This site is intended for health professionals only

Eating for a healthy active lifestyle

Samantha Stear
PhD MSc BSc
Registered sport and exercise nutritionist
The Sugar Bureau
W:www.sugar-bureau.co.uk

It seems we are told two key things with regard to our health: eat a healthy balanced diet and take part in regular exercise. These two things are, however, not separate - you can't keep up a regular exercise programme without fuelling it with the right diet. And, if we wanted to take it a stage further and rank one above the other, there is an increasing amount of scientific evidence pointing towards exercise as being the most important component to enhance life quality and expectancy. So, why is exercise so important for health?  And how can we best fuel a healthy, active lifestyle?

Fit and healthy
In a world where diseases such as diabetes and obesity are on the increase, it has become even more important that we all make physical activity part of our everyday life. For those who need to lose weight or want to avoid becoming overweight, the best way, both scientifically and for health, is to increase physical activity levels and reduce dietary fat intake. However, even if the individual doesn't lose weight, but becomes fitter, it would help to avoid the many health complications of being overweight. In fact, research shows that people who are fit but overweight have a lower risk of dying from all causes, including heart disease, than people who are unfit but skinny. Taking part in regular physical activity also helps reduce the risk of developing numerous diseases such as cardiovascular disease, type 2 diabetes, osteoporosis and certain cancers. Plus, it is important not to forget the important role that physical activity plays in mental wellbeing, by making us feel better about ourselves, and also by helping reduce stress, ­anxiety and feelings of depression.
Therefore, the recommendation that everyone should accumulate 30 minutes or more of physical activity on five or more days of the week is thoroughly justified. The largest health benefits will be gained by people who are currently sedentary getting involved in some form of physical activity. But it's also important for people who are active to focus on the health benefits that accompany an active lifestyle and use these benefits as a motivational tool to keep them being active and possibly increase activity levels. Physical activity is probably the primary key to health, but diet must be optimised to fuel our activities to enable us to reap the benefits of good health.  

Eating for energy
A healthy balanced diet is essential for good health, for an elite athlete or for someone who enjoys working out to keep fit. Whatever the sport or fitness regime, making informed dietary choices is essential for optimising performance. It doesn't matter whether the aim of exercise is to improve performance, keep fit, control weight or for health reasons, the principles are the same. 
The key to making a diet healthy and balanced is to ensure it provides adequate energy from the consumption of a wide variety of commonly available foods to meet carbohydrate, protein, fat and micronutrient needs for both health and exercise. Above all, it's fundamental that we get energy intake right. Too much and body fat increases, but too little and there is a risk of nutrient deficiency that will impair both health and performance.
The major nutrient to focus on is carbohydrate. This is true even for less active individuals whose energy expenditure is low and for whom the need to maintain an optimal body weight by energy restriction is greater. So, why the emphasis on carbohydrate? Well, no matter what type of exercise is done, the body will always use some glucose for energy. Glucose is formed from the breakdown of carbohydrates - the sugars and starches in the diet - and is stored as glycogen. However, the body can store only a limited amount of glycogen, so the stores need to be kept topped-up to avoid fatigue. If people don't eat enough carbohydrate and continue to exercise, they will soon become sluggish and dizzy, and that's certainly not going to help keep motivation high - they are more likely to give up at the first hurdle! 
As the amount of physical activity increases, the body uses more glucose, and more carbohydrates must be eaten to replenish stores. Therefore, physically active people need to consume a diet where more than half of it (60-70%) comes from carbohydrate foods. The bulk of carbohydrate intake should come from the starchy sources such as bread, rice, potatoes and pasta, while the rest can come from more sugary sources such as sugar, fruit and juices. However, as most carbohydrate foods, such as pasta or sugars, are eventually broken down into glucose, one type is not intrinsically better than the other. People who are exercising regularly need to eat a lot of carbohydrates, but there is only so much bread and pasta you can eat, so this is where sugary snacks and drinks have a useful role to play, both in providing energy before exercise and in helping to restock glucose stores after exercise for the next workout.
Although 2-3 hours should be allowed after a large meal before exercising, a high-carbohydrate snack within 30 minutes of training has several benefits. Eating 25-50g of rapidly absorbed carbohydrate just before exercise will not only improve performance but will also help maintain blood glucose levels and so prevent feelings of lightheadedness (see Table 1). It's also a good idea to eat some carbohydrates within 2 hours of exercise to help restock those glucose stores. There are plenty of portable high-carbohydrate snacks to choose from: bagels, honey or jam sandwiches, cereal bars, bananas, watermelon, dried fruit, Jaffa cakes, jelly beans, Liquorice Allsorts, juice or a sports drink.

[[NIP18_table1_62]]

Liquid assets
Maintaining hydration is also essential, and it is important to start each training session well hydrated.  Where necessary, hydration should be maintained by drinking during exercise, but not so much that weight is gained due to excessive fluid intake. Environmental conditions and how much an individual sweats will determine fluid needs - the more someone sweats, the more fluid is lost, the more should be drunk to replace the fluid lost. Water is fine for low-to-moderate intensity exercise of less than an hour, but, as the duration and intensity of the exercise increases, then the need for carbohydrate supplementation is also increased. Sodium intake should also be considered where sweat losses are high, particularly when exercise lasts more than two hours. One of the simplest ways to achieve this is by drinking a sports drink - which supplies water, sugars and salt - to help optimise performance.  

Supplementary thoughts
Protein foods are important for the growth and repair of tissues. However, a varied diet containing everyday foods that meets energy needs is likely to supply more than enough protein. Although only animal sources contain all the essential amino acids, a well-chosen vegetarian diet that combines various plant foods can provide protein needs without the need for dietary supplements.
Although we need to keep an eye on fat intake, particularly saturated fat, this doesn't mean we should become fat-phobic, as dietary fat is important to provide essential fatty acids and the fat-soluble vitamins: A, D, E and K. In particular, omega-3 fatty acids have been shown to be beneficial for health. One of the best sources is oily fish, and although there are some alternative plant sources - rapeseed oil, pumpkin seeds and walnuts - it may be necessary to consider a dietary supplement where intakes are not adequate.
In theory, a varied and wholesome nutrient-rich diet that includes at least five portions of fruit and vegetables a day should provide an adequate supply of vitamins and minerals for good health (see Table 2). However, in some circumstances where food intake or food choices are restricted, such as vegetarianism, travelling or perhaps restricting energy for weight loss, then a multivitamin and mineral supplement, particularly one that's been designed with active lifestyles in mind, may be useful. There is also a growing body of evidence that suggests dietary antioxidants may be particularly beneficial to help combat environmental stress when exercising outdoors in urban areas.

[[NIP18_table2_63]]

The enormous health benefits of exercise far outweigh feeling a bit lightheaded, but people will still be much more likely to enjoy being physically active and, therefore, keep being active if they feel more comfortable. So, advise people to eat plenty of carbohydrates, including those little energy snacks, before and after exercise - they'll fuel activities and enable them to reap the benefits of a healthy active lifestyle.

References
The information in this article is based on the conclusions of the International Olympic Committee (IOC) Consensus Conference on Sports Nutrition 2003.  More information can be found in the references below and in the British Olympic Association (BOA) sports nutrition book Fuelling Fitness for Sports Performance by Dr Samantha Stear, available directly from the BOA via the website www.teamgbolympicstore.com
The full manuscripts from the Consensus Conference have been published in a Special Issue of the Journal of Sports Sciences, January 2004 (ISSN: 2064-0414):
Burke LM, Kiens B, Ivy JL. Carbohydrates and fat for training and recovery. J Sports Sci 2004;22:15-30.
Coyle EF. Fluid and fuel intake during exercise. J Sports Sci 2004;22:39-55.
Shirreffs SM, Armstrong LE, Cheuvront SN. Fluid and electrolyte needs for preparation and recovery from training and competition.
J Sports Sci 2004;22:57-63.
Tipton KD, Wolfe RR. Protein and amino acids for athletes. J Sports Sci 2004;22: 65-79.
Maughan RJ, King DS, Lea T.
Dietary supplements. J Sports Sci
2004;22:95-113.