Updated: Aug 25
Reaching your full potential as an athlete takes serious work. It takes consistency. It takes sacrifice. It takes countless hours of strenuous, uncomfortable, exhaustive training. As a former collegiate athlete and Ironman triathlete, I know first-hand the physical and psychological demands of performing at a high level, and it’s not easy.
Whether you are a recreational athlete interested in completing your first 5K run or an Olympian going for gold, we all understand that your results are largely dependent on the physical work you put in day in and day out. Is it just about the training though? While your training frequency, duration, and intensity all factor into your end results, your ability to achieve optimal performance largely relies on another key factor: nutrition. In order to maximize the benefits from all those hours in the gym, on the track, on the pavement, on the court, on the trail, in the pool, or on the field — you need to fuel yourself properly. Nutrition provides your muscles and brain with the necessary fuel to perform a their best; and allows your body to sustain energy and recover efficiently. There is no denying that what you put in your body (or don’t put) can have a direct effect on not only your exercise performance, but overall health.
With the overwhelming amount of nutrition information out there, I (as much as anyone) understand the need for a reliable all-in-one guide for sports nutrition — And that is exactly what you will find here. I will translate the science of nutrition to help you understand what, when, and how to properly fuel yourself by providing up-to-date evidence-based recommendations for peak performance. Major topics we will cover include: Energy metabolism, nutrient timing, hydration considerations, and sports supplements.
What Fuels Exercise?
Before applying sports nutrition recommendations, it’s helpful to have a fundamental understanding of what actually fuels our bodies to move. There are three macronutrients that are capable of providing us with usable energy, which include: carbohydrates, protein, and fat. When digested, these nutrients are broken down into smaller compounds and go through a series of metabolic pathways to eventually yield ATP, the readily-available form of energy (4). Anything with calories is made up of macronutrients, which is why we use the words “calories” and “energy” interchangeably.
Athletes need sufficient calories in order perform optimally; and specific macronutrient needs will depend on the intensity and duration of exercise. It’s important to know that as intensity of activity increases, so does your body’s dependence on carbohydrates for fuel (6). At low intensities, your body will primarily use fat for energy — and when it comes to protein; amino acids contribute very little to fuel, unless no carbohydrates are available and it absolutely has to (but this a less-efficient energy-yielding pathway). The big takeaway here is that if you plan to regularly exercise at longer durations and at higher intensities, you need to prioritize consuming enough high-quality carbohydrates on a daily basis.
How much do you need?
In general, carbohydrate intake should make up 50-65% of an athlete’s total calories; and specific daily needs can change based on the duration and intensity of activity. See below to determine the amount of carbs generally required for each type of exercise (13):
LIGHT: Low intensity or skill-based activity: 3-5 grams/kg of body weight/day
MODERATE: Moderate intensity exercise lasting ~1 hour/day: 5-7 grams/kg body weight/day
HIGH: Moderate to high intensity exercise lasting 1-3 hours/day: 6-10 grams/kg of body weight/day
VERY HIGH: Moderate to high intensity exercise lasting 4+ hours/day: 8-12 grams/kg of body weight/day
High-quality sources of carbohydrates: wheat bread, wheat pasta, brown rice, barley, sorghum, quinoa, sweet potato, squash, zucchini, eggplant, most fruits
While protein gets a lot of attention for its role in repairing and rebuilding muscle tissue, it is responsible for performing many other essential functions, including: maintaining water balance, transporting blood, forming antibodies to trigger immune response, maintaining the structure of most organs, and producing just about every hormone and enzyme in our body (4). In the world of sports nutrition, protein intake is important for optimal recovery; however, more is not always better. Making sure to get the right amount at the right time will be beneficial for all athletes.
How much do you need?
In general, protein intake should make up 15-25% of an athlete’s total calories. Similar to carbohydrates, specific protein requirements should be determined by the level of exercise (13):
Sedentary or very low activity: 0.8 – 1.0 grams/kg of body weight/day
Consistent endurance training: 1.2 – 1.4 grams/kg of body weight/day
Consistent weight training: 1.4 – 1.8 grams/kg of body weight/day
Consistent endurance and resistance exercise: 1.6 – 2.0 grams/kg of body weight/day
It is best to divide up your protein intake evenly throughout the day; aim for 20-30 grams of high-quality protein per meal.
High-quality sources of protein: meat, fish, shellfish, poultry, eggs, dairy products, beans, legumes, nuts, seeds, soy products, whey powder
Fatty acids perform several essential functions in the body; such as: helping to absorb vitamins, providing structure to cells, and regulating hormones and inflammation. In short, making sure you have enough high-quality fat in your diet is required for optimal health. For athletes, it’s helpful to know that the breakdown of fat for energy becomes the primary source of fuel during prolonged endurance exercise.
How much do you need?
In general, fat intake should make up 20-30% of an athlete’s total calories. Not all fat is created equal, though! Saturated and unsaturated fat both perform important functions, and you need adequate amounts of both. While it is quite easy to meet your daily requirements for saturated fat, many people do not consume enough of the healthy and essential unsaturated fatty acids, which have powerful anti-inflammatory properties and support brain health and heart health (9). Excellent food sources for fatty acids include: avocados, nuts, seeds, coconut, tahini, nut butter, olives, high-quality cooking oils, and fatty fish (tuna, salmon). Note: individuals who do not consume fish on a regular basis may benefit from supplementation of omega-3 fatty acids at 1.5-2.0 grams/day (9).
What about ketogenic diets for athletes?
It appears that performance during exercise at low- to moderate-intensity can be maintained by individuals who have adapted to high-fat, ketogenic diets (~80% fat, ~15% protein, ~5% carbs). However, at high-intensity exercise, there is insufficient evidence to support that following a ketogenic diet will benefit performance compared to high-carbohydrate diets (8).
Nutrient timing is a term used to describe food and nutrition recommendations for before, during, and after exercise. If you want to truly perform at your full potential as an athlete, you need to pay attention to the timing and composition of your meals.
The primary goals of pre-exercise fueling include:
Maximize glycogen stores
Allow enough time to digest
Train your gut with familiar foods
Achieve optimal hydration status
Strategies for success:
Before any physical activity, it is necessary to have a balanced meal high in complex carbohydrates, moderate in quality protein, and moderate in healthy fat. You should be giving yourself at least 2 hours to digest a full meal prior to intense activity (2). If you know you will be performing in a longer event that will require a high work output (game, race, intense training, etc.); you should also be paying attention to what your dinner looks like the night before! In order to top off your glycogen (storage form of carbohydrates) leading into that event, the meal the night before should also be high in complex carbohydrates (2). Below, you will find examples of pre-exercise meals.
While having a meal 2-3 hours before physical activity is important for proper digestion and absorption, it is common for athletes to experience hunger within 1 hour of activity. In this case, it is completely acceptable to have a small snack beforehand as long as you allow at least 15 minutes to digest to limit GI discomfort during exercise. This snack should primarily consist of easily-digestible carbohydrates and be low in protein, fat, and fiber. Below, you will find examples of snack ideas.
Examples of pre-exercise meals (2-4 hours prior):
Pasta with tomato sauce, shrimp, and roasted vegetables
Baked salmon with sweet potato, broccoli, and a wheat roll
Turkey sandwich on wheat bread with veggie toppings and a side of fresh fruit
Burrito bowl with brown rice, chicken, mixed vegetables, and fresh salsa
Grilled chicken with roasted potatoes and fresh fruit
Oatmeal with walnuts and berries with a side of 2 eggs on toast
Stir-fry with tofu, peppers, and onions over brown rice (light sauce)
Examples of pre-exercise snacks (< 60 min prior):
Whole, fresh fruit
Dates or figs
½ PB&J sandwich
Peanut butter crackers
Toast with jam
Small fruit smoothie
Small bowl oatmeal
Foods to avoid 2 hours prior:
Excessive dairy (milk, yogurt, cheese)
Greasy foods (burgers, fries, pizza)
High-fat foods (creamy dressings, fried foods, excessive oils)
Excessive sweets (cookies, cakes, candy)
Soft drinks, energy drinks, and excessive coffee
Maintain carbohydrate availability
Replace electrolytes lost in sweat
Strategies for success
Glycogen stores in your liver and muscle will deplete after 90 – 120 minutes of high-intensity activity (2). Therefore, if you plan to exercise at a high level lasting longer than 1 hour, you will likely benefit from consuming an easy-to-digest carbohydrate-rich snack or beverage during the event. Perhaps the best option in this scenario is to consume appropriate amounts of a sports drink due to their composition of rapidly-absorbing sugars. Note: Consuming protein and fat during activity is not necessary, unless you are competing in an ultra-endurance event lasting longer than 4 hours (7)
In summary, you only need to worry about consuming anything other than water during exercise if you plan to be working out for longer than 1 hour. The exception would be if you are exercising in extreme heat in which you would benefit from replacing lost electrolytes (sodium and potassium).
So, how much do you need?
Fluid: 16-32 oz./hour (depending on exercise intensity and sweat-rate)
Carbohydrates: 30-60 grams/hour (6)
Sodium: 400-500 mg/hour (depending on sweat composition) (10)
Potassium: 100-200 mg/hour (depending on sweat composition)
Primary goals for post-exercise nutrition:
Replenish: depleted glycogen stores (important for athletes training every day)
Repair: muscle tissues to allow for proper growth and maintenance
Rehydrate: fluid and electrolytes lost in sweat
Strategies for success:
What you choose to eat and drink after physical activity is just as important as what you do before! Many of us have heard of the “window of opportunity” following exercise, but what does that really mean? — and is it valid? It is true that consuming protein stimulates rates of protein synthesis (12) which is essential if you want to maximize the muscular adaptations from training (in other words; improve strength, power, and performance). However, the timing of protein intake may not be as relevant as once thought. Yes, it is still recommended to have high quality protein following exercise, but research confirms that the need for protein immediately (within one hour) is not entirely necessary (1). Current recommendations are to consume 0.4-0.5 grams protein/kg body weight both pre- and post-exercise within 4-6 hours of each other (11). Practically speaking, as long as you have a balanced meal consisting of 20-40 grams of high-quality protein at some point before and after exercise, you will likely be receiving all the potential muscle-building benefits from training.
Keep in mind that it’s not all about protein after exercise! All forms of physical activity, even weight-lifting, can deplete those precious glycogen stores. Considering it can take up to 24 hours to fully replete glycogen (8), athletes should consume adequate carbohydrates following every exercise session so that they are fully fueled leading into their next event. If an athlete plans to perform multiple training sessions in one day, the urgency increases; as carbohydrates should be had as soon as possible post-exercise. When there are less than 8 hours of recovery time in between activity, It is recommended to consume 4 grams/kg of body weight of carbs within 4 hours (8).
Nutrient Timing Summary
Daily consumption of high-quality complex carbohydrates is the best strategy to ensure glycogen stores are topped off.
The night before and 2-3 hours before activity; consume a meal high in carbohydrates and moderate in protein and fat.
Pre-exercise meals should contain 1-4 grams of carbohydrates/kg body weight
Have a light and easy-to-digest snack right before exercise, if hungry.
Consume ~16-20 oz. fluid 2-3 hours prior.
Consume ~8 oz. fluid about 15 minutes prior.
It is important to stay adequately hydrated throughout the day; do not expect to effectively hydrate less than one hour before activity.
If exercise lasts less than one hour; hydrating with plain water is acceptable.
For exercise that lasts longer than one hour; consume 30-60 grams of carbohydrate per hour.
To limit risk for dehydration, avoid more than 2% loss of body weight.
It may be challenging to replace 100% of your sweat losses during exercise; however, it is recommended to aim for replacing ~80% of losses.
Generally, 16-32 oz. of fluid per hour will meet your needs (depends on environment and sweat rate)
Consume 0.4-0.5 grams/kg body weight of high-quality protein within 4 hours.
Spread out post exercise protein intake every couple hours to maximize benefits.
If you are performing two exercise sessions per day, adequate carbohydrate intake in between should be prioritized.
Post-exercise meals should be complete; consisting of high-quality carbs, protein, and fat.
It is recommended to replace fluid losses by 150% to ensure optimal rehydration (Belval et al., 2019). For example, if you lost one pound (16 oz.) during activity, you should consume 24 oz. (16 x 1.5) post-exercise.
Ensuring that you are properly hydrated throughout the day is critical if you want to get the most out of your training and recovery. Optimal hydration status will do all of the following for athletes: (1) Enhance ability to regulate temperature and cool efficiently; (2) Minimize muscle cramps; (3) enhance cognition, decision-making, and concentration; (4) Maximize recovery from training; and (5) Support optimal immune function (3)
Just like proper hydration will support athletic performance, the effects of dehydration will unquestionably impair performance. In fact, the implications of significant dehydration can sometimes take days to fully recover from! (4)
Performance, both physically and cognitively, can be negatively impacted from as little as 2% weight loss from sweat (i.e. 3-4 lbs for 180 lb athlete). Signs and symptoms of dehydration include: lack of concentration, dizziness, early fatigue in training, trouble tolerating heat, delayed recovery, muscle cramps, headaches, nausea and vomiting, and abnormal elevated heart rate (3)
Keep in mind that fluid needs are higher during the following conditions:
Water vs Sports Drinks
The best fluid to consume throughout the day and during meals is water — but there is a time and place for sports drinks. As previously discussed, when exercise increases in duration and intensity, so does your need for carbohydrates and electrolytes. Sports drinks contain sugar and salt in a concentration formulated for optimal digestion and absorption, making them a great option when you are working extra hard and when sweat loss is high. A general rule of thumb is that if your activity lasts longer than 1 hour, it is recommended to consume a sports drink rather than plain water.
Pro tip #1: When hydrating during training — drink fluids that are room-temperature rather than ice cold to promote easy digestion.
Pro tip #2: Take small, frequent sips rather than large gulps or “chugging”.
Simple strategies to achieve adequate fluid intake:
Carry a water bottle bottle wherever you go.
Aim to drink at least 2 cups of water at all meals.
Snack on fruits and vegetables that have a high water content (oranges, berries, melons, pineapple, cucumber, bell pepper, tomatoes, and carrots).
Begin lunch or dinner with a vegetable soup.
Drink a full glass of water as soon as you wake up.
Enjoy herbal tea in the evening.
Can you over-hydrate?
It is possible to consume more fluid than what is lost during exercise, which can cause gastric discomfort. Consequences can become more serious if you drink excessive water during long endurance events without replacing the sodium lost in sweat. In this case, you increase your risk for hyponatremia (dilution of plasma sodium), sometimes referred to as water intoxication. When sodium levels drop too low, you can experience severe fatigue, headaches, muscle weakness, and nausea. Although this is not common, it is seen during ultra-endurance events lasting several hours or during extremely hot and humid conditions (5)
Follow a food-first philosophy! If your diet is balanced and full of variety; and you don’t avoid any major food groups, you are completely capable of achieving optimal health and performance without the need of supplements. However, there are some circumstances in which you may benefit from taking safe and effective supplements form reliable sources.
I can not stress enough how valuable it is to become an informed consumer! Sports supplements in particular are notorious for making false claims, and companies can get away with this due to the lack of regulation. Consider going through the following checklist each time you are tempted to buy a supplement:
Do I need to supplement? Could my physical or mental health benefit?
If you are restricting certain foods, such as whole grains or animal protein, you may benefit from certain supplements.
If you have been diagnosed with a nutrient deficiency, you will absolutely benefit from appropriate supplementation.
If you wish to improve your strength or endurance performance, there are a couple safe and effective supplements worth trying.
Is the supplement safe?
Unfortunately, dietary supplements are not tightly regulated in the United States, as none are FDA-approved. Having said that, there are some reliable third-party organizations who test products for purity. For sports-specific supplements, I highly recommend purchasing products (including protein powder!) which have been “NSF Certified for Sport” or tested by “Informed Choice” (see resources below for website links). This is even more important for athletes who participate under organizations, such as the NCAA, who regularly drug test for banned substances.
NOTE: third-party certifications can not 100% guarantee that a supplement is free from a banned substance; and you are ultimately responsible for what you put in your body!
Is the product free of controversial ingredients, allergens, or additives?
Keep an eye out for certain ingredients that are showing increasing evidence to be harmful from excessive consumption, such as: artificial colorings, artificial sweeteners, carrageenan, hydrogenated fats, hydroxymethylcellulose, or polysorbate.
If you see a “proprietary blend” on the label, just know that there is no way of knowing exactly what ingredients are being used, thus increasing your risk for consuming a banned or harmful substance.
If it sounds too good to be true, it probable is! Look for these “Red Flag” terms:
“Increased Muscle Mass”
“Increased or Decreased Hormone Levels”
“Backed by Science”
“Claims to Treat or Prevent a Disease”
Is the supplement effective? Is there enough evidence to support its claims?
There are only a small handful of legal sports supplements that have been proven to provide a potential performance enhancement. The highly-respected Australian Institute of Sport has synthesized the research to ultimately categorize a comprehensive list of products and ingredients based on their efficacy as an ergogenic aid (see resource link below).
How is the company’s reputation? There are differences in quality!
Not all supplement companies are created equal, and it is always a good idea to look through their website to try and answer the following questions:
Are there clinical trials done on their products?
What affiliations or certifications does the company have? If you see affiliations with NSF, Aegis Shield, BSCG, Informed Choice, USP, GMP, or Consumer Lab; that is a good sign they care about the quality of their product.
Does the company state what they specifically test for? (Heavy metals, pesticides, contaminants, banned substances, etc.)
Recommended supplement companies:
NCAA Banned Substances: https://ncaaorg.s3.amazonaws.com/ssi/substance/2021-22NCAA_BannedSubstances.pdf
Consumer Labs: https://www.consumerlab.com/
NSF Sport: https://www.nsfsport.com/
Informed Choice: https://www.informed-choice.org/
U.S. Anti-Doping Agency (USADA): https://www.usada.org/
World Anti-Doping Agency (WADA): https://www.wada-ama.org/
Australian Institute of Sport: https://www.ais.gov.au/nutrition/supplements
In conclusion; if you are an athlete interested in improving your performance, you must focus on proper nutrition. While many recommendations for promoting overall health and wellbeing overlap with sports nutrition recommendations, there are several nutritional strategies which have been proven to specifically help athletes. When you appropriately fuel and hydrate yourself based on your personal needs, you can unlock your full athletic potential. Consistent and proper training can make you a great athlete; but dialing in your nutrition will make you elite.
Written by: Jack O’Connor, MS, RD Lead Performance Dietitian INC Nutrition LLC
Aragon, A. A., & Schoenfeld, B. J. (2013). Nutrient timing revisited: is there a post-exercise anabolic window?. Journal of the international society of sports nutrition, 10(1), 1-11.
Arent, S. M., Cintineo, H. P., McFadden, B. A., Chandler, A. J., & Arent, M. A. (2020). Nutrient timing: a garage door of opportunity?. Nutrients, 12(7), 1948.
Belval, L. N., Hosokawa, Y., Casa, D. J., Adams, W. M., Armstrong, L. E., Baker, L. B., … & Wingo, J. (2019). Practical hydration solutions for sports. Nutrients, 11(7), 1550.
Benardot, D. (2020). Advanced sports nutrition. Human Kinetics Publishers.
Buck, E., Miles, R., & Schroeder, J. D. (2021). Exercise-Associated Hyponatremia. In StatPearls [Internet]. StatPearls Publishing.
Burke, L. M., Hawley, J. A., Wong, S. H., & Jeukendrup, A. E. (2011). Carbohydrates for training and competition. Journal of sports sciences, 29(sup1), S17-S27.
Costa, R. J., Hoffman, M. D., & Stellingwerff, T. (2019). Considerations for ultra-endurance activities: part 1-nutrition. Research in sports medicine, 27(2), 166-181.
Fritzen, A. M., Lundsgaard, A. M., & Kiens, B. (2019). Dietary fuels in athletic performance. Annual Review of Nutrition, 39, 45-73.
Gammone, M. A., Riccioni, G., Parrinello, G., & D’Orazio, N. (2018). Omega-3 polyunsaturated fatty acids: benefits and endpoints in sport. Nutrients, 11(1), 46.
McCubbin, A. J., & Costa, R. J. (2018). Impact of sodium ingestion during exercise on endurance performance: A systematic review. International Journal of Sports Science, 8(3), 97-107.
Schoenfeld, B. J., & Aragon, A. A. (2018). Is there a postworkout anabolic window of opportunity for nutrient consumption? Clearing up controversies. journal of orthopaedic & sports physical therapy, 48(12), 911-914.
Simmons, E., Fluckey, J. D., & Riechman, S. E. (2016). Cumulative muscle protein synthesis and protein intake requirements. Annual review of nutrition, 36, 17-43.
Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: nutrition and athletic performance. Journal of the Academy of Nutrition and Dietetics, 116(3), 501-528.