Sports Nutrition: What to Eat Before, During, and After Exercise

Before considering any aspect of nutrient timing or supplementation, the single most important variable in sports nutrition is energy availability — consuming enough total calories to cover both your training demands and your body's basic physiological needs. Chronic low energy availability leads to Relative Energy Deficiency in Sport (RED-S), which impairs hormonal function, suppresses the immune system, reduces bone density, causes muscle loss, and paradoxically deteriorates rather than improves performance over time.

Many athletes, particularly those in aesthetically judged sports or those trying to lose body fat while training, inadvertently under-fuel. The signs are subtle at first — persistent fatigue, declining performance, frequent illness, mood disturbances — before becoming more severe. Energy requirements vary enormously: a recreational gym-goer training three times a week might need 2,200–2,600 kcal/day, while an elite endurance athlete in heavy training might require 4,000–6,000 kcal/day. Using food tracking apps for a few weeks can reveal whether you are chronically under or overeating relative to training load. Getting energy balance right is the prerequisite without which everything else in sports nutrition matters far less.

The primary goal of pre-exercise nutrition is to arrive at your training session with adequate carbohydrate stores (muscle and liver glycogen), appropriate blood glucose levels and a stomach that is neither overfull nor empty. Carbohydrates are the dominant fuel for moderate-to-high intensity exercise; starting a session with depleted glycogen stores significantly impairs endurance, strength and technical performance.

A substantial meal 3–4 hours before exercise should be carbohydrate-rich, moderate in protein and low in fat and fibre to facilitate gastric emptying. Good examples include porridge with banana and yoghurt, pasta with tomato sauce and chicken, or rice with fish and vegetables. A smaller carbohydrate-rich snack 30–60 minutes before exercise can top up blood glucose — a banana, a small bowl of rice cakes, or a sports drink all work. Fat and fibre slow gastric emptying and can cause gastrointestinal discomfort during intense exercise, so pre-workout meals should minimise these. Protein in the pre-workout meal is less critical than carbohydrate for performance, though some evidence suggests it can enhance subsequent muscle protein synthesis particularly for strength-focused sessions.

For exercise lasting less than 60–75 minutes at moderate intensity, water is generally the only in-session nutritional requirement. The body's glycogen stores are sufficient to fuel this duration without supplemental carbohydrates, and solid food is unnecessary and often uncomfortable. For sessions lasting longer than 75–90 minutes at moderate-to-high intensity, carbohydrate intake during exercise extends endurance performance, delays fatigue and maintains mental focus and decision-making quality.

The recommended carbohydrate intake during prolonged exercise is 30–60 g per hour for sessions up to 2.5 hours, and up to 90 g per hour (using a glucose-fructose blend to exploit multiple intestinal transport pathways) for sessions over 2.5 hours. Sports gels, sports drinks, bananas, dates, and rice cakes are all practical in-session options. Hydration should accompany carbohydrate intake — exercising in a dehydrated state amplifies performance decrements. In hot conditions or during very long sessions, electrolyte replacement (particularly sodium) alongside water prevents hyponatraemia (dangerous low blood sodium) and maintains fluid balance better than water alone. For resistance training sessions under 60 minutes, in-session nutrition is usually unnecessary beyond maintaining adequate hydration.

Recovery nutrition serves three main purposes: replenishing depleted glycogen stores, stimulating muscle protein synthesis to repair and build muscle, and rehydrating. The classic advice to consume a protein-carbohydrate meal within 30 minutes of finishing exercise ('the anabolic window') has been somewhat nuanced by later research, but the fundamental principle remains valid, particularly for those training twice daily, for those training fasted, or for maximising competitive performance.

For practical purposes, consuming 20–40 g of high-quality protein within 1–2 hours post-exercise is the most consistently evidence-supported recommendation. Whey protein is the most studied and shows particularly rapid absorption and high leucine content that powerfully stimulates muscle protein synthesis. Whole food sources including chicken, fish, eggs, dairy and soy work equally well for most purposes. Pairing protein with carbohydrate (1–1.2 g/kg body weight) accelerates glycogen resynthesis, which is particularly important when training again within 8–24 hours. Chocolate milk, famously, provides a convenient and research-validated ratio of protein to carbohydrate for post-exercise recovery. Rehydration should aim to replace 150% of fluid lost through sweat (body weight before minus body weight after exercise, converted to litres).

For athletes focused on building muscle or maintaining muscle during fat loss phases, protein quality, quantity and distribution across the day all matter. The current evidence supports consuming approximately 1.6–2.2 g of protein per kilogram of body weight per day for muscle development, with some benefit seen up to 2.4 g/kg for those in caloric restriction. Beyond this range, evidence for further muscle-building benefit is weak.

Equally important to daily total is distribution. Consuming protein in three to four doses of 20–40 g spread across the day (rather than the same total eaten predominantly at one meal) keeps muscle protein synthesis elevated more consistently over 24 hours. Pre-sleep protein — 30–40 g of casein or Greek yoghurt before bed — has good evidence for enhancing overnight muscle protein synthesis and improving morning recovery, particularly for those training in the evening. Complete protein sources containing all nine essential amino acids are more effective than incomplete sources (many plant proteins are low in one or more essential amino acids), which is why vegetarian and vegan athletes need to combine protein sources or rely on complete plant proteins such as soy, quinoa or hemp.

Carbohydrate loading — systematically increasing glycogen stores above normal levels by consuming a very high carbohydrate diet (8–12 g/kg body weight/day) for 1–3 days before endurance competition — is a well-validated strategy for events lasting more than 90 minutes. It has been shown to improve endurance performance by 2–3% in trained athletes by delaying glycogen depletion. It is not relevant for shorter events, strength training or recreational exercise.

Regarding supplements, the evidence base is much thinner than the industry suggests. Creatine monohydrate is the most consistently evidence-supported ergogenic supplement for strength and power sports, increasing maximal strength and high-intensity exercise performance through enhanced phosphocreatine availability. Caffeine (3–6 mg/kg body weight 30–60 minutes before exercise) improves endurance, strength and cognitive performance during exercise with a strong evidence base. Beta-alanine can buffer muscle acidity during high-intensity efforts lasting 1–4 minutes, with modest but consistent performance benefits. Sodium bicarbonate has similar acid-buffering effects. Everything else on the sports supplement market — branched-chain amino acids, glutamine, HMB, testosterone boosters, fat burners — has either weak, inconsistent or frankly fabricated evidence behind claimed performance benefits.