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Sport and exercise

Eating well for exercise.

We should all aim to eat a healthy, varied diet based on the principles of the Eatwell Guide, and this is also the case when you are active. 


When physically active, your body will use up more energy (calories). This can help with weight control or if you are not looking to lose weight, you may find you need more food to replace the extra energy used. It is also important to keep well hydrated.


Eating well for physical activity and sport can have many benefits including:

  • Allowing you to perform well in your chosen sport or activity
  • Reducing the risk of injury and illness
  • Ensuring the best recovery after exercise or a training programme

However, the dietary patterns that will best suit an individual will depend on the amount and intensity of activity. This can range from those who are just starting to get more active, those meeting the activity guidelines (of 150 minutes moderate activity per week), those who are active at higher levels (such as those training for an endurance event such as a marathon or doing organised team sports) or professional athletes.


For professional athletes, getting personalised nutrition advice from a qualified sports nutritionist or dietitian is likely to be an important part of their training support.


The most effective weight loss programmes include both a healthy and balanced diet and increased physical activity. It is also important to be active to keep weight off after weight loss.


Zoe Hill, Nutrition Scientist, British Nutrition Foundation

Physical activity when losing weight

Doing physical activity will increase your energy expenditure

Energy is required during exercise to fuel the contracting muscles, increased breathing, heart rate and metabolism.

The benefits of physical activity go beyond just burning off calories and can help preserve muscle as you lose weight and increase the proportion of muscle in the body. We also know that physical activity, and spending less time sitting, can reduce your risk of developing several chronic diseases, such as heart disease.

Excerise and nutrition FAQs

Carbohydrate is important as an energy source during exercise. Having very low intakes of carbohydrate when exercising can cause low energy levels, loss of concentration, dizziness or irritability.


Because carbohydrate is important for providing energy during exercise, there is a benefit in ensuring enough is consumed. This is especially for high-intensity exercise where some studies have shown that performance is reduced when carbohydrate intakes are low. Some studies in specific exercise scenarios such as lower intensity training in endurance runners, have found beneficial effects of low carbohydrate diets on performance. However, these results have not been consistent and so at the moment we do not have enough evidence to show that low-carbohydrate diets can benefit athletic performance.

Supplements are one of the most discussed aspects of nutrition for those who are physically active. However, whilst many athletes do supplement their diet, supplements are only a small part of a nutrition programme for training. Athletes are advised to follow a ‘food first’ approach to avoid using supplements that are not needed or could result in nutrient intakes that are too high. For most people who are active, a balanced diet can provide all the energy and nutrients the body needs without the need for supplements.


Sports supplements can include micronutrients, macronutrients or other substances that may have been associated with a performance benefit, such as creatine, sodium bicarbonate or nitrate. The main reasons people take supplements are to correct or prevent nutrient deficiencies that may impair health or performance; for convenient energy and nutrient intake around an exercise session; or to achieve a direct performance benefit. Whilst adequate amounts of protein and carbohydrate are both essential in maximising performance and promoting recovery, most people should be able to get all the nutrients they need by eating a healthy, varied diet and, so supplements are generally  not necessary.


For athletes, supplementing the diet may be beneficial, possibly on performance, on general health or for reducing injury and illness risk. However, there is not much research on many of the commonly used supplements, and there are only a small number of supplements where there is good evidence for a direct benefit on performance, including caffeine, creatine (in the form of creatine monohydrate), nitrate and sodium bicarbonate. 


Even in these cases, the benefits on performance vary greatly depending on the individual and there is only evidence for a benefit in specific scenarios. This means that any athletes considering supplementation will need to weigh the potential benefits with the possible negative impacts, such as negative effects on general health or performance, risk of accidental doping or risks of consuming toxic levels of substances (such as caffeine). The advice to consider supplementation for a performance benefit is for high performance athletes and should be carried out alongside expert advice from qualified sports nutritionists or dietitians.

It is a common myth that consuming lots of excess protein gives people bigger muscles. Quite often, people taking part in exercise focus on eating lots of protein, and consequently may not get enough carbohydrate, which is the most important source of energy for exercise. The main role of protein in the body is for growth, repair and maintenance of body cells and tissues, such as muscle. Fifteen to 25g of high-quality protein has been shown to be enough for optimum muscle protein synthesis following any exercise or training session, for most people, and any excess protein that is ingested will be used for energy. The recommendations for daily protein intake are set equally for both endurance training and resistance training athletes, so higher intakes are not recommended even for those exclusively trying to build muscle. Any more protein than this will not be used for muscle building and just used as energy.


So although protein supplementation has become increasingly popular for muscle building, it is generally unnecessary. For most active people, the body’s protein needs can be easily achieved from a healthy, varied diet, with good choices of high quality, lean protein foods being incorporated into meals and snacks. However, after competition or an intense training session, high quality protein powders can be more convenient and transportable. Especially when there is limited access to food or if an individual does not feel hungry around exercise.

Vegetarian and vegan diets for athletes

There has been a rise in media interest around the use of vegetarian or vegan diets to improve sporting performance. However, this remains a new area for research and there have only been a few studies that have looked at vegan/vegetarian diets for athletes.


To date, there is no clear evidence to suggest that vegetarian or vegan diets impact performance differently to a mixed diet, although it is important to recognise that whatever the dietary pattern chosen, it is important to follow a diet that is balanced to meet nutrient requirements. More research is needed to determine whether vegetarian or vegan diets can help athletic performance.


For the general population, eating a more plant-based diet has the potential to benefit health. This doesn’t mean you have to cut out animal products completely but to include more plant foods such as wholegrains, beans, lentils, nuts and seeds. More plant-based diets can provide a wide variety of nutrients and natural phytochemicals, plenty of fibre and tend to be low in saturated fat, salt and sugar. More information on vegetarian and vegan diets is available on our page on this topic.


The main role of carbohydrates in physical activity is to provide energy. For athletes, if their diet does not contain enough carbohydrate, it is likely that their performance and recovery will be impaired, as carbohydrate is the key fuel for the brain and for muscles during exercise.


The body can store carbohydrates in the muscles and liver as glycogen and use these stores as a source of fuel for physical activity. These glycogen stores are limited, so for those training at a high level, it is important to be fully fuelled at the start of any exercise. 


Glycogen is the main source of energy at the start of exercise and during short bursts of exercise. If you are doing high intensity training for long periods and your glycogen stores are not sufficient you may feel tired, lack energy and not be able to perform at your best. So, regular intake of carbohydrate-rich foods can be important in this case to keep stores topped up. The correct food choices can help ensure the body has enough energy for activity, as well as help aid recovery.

Starchy foods are an important source of carbohydrates in our diet. Wholegrain varieties also provide fibre, and a range of vitamins and minerals including B vitamins, iron, calcium and folate. Sugars are also carbohydrates and the amount of ‘free sugars’ (those added to foods and drinks or in fruit juices, honeys and syrups) we consume should be limited.


The amount of carbohydrate you need will depend on the frequency, type, duration and intensity of physical activity you do. Competitive sports people and athletes will likely need more carbohydrates than an average gym user to match the intensity of their activity level.   


If you are active at around the current recommended levels (150 minutes of moderate activity or 75 minutes of high intensity activity plus two sessions of muscle strengthening activities per week), then you can follow general healthy eating guidance to base meals on starchy carbohydrates, choosing wholegrain and higher fibre options where possible. For information about portion sizes of starchy foods you can use our Get portion wise! portion size guide.


For athletes and individuals who are recreationally active to a higher level (such as training for a marathon), consuming additional carbohydrate may improve performance. It is a good idea to have some carbohydrate both before and after exercise to ensure you have enough carbohydrate at the start of training and to replenish glycogen stores after exercise. In longer duration, high intensity exercise (60-90 minutes or more), such as a football match or a marathon, consuming some carbohydrate during exercise can also improve performance, for example in the form of a sports drink.

Intensity of activity Recommended intake (per kg body weight, per day)

Light 3-5g

Low intensity/ skill based

Moderate 5-7g

Moderate exercise programme

High 6-10g

Endurance programme

Very high 8-12g

Extreme commitment (>4 hours/day moderate-high intensity exercise)

Carbohydrate content



Serving size

Carbohydrate content (g) per serving size

Wholewheat pasta (boiled)






Rice, wholegrain (boiled)



Baked potato with skin



Wholemeal bread






Crumpet, toasted














Protein is important in sports performance as it can boost glycogen storage, reduce muscle soreness and promote muscle repair. For those who are active regularly, consuming a portion of protein at each mealtime and spreading protein intake out throughout the day may be beneficial.


As some high protein foods can also be high in saturated fat, for example fatty meats or higher fat dairy products, it is important to choose lower fat options, such as lean meats or fish. Most vegans get enough protein from their diets, but it is important to consume a variety of plant proteins to ensure enough essential amino acids are included.. More information on vegetarian and vegan diets is available on our page on this topic.


There may be a benefit in increasing protein intakes for athletes and those recreationally active to a high level. But the importance of high protein diets is often exaggerated for the general population.

It is a common misconception that high protein intakes alone increase muscle mass and focussing too much on eating lots of protein can mean not getting enough carbohydrate, which is a more efficient source of energy for exercise. It is important to note that high protein intakes can increase your energy (calorie) intake, which can lead to excess weight gain.


The current protein recommendations for the general population are 0.75g of protein per kg of bodyweight per day for adults and most people are consuming more than this. so it’s unlikely that you need to eat extra protein if you are active within the current guidelines of 150 minutes of moderate intensity activity per week. If you take part  in regular sport and exercise like training for a running or cycling event or lifting weights regularly, then your protein needs may be slightly higher than the general population, to promote muscle tissue growth and repair.


For strength and endurance athletes, protein requirements are increased to around 1.2-2.0g of protein per kilogram of bodyweight per day. The most recent recommendations for athletes from the American College of Sports Medicine (ACSM) also focus on protein timing, not just total intake, ensuring high quality protein is consumed throughout the day (after key exercise sessions and around every 3–5 hours over multiple meals, depending on requirements). In athletes that are in an energy deficit, such as team sport players trying to lose weight gained in the off season, there may be a benefit in consuming protein amounts at the high end, or slightly higher, than the recommendations, to reduce the loss of muscle mass during weight loss.


Timing of protein consumption is important in the recovery period after training for athletes. Between 30 minutes and 2 hours after training, it is recommended to consume 15-25g of protein alongside some carbohydrate. Although they may be useful for convenient protein intakes around exercise, protein supplements cannot provide all the different components found in protein-rich foods so focussing on a ‘food first’ approach is best. A whey protein shake contains around 20g of protein, which you can get from half a chicken breast or a small can of tuna. For more information on protein supplements, see the supplements section.

Protein content


Food source

Serving size

Protein content (g) per serving size

Chicken breast grilled



Salmon fillet grilled



Rump steak grilled



Tuna canned in brine



Baked beans









Half fat cheddar cheese



Semi skimmed milk




How to stay well hydrated

Water is essential for life and hydration is important for health, especially in athletes and those who are physically active, who will likely have higher requirements. Drinking enough fluid is essential for maximising exercise performance and ensuring optimum recovery. Exercising raises body temperature and so the body tries to cool down by sweating. This causes the loss of water and salts through the skin.


The amount an individual sweats varies from person to person and depends on:

  • Intensity and duration of exercise – longer and higher intensity exercise can cause greater sweat loss
  • Environmental temperature – in hot, humid conditions sweat loss can increase.
  • Clothing – the more clothing that is worn, the quicker you are likely to heat up which may cause greater sweat loss.
  • Genetics – some people sweat more than others.

Generally, the more a person sweats, the more they will need to drink. Average sweat rates are estimated to be between 0.5–2.0L/hour during exercise.


Dehydration can cause tiredness and affect performance by reducing strength and aerobic capacity (especially when exercising for longer periods). So, especially when exercising at higher levels or in warmer conditions, it is important to try and stay hydrated before, during and after exercise to prevent dehydration. In most cases, unless training at a high intensity for over an hour, water is the best choice as it hydrates without providing excess calories or the sugars and acids found in some soft drinks that can damage teeth.


For those who are recreationally active to a high level, or for athletes, managing hydration around training or competition is more important. The higher intensity and longer duration of activity means that sweat rates tend to be higher. Again, the advice for this group would be to ensure they drink fluids before, during and after exercise. Rehydration would usually involve trying to drink around 1.25-1.5L of water for every kg of body weight lost during exercise through sweat. However for longer, more intense exercise (longer than 60 minutes), there may be extra benefit in consuming drinks containing some carbohydrates, and other electrolytes including sodium, during exercise, as this is when carbohydrate stores may substantially decrease, and sodium losses can be higher (such as marathon/long distance running, football games or competitive swimming).


Below are some examples of other drinks, other than water that may be used by athletes, both recreational and elite.

  • Sports drinks: sports drinks contain carbohydrates in the form of glucose, as well as electrolytes such as sodium. Sodium will replace any that has been lost from sweating and enhance rehydration, and glucose will replenish carbohydrate stores. Sports drinks have been shown to help endurance performance and recovery for active individuals performing endurance exercise over a longer duration (60 minutes or more) (e.g. participating in a marathon). However, it is important to remember that sports drinks are like other soft drinks that contain sugars. This means that they can be high in calories and contribute to tooth decay, so they are only suitable if taking part in high-level endurance sports or if sweat loss is high.


Sports drinks can be expensive compared to other drinks; however it is easy to make them yourself! To make your own isotonic sports drink, mix 200ml fruit squash (containing sugar rather than sweeteners), 800ml water and a pinch of salt.


  • Milk: Skimmed or semi-skimmed milk has been used in some studies as a post-exercise recovery drink. It contains minerals that can replace those lost via sweating, as well as providing nutrients involved in muscle function and bone health (potassium and calcium). It also naturally contains high quality protein and some carbohydrate in the form of lactose and is relatively cheap to buy.


Energy drinks: are not designed to replace the electrolytes lost in sweat and may contain other ingredients with stimulant properties, such as caffeine. As some are high in sugars, they can increase the risk of tooth decay and contain energy, which may cause weight gain if consumed in excess.


Fat is essential for the body in small amounts, but it is also high in calories. Consuming too much fat can lead to excess calorie intake which can lead to weight gain over time, so this is a concern if you’re trying to control your weight. 


The type of fat consumed is also important. Studies have shown that replacing saturated fat with unsaturated fat in the diet can reduce blood cholesterol, which can lower the risk of heart disease and stroke. Fat-rich foods usually contain a mixture of saturated and unsaturated fatty acids but choosing foods that contain higher amounts of unsaturated fat and less saturated fat, is preferable as most of us eat too much saturated fat. Find more information on our pages on fat.


There is ongoing research on the effects of higher fat/lower carbohydrate diets on athletic performance, and debate about the potential effects for different types of sporting events. For the general population, the advice would be to stick to the population guidelines stated above.

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Please note that advice provided on our website about nutrition and health is general in nature. We do not provide any individualised advice on prevention, treatment and management for patients or their family members.