What and how much you eat before training can make a big difference to your workout. Choosing the wrong foods, eating too much or too little, or eating at the wrong time can affect your performance and leave you feeling hungry, uncomfortable or unwell. Eating the right pre-exercise meal at the right time ensures that you will be able to perform at your best.
When to eat?
The ideal time for a pre-exercise meal is 2 – 4 hours before your workout because its early enough to digest the food, yet late enough that this energy won’t be used up by the time you begin exercising. In a study at the University of North Carolina, athletes who ate 3 hours before a run were able to exercise longer than those who ate 6 hours beforehand.
Leaving a longer gap than 4 hours means you will almost certainly feel hungry and light headed during training, and run low on energy. On the other hand, eating a meal too close to training could make you feel uncomfortable, ‘heavy’ or nauseous, and also leave you lacking in energy as the blood supply diverts to the digestive organs instead of the muscles.
In practice, the exact timing of your pre-exercise meal will probably depend on constraints such as work hours, travel and session times. Try to plan meals as best you can around these commitments. For example, if you train at 7 o’clock, plan to eat a meal between 3 o’clock and 5 o’clock. If you want to train earlier, then you should eat a smaller meal, which is easier to digest. You should feel comfortable, neither full nor hungry.
If you train first thing in the morning you should try to have a light snack and drink before you head off. This will make a big difference to your performance. Try a cereal bar; a slice of toast; a small bowl of cereal; a couple of mini-pancakes or a banana. Always a have a drink – water is the best choice. You will have lost a lot of fluid in the night and need to rehydrate before training. If you really cannot face food first thing, a sports drink, fruit juice (diluted half and half with water), or a low fat milk-based drink will provide energy to fuel your muscles during training. Persevere – you will soon get used to the feeling of food and drink in your stomach early in the morning and find that you’ll be able to train harder and longer. Another option is to have a larger supper the night before and a light snack or fluids prior to your early morning session.
How much?
The size of your meal depends on three factors: your size, the length and intensity of your workout and the timing of your meal. The heavier you are and the longer your workout, the larger the pre-exercise should be. The closer your pre-exercise meal is to your workout, the smaller it must be. If you are able to eat four hours before your workout, you can probably consume 600 – 800 calories. If you can eat just two hours before your workout, eat a smaller meal of 300 – 400 calories. You should feel neither hungry at the end of your workout nor full at the start of your session. However, some athletes can manage eating closer to training, especially when there is little recovery time from a previous training session. In this case, liquid meals (such as meal replacement drinks and milk shakes) are a good option.
Should I exercise on an empty stomach if I am trying to lose weight?
The theory behind this is that by not eating before a workout – and exercising with lower blood glucose levels – forces the muscles to burn proportionally more calories from fat and less from carbohydrate. While this is true up to a point, it doesn’t mean you’ll shed weight faster. Exercising with low blood glucose levels can induce early fatigue, which results in an overall lower calorie burn. Also, skipping a pre-workout meal or snack may leave you so hungry that you over eat after the session. What matters is your daily energy balance: consuming fewer calories than you burn throughout the day.
What to eat?
Around 60 – 80 per cent of the calories in your pre-exercise meal or snack should come from carbohydrates. The carbohydrates in this meal will raise blood sugar, top up muscle and liver glycogen levels and aid performance during training. Indeed, many studies have shown eating a carbohydrate-rich diet before exercise increases endurance and performance. Conversely, an inadequate carbohydrate intake results in low muscle stores and reduced endurance.
Eating carbohydrate-rich foods that are more slowly digested and absorbed (low GI) will help maintain blood sugar levels during your workout, increase your endurance and help delay fatigue. Studies have shown that athletes are able exercise considerably longer after eating a low-GI meal compared with a high-GI meal. Good options include pasta, wholegrain bread, porridge, beans, lentils and brown rice.
You should include a little protein in your pre-training meal: chicken, fish, cheese, egg, milk, yoghurt, beans, lentils or nuts. This will help lower the overall GI of the meal as well as help reduce muscle breakdown during exercise, and improve performance. Avoid too much fat (ie. fried foods, sausages, burgers and chips) as it delays digestion and may make you feel uncomfortable during training. Porridge, cereal with milk, a jacket potato with beans, or a light pasta meal would be suitable pre-workout meals.
Pre-training meals
- Jacket potato with a little cheese, tuna or baked beans plus salad
- Pasta with tomato-based sauce or pesto, a little cheese; plus vegetables
- Rice, pasta or noodles with chicken, fish or beans; plus vegetables
- Porridge with milk, honey and raisins
- Wholemeal sandwich/roll/ wrap with tuna/ cheese/ chicken/ peanut butter, and salad
Pre-training snacks
If you don’t have time for a meal, have a snack 30 minutes before training with a drink of water.
- One or two bananas
- A handful of dried fruit and a few nuts
- One or two cereal or granola bars (oat-based)
- A pot of fruit yoghurt and some fresh fruit
- One or two slices of bread or toast with honey
Can sugar provide a pre-exercise energy boost?
Sugar-rich foods and drinks raise blood sugar levels, which in turn triggers the release of insulin to remove sugar from the bloodstream. When these levels are raised just before exercise there is the potential for a rebound drop in blood glucose levels (hyopglycaemia) during exercise. Typical symptoms include light-headedness, nausea, and early fatigue during exercise.
Avoid this by consuming only small amounts of sugar before exercise – less than 25g generally produces a moderate increase in blood sugar – or opting for a food or drink with a lower GI. If you need a pre-training energy boost, it’s safer to choose foods, such as bananas, dried fruit, and cereal bars that are less likely to cause rapid increases in blood sugar and insulin levels.
What to drink?
It’s crucial that you are fully hydrated before you begin training otherwise you risk dehydration early in the session. This can affect your performance, causing early fatigue, headache, nausea and dizziness.
Prevention is better than cure. If you train in the evening, ensure you drink plenty of water during the day. If you train early in the morning, have a drink upon rising. You will know if you are properly hydrated from the colour of your urine. It should be pale straw-coloured, not deep yellow, and should not have a strong odour. You can make up for any previously incurred fluid deficits by consuming 400 – 600 ml about two hours before training and continuing to drink little and often during the warm up.
When it comes to choosing the best pre-exercise drink, water is one of the best ways of hydrating the body. Opt for a sports drink if you haven’t eaten anything – in which case the sugars in the drink will help maintain blood sugar levels and fuel the muscles. Otherwise, water is a perfectly good pre-exercise choice together with a pre-exercise meal or snack.