What to Eat Before and After Exercise

Exercise nutrition serves two purposes: fuelling performance (energy availability during activity) and supporting recovery (muscle protein synthesis and glycogen replenishment after activity). These goals have different macronutrient priorities.

For fuelling performance, carbohydrates are the primary substrate for moderate to high-intensity exercise. Glycogen (stored glucose in muscle and liver) is the main energy source for any exercise above approximately 65% VO2 max — which includes most gym training, team sports, and interval-based running. Fat is the primary fuel at lower intensities (walking, easy cycling) but becomes limiting as intensity increases.

For recovery, protein is the primary priority — specifically, adequate amino acids to trigger MPS. Carbohydrates support recovery by replenishing glycogen stores, particularly important for athletes training multiple times daily or those doing long-duration endurance events.

The goal of pre-workout eating is to top up energy without causing gastrointestinal discomfort during exercise. A meal 2–3 hours before training provides the most flexibility: it should be relatively high in carbohydrates, moderate in protein, and low in fat and fibre (both slow digestion and can cause discomfort under exertion).

If eating closer to training (30–60 min before), choose a smaller, more easily digested option: a banana, rice cakes with a small amount of peanut butter, or a small portion of oats. Avoid large meals, high-fat foods, and high-fibre foods within 90 minutes of training.

For most people exercising for 45–75 minutes at moderate intensity, pre-workout meals are not dramatically performance-affecting as long as overall daily nutrition is adequate. Fasted training is tolerated well by many people for sessions under 60 minutes and has no significant disadvantage for non-elite trainees.

• 2–3 hours before: normal meal, moderate carbs, moderate protein, low fat
• 1–2 hours before: medium snack, easily digested (oats, banana, toast)
• 30–60 min before: small snack (banana, rice cake, small handful of dates)
• Avoid high fat and high fibre within 90 min
• Hydration: 500ml water 2 hours before, sip during exercise

The 'anabolic window' — the idea that you must consume protein within 30 minutes of finishing exercise or the benefit is lost — is significantly overstated in popular fitness culture. Research shows that MPS remains elevated for at least 24 hours after resistance training, and the most impactful factor is total daily protein intake, not the timing of a single post-workout dose.

That said, consuming 20–40g of protein within 2 hours of training is practical and beneficial. This recommendation is not because the window is closing — it is because training suppresses appetite (making it easier to miss a meal), and early protein intake at least ensures the day's total is on track.

For endurance athletes (long runs, cycling over 90 minutes), post-workout carbohydrate intake becomes more important: 0.8–1.2g of carbohydrates per kg of body weight within 30 minutes begins glycogen resynthesis at the fastest rate, which matters most for people training again within 24 hours.

Even mild dehydration (1–2% of body weight) meaningfully impairs aerobic performance, cognitive function, and mood. For a 75kg person, that is a 750g–1.5kg loss — equivalent to less than one hour of moderate exercise in warm conditions.

Thirst is a reasonable guide under most circumstances but underestimates needs in hot weather, during long exercise, and in individuals who have chronically under-hydrated (they recalibrate their thirst threshold upward). Pale yellow urine is the most practical indicator of adequate hydration.

Sports drinks containing electrolytes are warranted for exercise lasting over 90 minutes or shorter exercise in extreme heat where sodium loss is significant. For most gym sessions under an hour, water is sufficient.