Carbohydrates should be the foundation of any healthy meal plan, especially that of an athlete. An athlete should consume from 6 to 10 g/kg/day of carbohydrate, depending on activity level and type of activity [1]. For someone exercising 1 h/day, the lower end of this range would suffice, but athletes exercising intensely, possibly even more than once a day, should aim for the higher end of the range. Intake of carbohydrates should be spread fairly evenly throughout the day rather than included only in one big meal, for example, at dinner [4].

Carbohydrates are found in different places in the body: stored in the muscles as glycogen, stored in the liver as glycogen, and circulating in the blood as glucose [4]. Athletes need to consume enough carbohydrate so that their glycogen stores are maximized and ready when they begin exercise. The body uses carbohydrates to fuel exercise; half of the energy for moderate-intensity exercise comes from muscle glycogen and blood glucose and two thirds of the energy for high-intensity exercise does [4]. Athletes need to replace these stores during exercise lasting longer than 1 h in duration with food and/or drink that contain carbohydrates in order to have continued fuel. It is important to note that no amount of eating or drinking during exercise can make up for beginning with depleted stores [5].

Adequate carbohydrate intake is not only important for endurance athletes such as runners or cyclists who might generally hear advice about carbo loading. Athletes on team sports or those who compete in shorter distance activities will also need stored energy for practices and will need adequate fuel available for the short bursts of energy necessary during competition. Officially, carbo loading is more than just eating a pasta dinner the night before a race or athletic event, although some athletes may still do this as a last ditch effort to top off glycogen stores. As stated previously, anyone participating in athletics should make sure to get enough carbohydrates in their diet on a consistent basis. The theory behind carbo loading is that athletes can maximize their glycogen stores by eating the low end of the recommended amount of carbohydrate starting 6 days prior to the competition or event. They continue with this for 3 days at which point they increase to the high end of the recommended amount of carbohydrate for the final 3 days leading up to the competition [5].

There are negative consequences associated with inadequate muscle glycogen stores, as well as inadequate liver glycogen stores. When muscle glycogen is too low and not repleted, athletes may “hit the wall” and find that they can no longer continue at the same level of performance as they could previously. This tends to happen more during endurance activities such as a long-distance running event or cross-country ski race. Liver glycogen and blood sugar provide fuel for the brain; when there is not enough an athlete may lose motivation to continue performing or become disoriented despite the availability of the muscle stores to continue—sometimes this is referred to as “bonking” [6]. This is why it is important not only to eat carbohydrates consistently on a daily basis (and possibly also carbo load leading up to an event), but also to eat a source of carbohydrate in the hours immediately prior to the event.

There are many food and beverage sources of carbohydrate from one or more of the following categories: fruit, vegetables, grains, dairy, beans, nuts, and sugar. Some of these carbohydrate sources are healthier than others. Accordingly, the U.S. government’s MyPlate recommendations suggest that half of all grains consumed should be whole grains such as whole wheat, whole wheat pasta, brown rice, quinoa, oats, bulgur, barley, and amaranth in order to help prevent heart disease and ensure adequate fiber intake. In addition, not all carbohydrates perform the same once they have been eaten. The speed and amount which a certain food raises a person’s blood sugar is referred to as the glycemic index (GI). A low GI food will slowly raise blood sugar and slowly bring it back down. A high GI food will spike blood sugar quickly and can bring it down fast as well. The blood sugar response to a particular food depends on the makeup of the food as well as what it is eaten in concert with. Generally speaking, a low GI food such as a banana or glass of milk might better serve an athlete prior to exercise whereas a high glycemic index food like gummy bears or juice might better serve an athlete during or immediately after exercise [6].

The RDA for protein intake for a healthy adult is 0.8 g/kg/day and the “Acceptable Macronutrient Distribution Range” is 10–35 % of daily calories provided by protein. For endurance athletes, that amount can increase to 1.2–1.4 g/kg/day and the amount can go even higher for strength training athletes, up to 1.7 g/kg/day. Some athletes may think that they need to take in excess amounts of protein in order to build muscle. However, it is a combination of total energy intake with sufficient protein and resistance exercise that build muscle, not excessive protein intake. Athletes interested in building muscle must eat appropriate amounts of “protein-sparing” carbohydrate in order for the essential amino acids to remain free to build muscle [1]. There is also the opposite risk of having too little protein which can cause the breakdown of muscle, a side effect any athlete will want to avoid [5].

While it is entirely possible for an athlete to meet her protein requirements by eating a varied diet that includes protein sources such as meat, fish, poultry, tofu, beans, legumes, nuts, and dairy, some turn to protein powders or bars. An athlete can find protein powder in all sorts of varieties: from standard whey or soy protein to egg white and beef protein to vegan pea, hemp, and rice protein (notice that all of these protein powders originate from food sources). If she finds it convenient and cost effective to consume protein in powder form, it is not necessarily detrimental (although a thorough review of other ingredients is important) but it is not necessary either. Regardless of the source or form, protein still contains 4 cal/g. An athlete should be aware of not just the grams of protein she is consuming, but also the potential for extra calories in an extremely high-protein diet. Also, many protein powders are flavored with artificial sweeteners in order to reduce the calories in the powder but keep the taste acceptable. Athletes who might be sensitive to artificial sweeteners, such as those with irritable bowel syndrome, should be sure to read label and ingredient list on protein powders carefully.

When a person consumes excessive amounts of protein, she risks becoming dehydrated due to the increased urine that is created as the body disposes of the excess ammonia derived from amino acids. This is called nitrogenous waste and is created by the liver once the kidney has worked to filter out the excess nitrogen [5].

The percentage of fat in an athlete’s daily diet should be between 20 and 35 %. Less than this amount may have an adverse affect on performance and can hinder a person’s ability to absorb fat-soluble vitamins (A, D, E, and K). Eating a diet higher in fat than 35 %, however, does not appear to be beneficial to athletes [1, 4]. Athletes who need to consume large amounts of calories each day to avoid an energy deficit should utilize fat source not just for its health benefits but also due to its energy density. Fat contains 9 cal/g as opposed to carbohydrates and protein both of which contain 4 cal/g. However, emphasis should be placed on unsaturated fats which are derived from plant sources such as avocado and nuts rather than saturated fats which are derived from animal sources such as butter and cream.

For low-intensity exercise (and when a body is at rest), fat stored in the body is used as a source of fuel. As exercise intensity increases, the body more efficiently uses carbohydrate more so than fat as the fuel source [5]. Some athletes may ask about using medium chain triglycerides (MCTs) as an alternative energy source to carbohydrates. MCT oil is marketed to athletes as a way to boost energy and maximize performance, although research studies have found little benefit related to its use. Instead, MCT has actually been shown to cause gastrointestinal distress and elevated blood lipid levels [4]. Another type of fat advertised to athletes is branch-chain amino acids (BCAAs) made up of leucine, isoleucine, and valine. These have also shown no improvement in performance, though they may have a benefit related to immune function [4].

Athletes will perform better if they are adequately fueled prior to performance [1]. What a person eats prior to practice or competition will depend partly on how much time is available. Having a meal 3–4 h prior to activity and a small snack 1 h before can give the body time to digest but remain fueled, which is realistic for activities that occur later on in the day. If an athlete will be practicing or competing in the early morning, she may not have enough time to eat anything substantial between waking up and exercising. In this case, a small meal prior to bed the night before might be the best way to ensure that her body is ready for activity upon waking [6]. Ideally, she will wake up at least an hour before activity so that she can eat a small meal and digest before beginning exercise.

While many have sought the “perfect” pre-race meal, it will likely differ from individual to individual based on foods that they best tolerate. The meal or snack should be consumed with enough time to digest it, should leave the athlete feeling satiated, should be low in fat and fiber so as not to cause an upset stomach, should be high in carbohydrate to give energy, and should be moderate in protein [1]. This combination may sound overly specific and possibly even unattainable, but there are easy ways to achieve this. For example, a piece of white bread with a small amount of peanut butter or an English muffin with a slice of cheese and an egg white would meet these requirements, as would some trail mix and a glass of orange juice. The pre-race or pre-workout meal does not need to come in a package and does not need to be sold for that specific purpose; often the normal foods that one eats, perhaps with slight modifications to portion size and makeup, can be just the right pre-workout meal or snack.

Here are some other suggestions for healthy pre-race meals or snacks (portions depend on timing and intensity of workout, and on the individual athlete):

Consuming carbohydrates during exercise, mainly in the form of glucose, can enhance performance when exercise will last longer than 60 min [1]. It is important that whatever is ingested during activity has been tested by the athlete prior to competition and is known to be well tolerated. Popular products such as gels and chews can provide the necessary fuel and will be quickly digested and absorbed by the body. If exercise will last longer than 60 min, ingesting carbohydrates at the rate of 0.7 g/kg body weight per hour can extend performance [1]. For a 130-lb athlete, this would equal around 41 g of carbohydrate per hour or the equivalent of two energy gels. A small banana and 12 oz of Gatorade would also provide enough carbohydrates for that athlete.

After exercise, it is necessary to restore depleted glycogen stores with carbohydrates as well as rebuild broken-down muscle with protein. There have been a few different reported “ideal” ratios of carbohydrates to protein for post-workout such as 3–1 or 4–1. These ratios may surprise athletes who think that they need to focus primarily on protein for recovery [6]. Chocolate milk is a favorite recovery beverage among many endurance athletes due to the combination of carbohydrate and protein, not to mention the electrolytes that are found naturally in milk such as sodium and potassium [6]. Despite the fact that this simple beverage or other whole foods can provide all of the carbohydrates and protein necessary for a post-workout snack, many athletes believe that they need to consume excess amounts of protein and are prone to believe marketing campaigns and internet postings leading them to recovery shakes, protein powders, and other products that may contain unnecessary nutrients, untested supplements, and chemicals that could harm the body in the long run.