Your choice depends on your activity or sport. Drinks that contain specific carbohydrates are a practical choice for most people as they provide liquid at the same time. If you decide to eat food, e.g. during a walk, bike ride or run, you must carry it with you and make sure it is tasty and easy to eat.
The ideal workout-foods for exercising for longer than 60 minutes are energy bars, grains or breakfast bars, energy gels, raisins or sultanas, bananas and biscuits (with little fat). Eat this food with a lot of water.
The size of the bars, gels and biscuits varies. Check the label for the carbohydrate content and calculate how much you need to take in 30-60g per hour. Choose products with a fat content of less than 5g per portion.