Balanced Diet

Balanced diet should include macronutrients; micronutrients; water and fibre or Balanced diet should include fats; carbohydrates; proteins; vitamins; minerals; water; fibre

OR

Correct proportions of macronutrients and micronutrients.

The exam board recommends:

55% carbohydrates, 30% fat, 15% proteins

The macronutrients are carbohydrates, fats (sometimes called lipids)and proteins. They are food components that should be eaten in large quantities that are needed because they contain energy that we can use to maintain bodily function.

See Energy for more information on Carbohydrates and Fats

Carbohydrates (CHO)

Carbohydrates provide a major source of energy to the body. At rest between 20 and 30% of our energy needs are provided by the breakdown of this fuel, however during high intensity this may increase to over 90%. A lack of carbohydrate in the diet can lead to tiredness and fatigue and poor mental function. Immune system function is dependant on carbohydrate so a lack of this macronutrient in the diet can lead to more frequent colds, respiratory illnesses and other conditions. In athletes ‘over-training’ can occur more readily if CHO requirements are not met. For every gram of carbohydrate approximately 4 kcal of energy can be produced.

Carbohydrates can be broken down into three classifications; monosaccharides, disaccharides and polysaccharides.

• Monosaccharides are single molecules and are therefore the smallest type of carbohydrate (often called Simple Carbohydrates) . Glucose, fructose and galactose are examples of monosaccharides that we find in foods. Glucose is the most commonly known monosaccharide as it is a major fuel during exercise.
• Disaccharides are two monosaccharides joined together (often called Simple Carbohydrates). For example sucrose (sugar) is formed by a glucose and a fructose molecule joined together and lactose (found in milk) is a combination of a glucose and a galactose molecule.
• Polysaccharides are when three or more monosaccharides are joined together (often called Complex Carbohydrates). The most common polysaccharides are;

Cellulose is a combination of thousands of glucose molecules and is the structural component of the cell wall in green plants. Humans’ digestive systems do not contain enzymes that can breakdown cellulose so this is one of the food constituents that make up our dietary fibre.

Starch is the plants storage form of carbohydrate. It is composed of many glucose molecules, but unlike cellulose the bonds between them can be easily broken down so enzymes can do this in the stomach and small intestine. Most of the carbohydrate we get from a diets comes from the starch contained in breads, rice, potatoes, fruits and other foods high in carbohydrate.

Glycogen is a combination of many glucose molecules. Glycogen is found in the meats and fishes that we eat and is the major form of carbohydrate that we store in our bodies. When glucose passes into the blood from the digestive system (following a meal) it is stored in the muscles and the liver.

There are different types of fats; ‘good’ and ‘bad’ fats. Some fats are essential for health and it is important that enough of them are consumed, whereas others can be harmful to health so their consumption should be limited.

The link between whether fats are beneficial or harmful depends on their impact on the amount of cholesterol and other fats in the body. Having some cholesterol in the body is essential as it is needed for cell membrane production and other functions. Cholesterol cannot dissolve in water so it must be transported around the body by carriers called ‘lipoproteins’. There are two types of lipoproteins that carry cholesterol; low density (LDL) and high density lipoproteins (HDL).

Too much LDL cholesterol is detrimental to health and is a major risk factor for heart disease and strokes, as the arteries can narrow due to plaques forming in them. Having high levels of HDL cholesterol is beneficial to health and can prevent heart disease.

Proteins

Proteins are molecules made up of a number of ‘building blocks’ called amino acids. Amino acids are made up of carbon, hydrogen, oxygen and nitrogen atoms. Protein is essential because it is the major constituent in muscle tissue, the heart, the liver and the brain.

It is also needed when there is damage to any of the tissues that are made up of proteins. For example it is crucial that athletes eat enough protein when they have damaged their muscles like when they experience delayed onset muscle soreness (DOMS) or when they experience a strain. Proteins are also found in enzymes, antibodies, hormones and haemoglobin so are needed for many processes in the body. Because of the vital roles in the body, protein is not a preferred fuel for maintaining basal metabolic processes or during exercise, so typically only 5-10% of our energy production comes from protein metabolism. However, during starvation or very long duration exercise (+4 hours) amino acid contribution can increase significantly.

Power and strength trained athletes require more protein in their diet to repair damaged muscles after training and for the growth of new tissue so that muscles are stronger.

Vitamins and minerals are micronutrients and they are essential in small amounts for growth, metabolism and other bodily functions. They are not directly used as a fuel, although many of them are needed for assisting in the chemical processes that occur when fuels are broken down.

Minerals

Minerals are inorganic compounds found in the body that are vital for effective cell functioning. They are essential for muscle contraction, oxygen transport and helps in the exchange of nutrients into and out of the muscle cell.

Mineral deficiencies are rare with the exceptions of iron and calcium. As both of these minerals are important in the role of health and in the performances of those who train or compete regularly, sports performers are more prevalent to deficiencies.

Calcium is the most abundant mineral in the body, making up approximately 1.5 to 2% of our body mass. Over 99% of calcium is found in our bones and teeth meaning it is essential in our diet to keep bones and teeth healthy. In adults, calcium deficiency can also result in weakened bones, which increases fracture risk and this can increase the chances of developing osteoporosis. Calcium is crucial for nerve function and it plays a vital part of muscular contractions.

Milk and diary products are a major source of calcium and it is recommended that three servings are consumed each day.

Iron is a major component of haemoglobin found in the red blood cells and myoglobin which is a muscle cell’s equivalent. Therefore it is essential for oxygen transport to the muscles and storage of oxygen inside of them. Iron is also needed by certain cells of the immune system to fight infections.

A lack of iron in the diet or not absorbing enough iron from the foods that are eaten will often lead to anaemia. In anaemic individuals a reduction in red blood cell production results in poorer oxygen delivery around the body which can lead to feelings of fatigue and lethargy that can severely affect daily living.

Carboloading

Supercompensation of muscle glycogen relates to having higher than normal resting stores of this important fuel. In trained individuals, normal resting muscle glycogen values are approximately 100 to 120 mmol per kilogram of muscle. Carboloading strategies may lead to double the amount of muscle glycogen with values of between 150 to 250 mmol.kg.

One ‘modern’ method of carboloading involves a period of modified exercise and dietary manipulation.

• Approximately 7 days prior to a competition, an athlete will perform an exhaustive period of exercise.
• For the next 3 days a reduced amount of Carbohydrate will be consumed but this will only drop to about 50% of energy intake.
• For the last 3 days the athlete will revert to a high Carbohydrate diet, getting approximately 70% of energy intake from this macronutrient. This will usually be approximately 8 to 10 grams of carbohydrate for every kilogram of body weight each day. Training intensity and duration (volume) is ‘tapered’ for the full 6 days during this method and this results in similar supercompensation ready for the competition.

Maintaining moderate Carbohydrate intake for the first 3 days of the protocol will mean there is not the greater risk of illness and reduces the chances of feeling severely fatigued, as seen in the classic methods.

Protein supplements

Protein is needed so amino acids can be provided to repair damaged muscles and grow new protein filaments if there has been sufficient overload. Adding protein to meals post-exercise has been shown to improve recovery in a number of research studies. It is recommended that between 10 and 15 grams of protein are consumed in the first 30 minutes following exercise.

Protein shakes and powders are regularly consumed by body builders and others wanting to increase their muscle mass. Despite there being some benefits for some people using these, most expert sports nutritionists agree that protein needs can be easily met by consuming everyday foods. However, there may be times when a protein supplement may be convenient, especially after ‘away’ fixtures or when food will not be available immediately after a training session.

Fibre

Fibre is the component of foods that we cannot digest. The majority of the fibre we eat is in the form of cellulose as we do not have enzymes capable of breaking this down. Fibre is an essential part of our diet because it helps food pass through the digestive system and can prevent; constipation, irritable bowel syndrome and some cancers. Foods containing lots of fibre are also helpful for those wanting to lose body fat because it is another food that helps us to feel fuller so we tend to eat less at other times throughout the day. Adults should eat between 12 and 24 grams of fibre per day, although some researchers recommend more than this.

Water

Approximately 60% of our body weight is water. Although all cells in the body contain some water, it is a major constituent of the brain, blood plasma and muscle cells. For this reason it is essential that we consume enough water. We can survive for a while without food; 4 to 6 weeks is the figure that is usually quoted! However, without water you would be lucky to survive 10 days and in a hot environment you may not even last 48 hours. Water is essential because;

• It is needed for the production of saliva;
• It is an important part of synovial fluid in our joints;
• It helps to moisten the respiratory tract;
• It is needed in the production of urine, to excrete waste products;
• It required to produce sweat which is needed to cool the body when we are hot.

Main food groups: bread, potato, rice, pasta and cereals, meat, fish, pulses, fruits and vegetables, milk and dairy, food and drinks high in fats and sugar.