Proper nutrition is the foundation of successful running, whether you're training for your first 5K or your tenth marathon. What you eat affects your energy levels, recovery, and long-term health as a runner. This guide covers the essential principles of runner nutrition to help you fuel your training effectively.
The Runner's Energy Systems
Understanding how your body produces energy during running helps inform your nutritional choices. Your body primarily uses two fuel sources: carbohydrates and fats.
During low-intensity running, your body primarily burns fat for fuel. As intensity increases, you shift toward greater carbohydrate use. High-intensity efforts like tempo runs and intervals are almost entirely fuelled by carbohydrates.
Your body can store around 2000 calories worth of carbohydrates in the muscles and liver as glycogen, while fat stores are essentially unlimited. This is why carbohydrate intake becomes critical for longer, harder efforts, as depleting your glycogen stores leads to the dreaded "bonk" or "hitting the wall."
Daily Nutrition Foundations
Your day-to-day eating habits form the foundation of your running performance. While you might pay special attention to pre-run and post-run nutrition, what you eat the rest of the time matters just as much.
Carbohydrates
Carbohydrates are the primary fuel for running and should form a significant portion of a runner's diet. The exact amount depends on your training volume: light training days might require 3-5 grams per kilogram of body weight, while heavy training periods may need 7-10 grams per kilogram.
Focus on complex carbohydrates like whole grains, vegetables, and legumes for most of your intake, with simple carbohydrates reserved for during and immediately after running when quick energy is needed.
Protein
Protein is essential for muscle repair and adaptation to training. Runners should aim for approximately 1.4-1.8 grams of protein per kilogram of body weight daily. Distribute protein intake throughout the day rather than consuming it all in one or two meals.
Good protein sources for runners include lean meats, fish, eggs, dairy products, legumes, and for vegetarians, combinations of grains and legumes to ensure complete amino acid profiles.
Fats
Healthy fats support hormone production, provide insulation, and serve as a fuel source for lower-intensity running. Aim for fats to comprise about 20-35% of total calories, focusing on unsaturated sources like olive oil, avocados, nuts, and fatty fish.
Pre-Run Nutrition
What and when you eat before running affects your comfort and performance. The goal is to start your run fuelled but not feeling heavy or full.
Timing
For most runners, eating a substantial meal 2-4 hours before running allows enough time for digestion. A smaller snack can be eaten 30-60 minutes before if needed, but keep it easily digestible.
Composition
Pre-run meals should be high in carbohydrates, moderate in protein, and low in fat and fibre. Fat and fibre slow digestion and can cause gastrointestinal discomfort during running.
Good pre-run meal options include oatmeal with banana, toast with jam, rice with chicken, or a smoothie with fruit and yoghurt. Experiment during training to find what works best for your digestive system.
Fasted Running
Some runners prefer training on an empty stomach, particularly for easy morning runs. This is generally fine for runs under an hour at low intensity. However, for quality sessions or longer runs, pre-run fuel improves performance and should be prioritised.
Fuelling During Runs
For runs under an hour, you typically don't need to consume calories during the run if you started well-fuelled. As run duration increases, mid-run nutrition becomes increasingly important.
When to Start Fuelling
For runs over 90 minutes, begin consuming carbohydrates within the first hour, before you feel depleted. Aim for 30-60 grams of carbohydrates per hour for runs of 1-2.5 hours, and up to 90 grams per hour for longer efforts.
What to Eat
During running, easily digestible simple carbohydrates work best. Options include energy gels, sports drinks, chews, or real food like dates, bananas, or jam sandwiches. Whatever you choose, practice with it in training before racing to ensure it sits well in your stomach.
Post-Run Recovery Nutrition
The 30-60 minutes after running is a critical window for recovery nutrition. During this time, your muscles are primed to absorb nutrients and begin the repair process.
The Recovery Window
Aim to consume a combination of carbohydrates and protein within 30 minutes of finishing a hard or long run. A ratio of roughly 3:1 or 4:1 carbohydrates to protein is optimal for glycogen replenishment and muscle repair.
Recovery Options
Good post-run recovery options include chocolate milk (a classic that provides an excellent carbohydrate-protein ratio), a smoothie with fruit and protein powder, yoghurt with fruit and granola, or a sandwich with lean protein.
If you can't stomach solid food immediately after running, a recovery drink provides the necessary nutrients in an easier-to-digest format.
Hydration and Nutrition
Hydration is intimately linked with nutrition. Dehydration impairs the transport of nutrients to muscles and the removal of waste products. It also reduces the effectiveness of carbohydrate absorption during running.
Include sodium with your during-run nutrition, particularly on runs over 90 minutes or in hot conditions. Sodium aids fluid absorption and helps prevent hyponatremia (dangerously low blood sodium levels).
Weight Management for Runners
Many runners are interested in optimising their weight for performance, but this must be approached carefully.
Under-fuelling is a significant problem in running, particularly among those trying to lose weight while training. Chronic energy deficiency leads to hormonal disruption, increased injury risk, and impaired performance.
If weight loss is a goal, aim for a modest caloric deficit of 300-500 calories per day and never restrict calories on days with hard training or long runs. Prioritise fuelling your training properly and let any weight loss happen gradually.
Supplements for Runners
While whole foods should form the foundation of runner nutrition, certain supplements may be beneficial in specific circumstances.
Vitamin D supplementation is worth considering for runners in southern Australia during winter when sunlight exposure is limited. Iron supplementation may be necessary for runners with diagnosed deficiency, particularly female runners and vegetarians. Caffeine has well-documented performance benefits, particularly for longer efforts.
For most runners eating a varied, adequate diet, multivitamins and other supplements provide minimal benefit. Money is better spent on quality whole foods.
Developing Your Nutrition Strategy
Effective runner nutrition is highly individual. What works perfectly for one runner may cause problems for another. Use the principles outlined here as a starting point, then experiment and refine based on your own responses.
Keep a food and training diary to identify patterns. Note what you eat before runs that go well and those that don't. Pay attention to energy levels, digestive comfort, and recovery quality as indicators of whether your nutrition strategy is working.