Just as you wouldn’t set off on a long drive very low on fuel, you may need to top up your personal tank before training to get the most from a workout.
Your goal is to have enough stored glycogen from carbohydrates when you start training to sustain performance throughout. If you exercise first thing, glycogen in the liver has been depleted overnight, although some is still present in muscles if your diet generally contains enough carbohydrate. Exercising on a full stomach can be uncomfortable, as blood is directed away from your digestive system.
BEFORE EXERCISING
The consensus is to eat a meal 2–4 hours before working out, where possible. An ideal pre-workout meal is mainly carbohydrate with some protein and a little fat; for example, salmon, white rice, and vegetables roasted in olive oil. If you train early and don’t have the time or appetite, try a more carb-heavy meal the night before. If you’re exercising sooner, or need to top up, a snack (like white toast and honey or fruit salad) 1–2 hours beforehand gives a burst of energy for fuel and is quickly absorbed. With under an hour, stick to liquids like smoothies or sports drinks. Experiment to find the optimal timing for your activity, schedule, and digestion.DURING EXERCISE
Water should suffice for 45–75-minute sessions. After an hour, you may want to consume around 30g of carbs per hour for two hours, increasing to 60g per hour for the next 2–2.5 hours. Gels and sports drinks can help maintain blood sugar levels, but can also contribute to stomach upset during endurance activities like distance running; practise what works for you.