get the most out of your recovery and utilize the protein in the best way possible.


Fat is the first macromolecule to be utilized by the body for energy, as it provides about 9 calories per gram, whereas carbohydrates and protein provide about 4 calories per gram. Fat is the primary fuel source for low-level to moderate exercise such as walking or jogging, and is highly important for longer endurance events that are at lower intensities. However while fat is easily stored in the body and is calorie-dense, it also takes longer to breakdown and digest by the body.

Fat consumption should not fall below 15% of total dietary intake, and for most should range around 20-35%. Those wishing to lose weight should decrease their fat intake, but before should try eating fats through healthier means by switching their sources of essential fatty acids, as in avoiding the unhealthy trans & saturated fats found in butter and many processed foods. Fatty acids such as Omega-3 are found in fish, flaxseed, and walnut oils, are highly beneficial and can aid in joint and tissue recovery after exercise.

The Takeaway

Properly proportioning carbohydrates, protein and fat, and making sure you are getting enough of all of them in order to meet your body’s basic as well as athletic needs, is one of the most important steps you can take in your physical training. By properly fueling your body, allowing it to recover, and giving it the proper nutrients to become it’s very best, you provide the base onto which all your physical training will be built upon. The necessity and importance of it cannot be overstated, and should never be under-estimated. Transform yourself from the outside in, and allow your body to become the athletic machine it was meant to be.


jackie kellerJackie Keller, Founding Director of NutriFit, LLC, is a licensed and certified wellness coach, nutrition educator and Le Cordon Bleu-trained culinary expert. She is also the author of Body After Baby The Simple 30-Day Plan to Lose Your Baby Weight Fast (Avery/Penguin Group; May 2007), and Cooking, Eating & Living Well, a cookbook and guide to nutrition-related lifestyle change.

Featured photo by *clairity*