Running for Fitness

One of the pleasures of being a runner is that you can eat and drink considerably more than if you have a sedentary lifestyle, and still feel healthy and avoid putting on weight.

Running enables you to escape from the constant hunger, self-denial and self-loathing of dieting, and instead enables you to eat a wide variety of foods more or less as you please.

Nutrition is the third most important determinant of your running performance, after genetics and training.  If you want to be a good runner, you have to eat and drink the right things.  This chapter is about the food and drink you need to maintain a healthy body; the next chapter is about how you should eat and drink before, during and after running.

The main rule for a balanced diet for a typical healthy adult is to eat from a wide range of unprocessed foods.  If you do this, you will not go far wrong. There are several good books about nutrition for athletes which you should read if you want more detail, or if you have special needs (for example, if you are vegetarian or allergic to particular foods). [i] This chapter introduces the key principles for runners.

The main nutrients

The main nutrients for human beings are carbohydrates, fats, protein and water.

Carbohydrates

Carbohydrates are mainly used for energy. Foods that are high in carbohydrate include potatoes, pasta, rice, bread, fruit, cereals, pulses and anything sugary.

Carbohydrates vary in the complexity of their chemical structure, which in turn affects how quickly they are absorbed into your bloodstream.  Scientists have developed the Glycaemic Index (GI) which ranks foods according to their immediate effect on blood sugar levels. For example, apples have a GI of 38, which means that eating an apple gives you about 38% of the increase in blood sugar that you would get from eating pure glucose.

Table 6.1 High, medium & low glycaemic index foods

High GI foods		Moderate GI foods		Low GI foods
Food	GI	Food	GI	Food	GI
Glucose	100	All bran	42	Chick peas	33
Cornflakes	84	Muesli	56	Green lentils	30
Weetabix	69	Buckwheat	54	Red lentils	26
Brown rice	76	Basmati rice	58	Soya beans	18
White rice	87	Spaghetti	41	Kidney beans	27
Bagel	72	Muffin	44	Apples	38
Baguette	95	Carrots	49	Pears	38
Parsnip	97	Peas	48	Plums	39
Baked potato	85	Baked beans	48	Peanuts	14
Raisins	64	Banana	55	Milk	27
Mars bar	68	Orange	44	Yoghurt	33

The glycaemic index was originally developed to help diabetics to manage their blood sugar, but it is becoming more widely recognised as a tool for healthy eating.  You will need to look at the GI of the meal as a whole (which you can estimate by a weighted average of the GI of the main components).

Generally, you should eat low-GI meals, because these don’t lead to such large variations in your blood sugar and insulin levels. Big swings in your blood sugar can lead to higher levels of body fat, reduced immunity from infection, mood swings and stress, and impaired storage of energy by muscles.

However, high GI foods are very useful when need energy quickly, such as immediately before, during and after exercise (see Chapter 7).

Fats

Fats are found in oily food, especially animal products, and food cooked in oils.   Fats vary in their chemical structure, which in turn makes a difference to how they are handled by the human body and their impact on health.  Some fats are harmful, and some are essential for health.

Table 6.2 Types of fat and their health implications

Type of fat	Health implications	Sources
Saturated	Heart disease, increase in cholesterol.	Butter, lard, cheese, animal fats.  Biscuits, cakes, pastry.  Palm oil & coconut oil
Monounsaturated	Good for you.  Can reduce harmful cholesterol.	Olive, rapeseed, groundnut, hazelnut, almond oils. Avocados, olives, nuts, seeds.
Polyunsaturated	Can reduce both good and harmful cholesterol.	Most vegetable oils and oily fish.
The following fatty acids are specific types of polyunsaturated fat:
Omega 3 essential fatty acids	Health of blood and blood vessels. Reduced heart disease, lower blood pressure.	Oily fish (e.g. mackerel, fresh tuna, salmon, sardines).  Linseed (flax), pumpkin seeds, walnuts, rapeseed oil, soyabeans.
Omega 6 essential fatty acids	Health of cell membranes. (But can reduce good cholesterol; high intake may be cancer risk)	Vegetable oils, polyunsaturated margarine.

In general, many people in western societies eat more fat than they should; and too much of it is harmful saturated fats. You should be getting around 15-25% of your daily calories from fat, instead of an average of over 40% in Britain.  But you should not try to cut fats out of your diet altogether.  Try to get most of your fats from mono-unsaturated fats, such as olive oil, nuts and avocados; and ensure that you have sufficient essential fatty acids, which you get from oily fish and seeds.

Protein

Proteins are the building blocks of the human body.  About 20% of your body weight is protein.  It is mainly needed for growth and repair of body tissues, though it can also be used as fuel for energy.  It also plays an important role in the health of your blood system.

The protein you eat is broken down into amino acids, and then recombined to make suitable human proteins.  There are 20 amino acids, of which 12 can be manufactured in the body; but 8 of them, called essential amino acids, cannot, and they must be obtained from what you eat.

Some foods contain all eight essential amino acids – these include dairy products, eggs, meat, fish, and soya.  Other foods such as cereals, pulses and nuts have some, but not all, of the essential amino acids and must be eaten in the right combinations to ensure the body has all the components it needs.  Vegetarians, and anyone else who does not eat much meat, should ensure that they combine foods from two or more of the following four categories:

• pulses (beans, lentils, peas)
• grains (bread, pasta, rice, cereals, corn, rye)
• nuts and seeds (peanuts, sunflower seeds, pumpkin seeds)
• quorn, tofu and soya products (soya milk, tofu, tempeh, etc)

For example, baked beans on toast is an excellent combination which provides all the essential amino acids.

If you exercise regularly, and especially if you do strength training, you need a bit more protein than if you are sedentary, to enable you to rebuild and repair muscles.    The current recommended daily intake of protein for a sedentary person is 0.75g of protein a day for every kilogram of body weight; whereas people who exercise need around twice this (1.25g to 1.75g) amount of protein a day for every kilogram of body weight.[ii]

Table 6.3: Protein intake

Lifestyle	Grammes Per day per kg	Example for 60kg person	Example for 80kg person
Sedentary	0.75	45g / day	60g / day
Endurance runner	1.3	78g / day	104g / day
Strength athlete	1.6	96g / day	128g / day

You can safely eat more protein than this calculation implies, but once your body has used the protein it needs, the extra protein will be burned as energy.  (It is a common myth that eating more protein than this will somehow stimulate better or more muscle formation.)

Eating a balanced diet

Your energy intake should come from a mixture of carbohydrates, fats and protein, made up roughly as follows:

• 15-25% of calories from fat
• 60-70% of calories from carbohydrates
• 15-25% of calories from protein.

From these broad proportions, an estimate of your overall energy needs (see below) and the amount of protein you need, you can estimate the amount of carbohydrate, fat and protein you should have in your diet.

You can do this calculation for your own body weight and calorie intake here on the Running for Fitness website.

However, you should beware of the fact that the different types of food provide different amounts of energy for each gram:

Table 6.4 Energy from different nutrients

Energy source	Energy (kcal)	Energy (kJ)
1g of carbohydrate	4 kcal	17 kJ
1g of fat	9 kcal	38 kJ
1g of protein	4 kcal	17 kJ
1g of alcohol	7 kcal	29 kJ

Because fat has more than twice as many calories per gram as carbohydrates and protein, you should eat a lower proportion of fat by weight of food than the proportion of fat measured by calories provided.  So if fat is 20% of your diet by calories, it should only be 10% of your diet by weight.

Table 6.5 Sample breakdown of carbohydrate, fat and protein

Nutrient	2500 Kilocalories a day		3500 Kilocalories a day
	Calories	Grams	Calories	Grams
Carbohydrate	1500 kcal 60 %	375g 68%	2100 kcal 60%	525g 68%
Fat	500 kcal 20%	56g 10%	700 kcal 20%	78g 10%
Protein	500 kcal 20%	125g 22%	700 kcal 20%	175g 22%

Within this basic structure of your nutrient intake, try to eat at least five portions of fruit and vegetables a day (a portion is about 80g – equivalent to an apple or two tomatoes).

Later in this chapter, we shall look at the way you can adjust this calculation if you want to lose weight.

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[i] For example The Complete Guide to Sports Nutrition, by Anita Bean (A&C Black).

[ii] Williams, C. and Devlin, J.T. (eds) Food, Nutrition and Performance: An International Scientific Consensus, 1992. Chapman & Hall.