This week Warren Henricus, 14 Warren asks: 'What should I eat before football practice/match?' Wynnie says: Teenagers can get all the nutrients they need by eating a healthy, balanced diet. However, teen athletes will need to eat and drink more than their less-active friends. Nutrition is the key to unlocking a teen athlete's full potential - if they don't eat enough, their bodies are more likely to break down. Apart from eating a balanced diet which provides enough calories for energy and growth, active teenagers need plenty of water. When you're exercising, your body temperature goes up and you sweat. As sweat evaporates, your skin and the blood cool down. However, if you lose too much water this way and don't replace it by drinking, you can get dehydrated. Dehydration can affect your strength and endurance; you're also more likely to get heat exhaustion and heat stroke if you're dehydrated. Drinking before, during, and after exercising is the best way to stay hydrated - every 15 minutes during activity is best, even if you don't feel thirsty. If you wait until you feel thirsty, you may already be dehydrated. Water is the best choice although sports drinks can benefit some athletes. Sports drinks contain sugar and salts (on the label, it'll say electrolytes). These can help athletes who do an activity for more than an hour, especially in hot weather. Teen athletes need slightly more protein than their less-active friends, but most can get it from a normal diet. It's a myth that athletes need more protein to build big, strong muscles. Muscle growth comes from regular training. Carbohydrates are the best source of fuel for everyday life, including physical exercise by athletes. Sports dietitians advise people to choose starchy, carbohydrate foods, such as rice, sweet and baked potatoes, pasta, bread, fruits, vegetables, peas, beans and lentils. These provide athletes with long-lasting energy and nutrients. Although eating sweets or other sugary snacks just before exercising or competition can give athletes a quick burst of energy, this could also easily make them run out of steam before they've finished their workout. Foods you've eaten over the past few days will provide most of the energy you need on competition day. Watching what you eat in the hours before the event will ensure that you perform to your potential. Try to eat two to four hours before you compete. Something that's easy to digest, such as a chicken sandwich or a bowl of cereal and low-fat milk, is ideal, along with 500 milliletres of water. An hour before the event, a fruit smoothie or sports drink will help to keep you hydrated. Wynnie Chan is a British-trained nutritionist. If you've got a question for her or would like to be featured in this column, e-mail nutrition@scmp.com Warren's diary: Breakfast: Cereal or pancakes, bacon and eggs with orange juice or milk Lunch: Turkey Caesar salad or fried rice with meat Snack: Dried apricots, muesli bar or a chocolate chip muffin Dinner: Rice, meat curry or fish and vegetables (for example, lentils, potatoes, carrots) After dinner: Glass of milk, banana Exercise: About four hours a week of football, a gentle jog at the weekends for about 1/2 hour