By Drew Maffett | 02/21/2025
An exciting aspect of sports nutrition is understanding how the body processes macronutrients like carbohydrates, proteins, and fats into energy. This knowledge is key to becoming not just a successful athlete but also a healthier person. Strategies like nutrient timing, total energy intake, and dietary supplements can contribute to building muscle mass, managing weight, and achieving your goals around sports nutrition.
What Is Sports Nutrition?
Sports nutrition is the study and practice of optimizing dietary intake to enhance athleticism, recovery, and overall fitness. Sports nutrition differs from general nutrition, because it addresses the unique energy demands of athletes, recognizing that their caloric and nutrient requirements differ significantly from non-athletes. While it is easy for you to be intimidated by the terminology of sports nutrition, it is essential to understand is that all food eventually becomes immediate fuel or is stored as reserve fuel.
Why Is Sports Nutrition Important?
At the core of sports nutrition is a combination of physics, chemistry and biology. Understanding how metabolism works is a foundation for preventing early fatigue, minimizing injury risk, and supporting muscle recovery.
Nutrition and Athletic Performance
Athletes need macronutrients as their primary sources of energy. These macronutrients consist of:
- Carbohydrates
- Proteins
- Fats
Carbohydrates
Carbohydrates are the body’s primary source of energy, especially for distance athletes and aerobic exercise. They provide energy through glycogen breakdown, a process where stored carbohydrates are converted into glucose to power your muscles.
During intense exercise, your body relies on glycogen as a quick source of energy and to sustain your sport performance over time. Without enough carbs, your body struggles to maintain energy output, which leads to early fatigue, diminished endurance, and slower recovery.
- Function: Simple carbs fuel high-intensity and endurance activities by providing an instant burst of glucose. They also support waste elimination and intestinal health. Complex carbs take longer to break down and are used during sustained exercise performance.
- Dietary sources: Found in fruits, vegetables, grains, and legumes
- Calories: Contains four calories per gram
Fats
Fats normally are found in three forms. There are trans fats, saturated fats, and unsaturated fats.
Trans Fats
Trans fats are commonly found in processed snacks, baked goods, some breakfast foods, and fried or battered foods. Ideally, trans fats should be avoided because they increase the risk of chronic diseases.
Saturated Fats
Saturated fats are “saturated” with hydrogen atoms, meaning that each carbon atom in the fat chain has single bonds and is fully surrounded by hydrogen atoms. The orientation of these molecules makes saturated fats more energetically stable. However, saturated fats are also harder for the body to break down, because the body requires more energy to disrupt these tightly packed molecules.
Saturated fats are found in foods such as butter, fatty meats, and ice cream. These foods should be consumed in moderation due to their link to cardiovascular disease.
Unsaturated Fats
Unsaturated fats are the healthier fats that support better heart health and nutrient absorption. They have at least one double bond between carbon atoms.
This double bond creates a “kink” in the atomic structure, preventing fat molecules from packing tightly together and making them less energetically stable molecules.
- Function: Supplies long-term energy, supports hormone regulation, and aids in the absorption of fat-soluble vitamins
- Dietary sources: Found in olive oil, avocados, fatty fish, nuts, and seeds
- Calories: Contains nine calories per gram
Proteins
Proteins, found in most animal products, are critical for muscle synthesis. Muscle synthesis involves the building of new muscle fibers are built and the repair of damaged tissues.
During exercise, muscle fibers experience stress and microscopic tears. Protein helps repair these fibers, supporting muscle growth and recovery.
Amino acids are fragments of larger proteins, which serve as the building blocks of DNA and support countless cellular processes. Protein synthesis not only helps maintain lean body mass but also supports muscle contraction during exercise, which helps athletes perform at their best and recover faster.
High-quality protein is particularly important for athletes who participate in resistance or endurance training. Consuming protein both pre- and post-workout enhances muscle recovery, reduces muscle breakdown, and helps athletes maintain or build muscle.
- Function: Repair muscle tissue, build lean body mass, and support recovery
- Dietary sources: Found in lean meats, fish, eggs, nuts, beans, tofu, soy products, and low-fat dairy products
- Calories: Contains four calories per gram
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Micronutrients for Sports Nutrition
In addition to macronutrients, the body also requires micronutrients. Micronutrients involve:
- Fat-soluble vitamins
- Water-soluble vitamins
Vitamins: The Key to Energy and Recovery
Vitamins that are soluble in fat can be stored in the body’s fat tissue. That way, they are available for longer periods without someone needing to consume them daily.
Water-soluble vitamins must be consumed daily because the body cannot store excess amounts. These vitamins support energy production, immune function, and tissue repair.
Fat-Soluble Vitamins
- Vitamin A: Is essential for vision, immune function, skin health, and supporting cell growth and differentiation
- Vitamin D: Is essential for muscle contraction, immune health, calcium absorption, and bone strength.
- Vitamin E: Serves as a powerful antioxidant, supports immune function, protects cell membranes, and promotes skin and tissue health
- Potassium (Vitamin K): Maintains electrolyte balance, regulates fluid balance and hydration, especially during prolonged or vigorous exercise
Water-Soluble Vitamins
- Vitamin C: Supports the immune system, aids in collagen formation, and enhances recovery by reducing cellular damage caused by the toxic byproducts of metabolism
- Vitamin B Complex: Supports energy production, metabolism, and nerve function, and are especially important for athletes involved in intense or endurance-based sports
Nutritional Needs for Athletes
Ideally, athletes should consume a balanced diet consisting of foods with macronutrients and micronutrients. Calorie needs vary by athlete, and a sport nutritionist can tailor a diet to suit an athlete’s needs and goals.
Macronutrients
Athletes should eat 1.2-1.7 grams of protein per kilogram of body weight daily. An athlete’s diet should derive 50-70% of total calories from carbohydrates to maintain optimal performance.
Micronutrients
Incorporating a diverse range of nutrient-dense foods – including leafy greens, fruits, whole grains, lean proteins, and healthy fats – will help ensure athletes meet their micronutrient needs. In some cases, supplements may be necessary to fill any nutritional gaps.
For female athletes, special attention must be given to their micronutrient intake. Calcium and vitamin D are particularly crucial for maintaining strong bones. The iron levels of female athletes should also be monitored, as insufficient iron can lead to fatigue and hinder athletic performance.
Exercise and Fluid Replacement
When it comes to sports nutrition, water is key. Water is a huge part of our bodies; it is 50% to 70% of our body weight and plays a vital role in thermoregulation and nutrient transport.
Hydration isn’t just about quenching thirst; it’s the foundation of good performance. Dehydration can derail your endurance, impact your cognitive function, and leave you struggling to push through your workout.
To stay ahead of the game, athletes should:
- Drink 500-600 milliliters of water two to three hours before exercise
- Drink 200-300 milliliters of fluid every 10-20 minutes during exercise.
- Restore the body’s balance with fluids and electrolytes, particularly sodium, to jumpstart recovery after exercise.
Proper hydration doesn’t just keep you going. Hydration sustains the heart’s stroke volume, ensuring nutrients are efficiently delivered to your hard-working muscles.
The Science of Electrolyte Balance
Maintaining the delicate balance between water and electrolytes is essential for peak physical performance, especially during intense or endurance activities. This balance involves fine-tuning how your body manages blood pressure and energy levels.
During exercise, your body adjusts its cardiac output (the amount of blood pumped by the heart) and total peripheral resistance (how hard the blood vessels work to move blood). This regulation keeps your mean arterial pressure (MAP) stable, preventing energy dips and muscle fatigue.
The Role of Vasopressin in Maintaining Fluid Balance
Fluid balance is largely governed by vasopressin, also known as the antidiuretic hormone. When your body detects a water deficit, vasopressin is released and the kidneys are signaled to hold onto water instead of excreting it. At the same time, thirst mechanisms kick in to encourage rehydration.
Electrolytes like sodium and potassium are crucial for maintaining this balance, keeping your cells hydrated and your performance steady. Here’s the fascinating part: in the kidneys, water reabsorption works hand-in-hand with salt retention.
Imagine this situation: You’re thirsty but don’t get a drink. Vasopressin is released to help your body conserve water by holding onto it in the kidneys.
But as water is retained, electrolytes like sodium can accumulate, potentially forming crystals in the kidneys. These crystals are more commonly known as kidney stones.
Once you finally hydrate, the concentration gradient in the kidneys shifts. This shift allows water and electrolytes to be properly filtered through the body, restoring balance and preventing further complications.
Hydration is critical in sports nutrition. Proper hydration not only supports fluid balance but also plays a vital role in maintaining hemodynamics, which ensures consistent blood flow and oxygen delivery during physical activity. It impacts everything from energy levels to muscle function and even recovery, making it a cornerstone of optimal performance.
By understanding the science behind hydration and electrolyte balance, you can elevate your performance and recovery and ensuring your body operates at its best. Never underestimate the power of water – it is sports nutrition’s unsung hero.
Timing and Food Consumption
“Nutrient timing” involves strategically consuming nutrients before, during, and after exercise. According to the International Society of Sports Nutrition (ISSN), well-planned nutrient timing can enhance the body’s performance and recovery, supporting short-term energy needs and long-term training adaptations.
Pre-Exercise Nutrition
Two to four hours before exercise, consume a balanced meal rich in carbohydrates (one to four grams per kilogram of body weight), moderate in protein, and low in fat to optimize energy availability. Carbohydrates are essential for glycogen storage, which fuels exercise performance, especially for endurance athletes.
Approximately 30 to 60 minutes before exercise, consume a small, easily digestible snack. A snack with about 30-60 grams of carbohydrates can provide a quick energy boost, especially for intense or prolonged activities.
Nutrition During Exercise
For endurance activities lasting longer than 60 minutes, a small, regular intake of carbohydrates (30-60 grams per hour) is ideal for maintaining steady blood glucose levels and delaying fatigue. This carbohydrate intake can be achieved through consuming sports drinks, energy gels, or fruit.
Post-Exercise Nutrition
Within 30-45 minutes post-exercise, focus on replenishing glycogen stores and initiating muscle repair. The ACSM and ISSN recommend a carbohydrate intake of one to one and a half grams per kilogram of body weight combined with 15-25 grams of a high-quality protein. This combination of a carbohydrate and protein intake enhances glycogen synthesis and muscle protein repair, crucial for recovery and adaptation.
Resistance athletes should consume protein shortly after exercise (within two hours) to maximize muscle protein synthesis. Distribute total protein intake evenly throughout the day (1.4–2 grams per kilogram of body weight daily).
Following these guidelines ensures that your body has the right nutrients at the right time to fuel activity, recover effectively, and adapt to training demands. By aligning your meals and snacks with exercise timing, you can optimize performance, reduce fatigue, and support long-term fitness goals.
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The Science of Metabolism and Energy Production
The human body relies on macronutrients for energy and essential cellular functions. These nutrients are metabolized differently depending on the body’s state.
There is the “fed” state, when nutrients are stored. The other state is the “fasting” state, when stored energy is oxidized to fuel the body.
Understanding the pathways of macronutrient metabolism provides insight into how the body converts food into usable energy or reserves for future use.
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Carbohydrate Metabolism
Carbohydrates are broken down into small sugar molecules (glucose, the body’s primary energy source). Glucose undergoes glycolysis, a metabolic pathway that produces energy.
In the “fed state,” excess glucose is stored as glycogen in the liver and muscles, or it is converted to fat for long-term storage.
If the body enters a starvation state, glucose derived from glycogen stores becomes scarce. At this point, alternative sources such as glycerol (from fat breakdown) are broken down to glucose, ensuring critical organs like the brain and blood cells have an energy supply to survive. When you are fasting or in the “starvation state,” glycogen is broken down to maintain blood glucose levels and support cellular functions in your body.
Fat Metabolism
When you consume fats, they are digested as fatty acids and glycerol, which serve distinct roles. Fatty acids enter the beta-oxidation pathway to be broken down for energy or stored as triglycerides in adipose (fat) tissue. In the “fed” state, fats are also synthesized into cell membrane components.
During fasting or starvation, fatty acids are used to produce ketone bodies, a crucial alternative fuel for the brain and body when glucose levels are low. This shift helps preserve muscle protein by reducing the need for glucose synthesis from amino acids.
Protein Metabolism
Proteins are broken down into amino acids, which serve a dual purpose. Amino acids can be used to make new proteins for cellular repair and growth, or they can be oxidized for energy.
In the “fed” state, amino acids primarily support the construction of protein molecules. In fasting conditions, excess amino acids are converted to glucose or ketones to meet energy demands.
Unlike carbohydrates and fats, proteins are not stored as a primary energy source. Instead, they are utilized only when energy demands exceed carbohydrate and fat availability, such as during prolonged starvation or extreme physical exertion.
Physical Activity Determines Carbohydrate or Fat Utilization
The body’s utilization of carbohydrates and fats varies with exercise intensity. During low- intensity exercise, fat breakdown provides a steady energy supply.
As exercise intensity increases, the body shifts towards carbohydrate breakdown to make more energy. During endurance activities, fats stored in adipose tissue and muscles are broken down into fatty acids and glycerol, providing a sustained energy supply. This shift is called the “crossover concept," which describes how the body transitions from fat-derived energy to carbohydrate-derived energy as exercise intensity increases.
Understanding metabolic pathways is essential for athletes and nutrition professionals to develop effective training and nutrition strategies. A well-planned diet that is tailored to an individual’s specific needs can enhance performance, support recovery, and minimize injury risk. Sports nutritionists can also provide personalized guidance to optimize an athlete’s nutrient intake based on exercise demands and goals.
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Designing An Athlete’s Diet
Crafting a balanced nutritional plan is essential for athletes to improve performance during an athletic competition, support recovery, and maintain overall health. This graphic shows sample diet plans tailored for improving muscle strength and endurance in athletes.
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Debunking Nutrition Myths
Sports nutrition plays a vital role in enhancing athletic performance, but there is a lot of misleading information out there. To avoid confusion, athletes should rely on reputable sources like the U.S. Olympic and Paralympic Committee (USOPC) and the American College of Sports Medicine (ACSM), which provide science-backed recommendations for proper nutrition.
Additionally, athletes have unique nutritional needs compared to non-athletes. Their diets must be tailored to support increased energy expenditure, faster recovery, and overall performance. Certified sports nutritionists are the best resource for creating a diet plan specific to an athlete’s needs, which is especially useful prior to athletic competition.
Tailoring Diets Based on BMI
Body Mass Index (BMI) is a general indicator and may not accurately reflect an athlete’s health. It's widely known that athletes with an increased ratio of muscle to fat may have a BMI categorized as overweight or obese, despite being in excellent health.
Ideally, any dietary adjustments should consider an individual's goals:
- Weight management: For weight loss, create a calorie deficit through a balanced diet and exercise.
- Muscle gain: Eat more protein (1.4-1.7 grams per kilogram of body weight daily) and participate in resistance training.
- Endurance enhancement: Prioritize carbohydrate-rich diets (6-10 grams per kilogram of body weight daily) to fuel prolonged activities.
The Effectiveness of Sports Supplements
Certain sports supplements have proven benefits for performance and recovery when they are used appropriately:
- Creatine: Enhances energy, strength, and cognitive function
- Whey Protein: Supports muscle repair and growth
- Sodium Bicarbonate: Buffers lactic acid, improving endurance
- Caffeine: Increases focus, delays fatigue, and boosts endurance
It's important to keep in mind that supplements can come with side effects like digestive discomfort, water retention, or dependency. Consult a certified nutritionist or physician to ensure safety and efficacy.
A common dietary supplement that is often overlooked is sports drinks. Sports drinks are an effective tool for maintaining hydration and electrolyte levels during prolonged or high-intensity physical activity and is a great reminder of how water and salt reabsorption operate in synergy.
Drinks like Gatorade® replenish essential electrolytes like sodium and potassium, which attract water into cells and support sustained aerobic exercise. Energy drinks, while offering a caffeine boost, should be consumed carefully due to their sugar content. The sugar in energy drinks can affect energy stability and hydration, as well as increase calorie intake.
Misconceptions in Sports Nutrition
There are various misconceptions in sports nutrition. Here are some of the most common mistakes that athletes make:
- Excessive protein intake: Protein is essential but consuming more than necessary doesn’t translate to greater muscle gains. For a 150-pound athlete, the amount of protein should range from 110-150 grams per day. Exceeding this amount offers little additional benefit and increases the risk of developing kidney issues.
- Energy drinks: Energy drinks often contain high sugar and caffeine levels, which can lead to dehydration and energy crashes. Opt for water or sports drinks for hydration supplementation instead.
- Fasting workouts burn more fat: The idea that exercising on an empty stomach leads to greater fat loss is a persistent myth. While fat oxidation may increase during workouts, the lack of carbohydrates can result in reduced intensity, decreased performance, and potential muscle breakdown. For most athletes, eating before a workout improves overall output and results.
- Eating clean is enough to optimize performance: “Clean eating,” focusing solely on unprocessed foods, is beneficial but may not meet the specific energy and macronutrient demands of athletes. For instance, elite athletes may need a higher carbohydrate intake or fast-digesting foods (like sports drinks or gels) during competition. A rigid “clean eating” mindset can sometimes hinder performance, so it's important to remain intuitive when trying a new diet.
- The carnivore diet enhances an athlete's performance: The carnivore diet, which eliminates plant-based foods and focuses exclusively on meat, is often marketed as a performance-boosting regimen. However, this approach lacks the carbohydrates necessary for glycogen replenishment, an essential energy source during exercise. Athletes following the carnivore diet may experience early fatigue, reduced endurance, and impaired recovery due to the absence of nutrient diversity and dietary fiber.
Sports nutrition is the secret to leveling up your performance and feeling unstoppable, no matter your sport or fitness routine. When you understand how to fuel your body with the right mix of macronutrients, hydration strategies, and nutrient timing, you’re setting yourself up for athletic success, even if sports change in the future. With the right knowledge, you can eliminate trendy diets and outdated myths to make sports nutrition choices that truly work and achieve better physical fitness.
Sports and Health Sciences Degrees at American Public University
For adult learners who are interested in sports nutrition, athletic performance, sports medicine, and other similar topics, American Public University (APU) offers two degrees:
- An online Bachelor of Science in Sports and Health Sciences
- An online Master of Science in Sports and Health Sciences
Courses taught in these programs are taught by expert faculty members and include the foundations of nutrition, sports nutrition, and exercise programming and testing. Other courses include kinesiology, nutrition for sports performance, and advanced exercise and sport physiology.
For more information, visit APU’s nursing and health sciences program page.
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Drew Maffett is a current student at American Military University, seeking a master’s degree in sports and health sciences with a concentration in human performance. She also holds a B.S. in exercise physiology from Ohio University and is a certified emergency medical technician.
As a combat medic veteran, Drew combines advanced exercise physiology topics with clear communication, making complex topics accessible to all readers. Her passion lies in reducing educational barriers and fostering personal growth through impactful content creation to encourage critical thought. Drew also aims to empower diverse audiences with actionable health information, showcasing her ability to simplify intricate biological concepts for broader understanding and application.
