Whether it's a home HIIT session, a morning jog, a spin class, or just 30 minutes of exercise before work - what you eat beforehand affects how you feel and perform.
The science confirms this: research published in the Journal of the International Society of Sports Nutrition shows that consuming carbohydrate and protein before exercise increases muscle glycogen availability, reduces muscle protein breakdown, and facilitates greater training adaptations. Get it wrong and you'll be clock-watching, feeling sluggish, or worse - experiencing that unpleasant stomach feeling mid-burpee.
Here's an evidence-based guide to pre-workout nutrition that works for any type of training.
The Science of Pre-Workout Fuel
Your body stores approximately 2,000 calories of glycogen in muscles and liver - your primary fuel for moderate-to-high intensity exercise. Consuming carbohydrate before training decreases muscular fatigue and spares protein from being used as energy. Aim for 1.4-2.0g protein per kg bodyweight daily for exercising individuals, with pre-workout meals containing approximately 0.25g/kg protein (20-30g for most people) alongside carbohydrates.
Timing Matters (Evidence-Based)
How much and what you eat depends entirely on when you're eating relative to your workout:
| Timing | What to Eat | Example |
|---|---|---|
| 2-3 hours before | Full balanced meal | Chicken, rice & vegetables |
| 1-2 hours before | Smaller meal, lower fat | Porridge with banana |
| 30-60 mins before | Light snack, mainly carbs | Banana or toast with jam |
| Under 30 mins | Very light or nothing | Few sweets, sports drink |
Different Workouts, Different Needs
💪 Strength Training
Lifting weights requires glycogen for power output. Don't train completely depleted - you'll struggle with heavy sets.
- A proper meal 2-3 hours before is ideal
- At minimum, have a banana or toast 30-60 mins before
- Protein isn't critical pre-workout (save it for after)
🏃 Cardio (Under 60 Mins)
Shorter cardio sessions don't need as much fuel. Your existing glycogen stores are usually enough.
- Light snack is sufficient
- Can train fasted if you prefer
- Focus more on hydration
⚡ HIIT / Circuit Training
High-intensity intervals burn through glycogen fast. You need fuel, but not so much that you feel heavy.
- Light meal 1-2 hours before works well
- Avoid anything too heavy - it'll come back to haunt you
- Simple carbs closer to the session
🌅 Morning Workouts
Training first thing means limited time to eat. Some people thrive fasted, others need something.
- Try training fasted for a few weeks - many adapt well
- If you need something: banana, rice cake, or half a slice of toast
- Coffee can help performance and suppress hunger
Quick Pre-Workout Snack Ideas
When you've only got 30-60 minutes before training:
Foods to Avoid Pre-Workout
- High-fat meals - Takes 3-4 hours to digest properly
- High-fibre foods - Can cause stomach issues during exercise
- Spicy foods - Risk of heartburn and discomfort
- Large protein portions - Protein is slow to digest; save it for after
- Carbonated drinks - Bloating and burping mid-workout
- Anything new - Stick to foods you know work for you
Hydration Is Just as Important
Research is unequivocal: 2% body weight loss from dehydration impairs exercise performance - reducing strength by ~5.5%, power by ~5.8%, and endurance by approximately 10%. Here's what to aim for:
- Drink 400-600ml of water 2-3 hours before exercise
- Another 200-300ml 20-30 minutes before
- Don't chug right before - you'll feel it sloshing around
- Your urine should be pale yellow, not dark - that's your hydration indicator
What About Pre-Workout Supplements?
It's an effective ergogenic aid. 3-6mg per kg bodyweight, consumed 60 minutes before exercise, produces performance benefits of approximately 2-3% in most exercise tasks. Around 74% of elite athletes use caffeine before training.
For a 70kg person, that's 210-420mg caffeine - roughly 2-4 cups of coffee. Most other pre-workout ingredients are either underdosed or have minimal evidence. A strong coffee and a banana provides 80% of the benefit at a fraction of the cost. Note: doses exceeding 7mg/kg can cause adverse effects including tremors and GI discomfort.
Evidence-Based Summary
Eat a balanced meal (protein + carbs) 2-3 hours before, or a carb-focused snack 30-60 minutes before. Stay hydrated - 2% dehydration impairs performance. Caffeine (3-6mg/kg, 60 mins before) provides ~2-3% performance boost. The closer to your workout, the smaller and simpler the food should be.
Once your workout's done, nutrition matters too. Check out our guide on what to eat after a workout to maximise your recovery.
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