Fueling your body properly is not about chasing trends or copying elite athletes. It is about understanding how the human body uses energy, nutrients, and fluids to perform work, adapt to training, and recover.
Decades of research in exercise physiology and sports nutrition consistently show that what you eat, when you eat it, and how consistently you fuel yourself directly influence strength, endurance, power output, and long-term progress.
This article breaks down ten science-backed tips to help you fuel your body for better workouts. Every recommendation is grounded in peer-reviewed evidence and explained in a clear, practical way so you can apply it immediately, whether your training focuses on strength, CrossFit, endurance sports, or general fitness.
1. Eat Enough Calories to Support Training
Why Energy Availability Matters
The most basic and most common nutrition error among active people is not eating enough. Training increases daily energy expenditure, and if calorie intake does not rise to meet those demands, the body adapts in ways that negatively affect performance and health.
Researchers describe this concept as energy availability, which refers to the amount of energy left for normal physiological processes after the energy cost of exercise is subtracted. When energy availability is chronically low, the body prioritizes survival over performance and adaptation.
Scientific studies show that low energy availability impairs muscle protein synthesis, slows recovery, disrupts hormone production, and increases the risk of illness and injury. In both men and women, inadequate caloric intake has been linked to reductions in testosterone, estrogen, and thyroid hormones, all of which are essential for strength gains, metabolic health, and recovery.
Athletes and recreational trainees alike experience declines in training quality when calories are too low. Strength decreases, endurance suffers, motivation drops, and perceived effort increases even when training loads stay the same.
Practical Application
If you feel persistently fatigued, struggle to recover between sessions, or notice stalled or declining performance, insufficient calorie intake is often the primary cause. Before manipulating macronutrients or supplements, ensuring that total energy intake matches training demands should always be the first step.
2. Prioritize Carbohydrates for Training Performance
Carbohydrates and Muscle Glycogen
Carbohydrates are the primary fuel source for moderate- to high-intensity exercise. Once consumed, carbohydrates are stored as glycogen in skeletal muscle and the liver. During strength training, interval workouts, and high-intensity functional training, muscle glycogen is heavily relied upon to produce force and sustain effort.
A large body of research shows that low muscle glycogen reduces power output, strength, sprint capacity, and total training volume. Athletes who consume adequate carbohydrates are able to train harder, maintain higher intensities, and complete more total work than those following low-carbohydrate diets.
Carbohydrate availability has also been shown to lower ratings of perceived exertion. In practical terms, this means workouts feel easier and more manageable when glycogen stores are sufficient.
How Much Carbohydrate Is Enough
Research suggests that physically active individuals benefit from carbohydrate intakes ranging from approximately 3 to 7 grams per kilogram of body weight per day. The exact amount depends on training volume, intensity, and frequency. Those training once per day at moderate volumes will require less than athletes performing long sessions or multiple daily workouts.
Whole-food carbohydrate sources such as rice, potatoes, oats, fruit, legumes, and whole grains provide glycogen replenishment along with fiber, vitamins, and minerals that support overall health and recovery.
3. Consume Adequate Protein to Support Muscle Repair and Growth
Protein and Muscle Protein Synthesis
Protein provides amino acids, which are required for muscle repair, remodeling, and growth. Resistance training stimulates muscle protein synthesis, but without sufficient dietary protein, this adaptive response is limited.
Research consistently demonstrates that protein intakes of roughly 1.6 to 2.2 grams per kilogram of body weight per day maximize muscle protein synthesis in active individuals. Consuming protein below this range compromises recovery and reduces the effectiveness of training.
Beyond muscle tissue, protein supports immune function, connective tissue repair, and enzyme production. These roles become increasingly important as training volume and intensity increase.
Protein Distribution Across the Day
Evidence suggests that spreading protein intake evenly across meals is more effective than consuming most daily protein in one sitting. Studies indicate that doses of approximately 20 to 40 grams of high-quality protein per meal stimulate muscle protein synthesis maximally in most people.
Regular protein intake throughout the day helps maintain a positive protein balance and supports consistent recovery between training sessions.
4. Do Not Fear Dietary Fat
Fat and Hormonal Health
Dietary fat is often misunderstood, but it is essential for normal physiological function. Fats are required for the absorption of fat-soluble vitamins and for the synthesis of steroid hormones such as testosterone and estrogen.
Research shows that very low-fat diets can reduce testosterone concentrations in men, which may impair strength development, muscle growth, and recovery. Athletes who consume moderate amounts of dietary fat generally maintain healthier hormonal profiles than those who chronically restrict fat intake.
Fat and Performance
Although fat is not the primary fuel for high-intensity exercise, it contributes significantly to total daily energy intake and supports metabolic health. Adequate fat intake helps athletes maintain energy balance, which is critical for long-term performance and adaptation.
Healthy fat sources include olive oil, avocados, nuts, seeds, eggs, and fatty fish.
5. Time Your Nutrition Around Training
Pre-Workout Fueling
Eating before training improves performance by increasing carbohydrate availability and reducing muscle protein breakdown during exercise. Research shows that consuming carbohydrates before workouts improves endurance, power output, and total training volume.
Including protein in a pre-workout meal further supports muscle protein synthesis and reduces markers of muscle damage. Studies consistently show benefits from eating a meal containing carbohydrates and protein one to three hours before training.
This timing allows for digestion while ensuring nutrients are available when training begins.
Post-Workout Nutrition
Post-exercise nutrition supports glycogen resynthesis and muscle repair. Protein consumption after training stimulates muscle protein synthesis, particularly when combined with carbohydrates.
While the idea of a very short anabolic window has been overstated, evidence supports consuming protein within a few hours after training, especially if another workout is scheduled within the next 24 hours. Consistent post-workout fueling helps maintain training quality over time.
6. Hydrate Properly Before, During, and After Workouts
Dehydration and Performance
Hydration status has a direct impact on physical and cognitive performance. Research shows that fluid losses of as little as 2 percent of body weight can reduce strength, power, endurance, and mental focus.
Dehydration increases cardiovascular strain, elevates perceived exertion, and impairs the body’s ability to regulate temperature during exercise. These effects compound as workout duration and environmental heat increase.
Practical Hydration Strategies
Consistent fluid intake throughout the day is more effective than relying solely on hydration during workouts. Monitoring urine color is a simple and evidence-based method for assessing hydration status, with pale yellow indicating adequate hydration.
During long or high-sweat sessions, replacing electrolytes, particularly sodium, becomes important. Research shows that sodium replacement helps maintain plasma volume and supports sustained exercise performance.
7. Do Not Neglect Micronutrients
The Role of Vitamins and Minerals
Micronutrients play critical roles in energy metabolism, oxygen transport, muscle contraction, and recovery. Deficiencies can impair performance even when calorie and macronutrient intake appear adequate.
Iron is essential for oxygen delivery, and iron deficiency has been associated with reduced endurance and increased fatigue, even in the absence of anemia. Magnesium supports muscle contraction and ATP production, while zinc contributes to immune function and protein synthesis.
Athletes with high training volumes, restrictive diets, or limited food variety are at increased risk of micronutrient deficiencies.
Food First Approach
Scientific consensus supports meeting micronutrient needs through whole foods whenever possible. A diet that includes fruits, vegetables, lean proteins, whole grains, and dairy provides the vitamins and minerals required to support training adaptations and overall health.
8. Fuel Recovery, Not Just Workouts
Recovery Drives Adaptation
Training provides the stimulus for adaptation, but improvements occur during recovery. Nutrition plays a central role by providing energy and nutrients needed for tissue repair and glycogen restoration.
Studies show that inadequate post-exercise fueling prolongs muscle soreness, delays recovery, and impairs subsequent performance. Over time, poor recovery nutrition increases the risk of overuse injuries and burnout.
Nutrition and Sleep
Emerging research suggests that nutrition and sleep are closely linked. Poor sleep alters hunger hormones, increases cravings, and impairs glucose metabolism. Adequate energy and carbohydrate intake, particularly later in the day, may support improved sleep quality in active individuals.
9. Individualize Your Nutrition Strategy
Individual Differences Matter
Body size, sex, age, training intensity, training frequency, and metabolic differences all influence nutritional needs. Research consistently shows large individual variability in how people respond to the same diet.
Some athletes perform best with higher carbohydrate intakes, while others function well with moderate levels. The key is to adjust intake based on performance, recovery, and overall well-being rather than rigid dietary rules.
Monitor and Adjust
Tracking training quality, energy levels, recovery, and body composition provides valuable feedback. Evidence-based nutrition is a dynamic process that evolves as training demands and life circumstances change.
10. Be Consistent, Not Perfect
Long-Term Habits Drive Results
Research on dietary patterns consistently shows that long-term consistency has a greater impact on health and performance than short-term dietary perfection. Occasional lapses do not outweigh the benefits of regular, adequate fueling.
Athletes who maintain stable energy intake, sufficient protein, and adequate carbohydrates over time experience better training adaptations and fewer injuries.
Sustainable Nutrition Wins
A nutrition strategy that is scientifically sound but unsustainable will eventually fail. Evidence supports flexible approaches that prioritize adherence while meeting physiological needs. Consistency, not perfection, is what ultimately drives results.
About the Author
Robbie Wild Hudson is the Editor-in-Chief of BOXROX. He grew up in the lake district of Northern England, on a steady diet of weightlifting, trail running and wild swimming. Him and his two brothers hold 4x open water swimming world records, including a 142km swim of the River Eden and a couple of whirlpool crossings inside the Arctic Circle.
He currently trains at Falcon 1 CrossFit and the Roger Gracie Academy in Bratislava.
