Wendy advises Olympic athletes and England football players on their diet. She is a consultant sports nutritionist to the British Olympic Association, and is a registered dietitian who works with the NHS as a clinical nutrition service manager.
Can I eat more when I'm doing lots of exercise?
If you're doing lots of exercise, you'll use more energy each day than if you did little or none. So if you don’t want to lose body fat, you need to eat more food each day.
But still make sure that you have a balanced diet. Aim for larger portions of carbohydrate-rich foods such as wholegrain pasta, rice, sweet potato, porridge and breakfast cereals.
Learn more about a balanced diet in The Eatwell plate.
Is it better to eat a diet high in starchy carbohydrates or protein when I'm training?
Carbohydrates are the fuel that power your exercise regime.
Protein is needed in moderate amounts for muscle growth and repair, but the main form of energy used during exercise is carbohydrates.
Carbohydrates are the most important fuel for muscles, and an essential energy source for the brain and central nervous system.
Carbohydrates are stored as glycogen in the muscles and liver. These stores are small, so a regular intake of carbohydrate is necessary to keep them topped up. Low glycogen stores will result in poor performance and increase the risk of injury.
The proportions of carbohydrate and protein required will vary depending on the sport, so it's best to seek advice from a qualified professional on your individual requirements.
Learn more in Starchy foods.
How should I time my meals and snacks around exercise?
Once you’ve eaten a meal or snack, allow between one and four hours to pass before you start exercising. Your body needs time to digest. The amount of time will depend on the amount of food you've eaten.
If it's an average meal, eating around two hours before you exercise works well. The meal should be high in carbohydrate, low in fat and low to moderate in protein. Too much protein or fat will slow down the movement of foods from the stomach, and will make you feel uncomfortable.
Food and drink also plays a part in recovering effectively from training. Good recovery is crucial to prevent a midweek slump in energy levels, and to aid muscle growth and repair. When you finish training, aim to have a carbohydrate-rich food or drink within 30 minutes.
Do I need to drink when I exercise?
Dehydration is when the water content in your body falls too low. It can have a major effect on exercise performance. It's important to start any exercise session well hydrated. Do this by drinking water, squash or diluted fruit juice regularly during the course of the day.
For any exercise that lasts longer than 30 minutes, drink fluid while you're doing it. The more you sweat, the more you’ll need to drink.
Water is usually enough for low-intensity exercise up to 50 minutes. For higher-intensity exercise lasting more than 50 minutes, or lower-intensity exercise lasting hours, a sports drink would be of benefit.
The carbohydrates in a sports drink will help to maintain energy levels, and the salt helps to keep you hydrated.
Learn more in Water and drinks.
My friend exercises to lose weight, but I exercise to build muscle. Should our diets be different?
Yes. To lose weight, or more specifically body fat, the amount of energy that you consume has to be less than the amount of energy you burn. You’ll need a diet and exercise regime that makes this happen.
There are key steps you can take to reduce the energy content in your daily diet. Reduce fat, which is the most concentrated source of energy, and reduce alcohol. Eat fewer sugary foods, such as sweets, chocolates, cakes, biscuits and sugary drinks, and eat regular but smaller portions of complex carbohydrate foods, such as wholegrain bread, rice and pasta.
Protein foods such as chicken, fish, lean red meat and low-fat dairy foods should be included in moderate amounts. Eat lots of fruit and vegetables. It's important to control portion sizes, too.
Learn more Start losing weight.
But to build muscle you need to combine resistance training (also called strength training) with a diet that includes enough energy to enable your body to make muscle.
This energy should come mainly in the form of carbohydrate-rich foods, but you’ll also need a little more protein to provide muscle. Large amounts of protein aren't required.
A particularly effective approach is to eat small amounts of protein and carbohydrate before and after the resistance training session. A low-fat milkshake can work well.
Should I take extra supplements when I'm playing sport?
There are many different supplements on the market. Some of them are based on solid research, and others aren't. Athletes need to consider supplements with extreme caution. In the past, some supplements were found to have been contaminated with banned substances.
First, ensure that you have a balanced, healthy diet that suits your sport. Consult a registered dietitian or nutritionist with expertise in sports nutrition. They can assess this and advise you on particular supplements.