Before a workout, the goal is available energy without stomach discomfort. A carbohydrate-based snack or small meal one to three hours beforehand works well for most people, such as fruit, toast, oats or a banana. For short, light sessions you may not need anything beyond normal meals, and very heavy meals right before exercise can cause cramps.
After exercise, your muscles use carbohydrate to replace glycogen and protein to repair, so a combination of both is ideal within a couple of hours, for example a meal with rice or potato plus chicken, fish, eggs, beans or yoghurt. Rehydration also matters, especially after sweaty or long sessions.
Exact needs depend on the intensity, duration and your goals, and most casual exercisers can meet them through normal balanced meals rather than special products. Athletes, people with diabetes, or those training intensely may benefit from tailored advice from a sports dietitian.