Pyramid Science

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Tuesday, December 23, 2008

Nutrition


Nutrition is central to maximal performance. The short term is to reduce body fat and increase muscle mass. Recovery time between training sessions should be quicker so a higher volume of work is possible. In the longer term it is to improve the capacity to resist injury and illness, reduce common 'wear and tear' conditions like arthritis and osteoporosis, cancer and heart disease. Between 20-60 years, the aging effects are minimal if well nourished. Mostly, any decline is due to reduced activity, poor nutrition and stress.

Lean muscle tissue is hard and made of protein in origin. Consuming more protein cannot build more muscle. In terms of evolution there are three main threats to survival:
  • Starvation
  • Freezing
  • Predators
The production and regulation of energy has priority, metabolically speaking. No energy means no ability to drive the biochemical reactions that sustain life. In periods of starvation, the body firstly consumes fat then protein before itself (internal organs). Muscle mass and strength are not useful against cold conditions. Protein metabolism is intimately connected with energy metabolism.

To gain strength from muscle mass, the requirements for body must firstly be provided. Nutrition must be seen as an addition to strength training, not weight training by itself. Muscle has its constituents from protein from amino acids. Of the 20 in the human body, 8 must come from the diet as essential amino acids since the body cannot synthesise them.
Protein metabolism is closely linked to the biochemical energy-producing cycles.

Citric Acid Cycle

The Kreb Citric Acid Cycle generates adenosine triphosphate (ATP) from partially degraded carbohydrates, fats and proteins and is dependent on conditions. When carbohydrate is in short supply, the body will use proteins and fats. It is now known that proteins, or more exactly the amino acids from which they are constructed, provide a significant source of energy during periods of intense energy production: aerobic vs anaerobic exercise In particular the branched chain amino acids (Valine, Leucine and Isoleucine). Not just carbohydrates or fats. Muscle proteins are rich in these branched chain amino acids so can be utilised in intense activity: anaerobic weight training. They are easily broken down (oxidised) and once the branched chain amino acids have been used the rest of the protein is rendered useless. The amino acids then go back into the amino acid pool or provide energy, but are lost to the system. It is obvious that the energy requirements must be satisfied, but paradoxically intense training has the opposite of the desired effect.

High Grade Fuel

Carbohydrates (carbs) then fat or protein is the order of ease of oxidation. Ideally, these carbs should be of complex variety: whole grains, pulses, vegetables and fruit. This ensures a sustained and gradual release of sugars (low glycemic index). Muscle glycogen is maintained more efficiently and the need for protein oxidation is reduced. High glucose levels in blood assist transport of amino acids to muscle cells. Complex sugars (starches) provide a more stable and constant supply of blood glucose. Carbs and proteins are required together. Protein level of about 0.75g/kg is a probable minimum protein per day (World Health Organisation), but up to 2g/kg for heavy workloads according to research by the US National Research Council. Yet excess protein cannot be stored directly (deamination transforms the protein into carbon and hydrogen products by removal of the amino group as ammonia). This places an extra burden on the liver, so there is no advantage to be gained by consuming too much protein.

For most athletes between 1-1.5g/kg sufficient allowing the total calorie needs to be made upfrom carbs and fat. Most complex carbs contain around 10% protein so a high carb diet such as this could provide the protein requirements. A transaminase is an enzyme which interconverts amino acids. Excess amino acids from new and old protein matter can provide non-essential amino acids by transaminase. This requires zinc and vitamin B6 for activation. Zinc is also required for the action of the enzyme carboxypeptidase and is crucial for digestion of dietary proteins to amino acids. This is then used in the synthesis of muscle tissue. Vitamin B6 is required for absorption of amino acids across the intestine wall and into the bloodstream. Diets low in these essential nutrients lead to less efficient protein metabolism. A low level of nutrients prevents the efficient utilisation of proteins from the diet and results in a failure to build muscle tissue.

Chromium Requirements

Around 100mcgm daily appears to be crucial in the correct functioning of the insulin system and a chromium is a critical component of the Glucose Tolerance Factor (GTF). This enhances the activity of insulin in the body and it is insulin which promotes transport of glucose to muscle cells. An amino acid is taken into cell with a glucose molecule, so the importance of chromium is obvious: chromium is crucial in the metabolism of carbohydrate. An increase in chromium (as picolinate) produces lean body mass increases of 44% greater compared to athletes on standard intakes. These gains are accompanied by increased rates of fat loss. Other human studies have had only limited success in reproducing these results, although animal studies have consistently shown the same effect and it appears that extra chromium in poor diets can be of real benefit, but in a good diet this may be of limited benefit. Refined grains and sugars in modern diets may be low in chromium so supplementation should be considered. Low chromium also shown to increase blood cholesterol and circulating blood lipids with the consequent greater risk of cardiovascular disease.

Timing

After training, there is a one to four hour window to intake protein for absorption of amino acids and to repair and build muscle after strenuous training. Later than this and the propensity of muscle to absorb nutrients falls away and is eventually lost all together. Trained and untrained muscle are not different in this respect. Genetics play an important r├┤le in growth. Thinner and more wiry builds tend to have a faster metabolic rate and consequent higher energy requirements. There is a greater need for carbs. If slim there is a need for high carbs AND adequate protein. Eat frequent, small meals without too much aerobic exercise. Muscle will be catabolised. Fast gainers often carry a slightly higher level of body fat so adequate protein is matched by a lesser intake of carbs. The shortfall in the total calorie count is made up from fats. So wiry people need a greater carb:protein ratio (more protein) than do stockier builds (more carbs).

The benefits of creatine as a sports supplement are still unclear. Creatine should be regarded as the last addition to nutrition after everything else has been fixed if for no other reason than cost. It's expensive and the effects are questionable.

Reducing Body Fat

There are no shortcuts. There is no magic. A proper mixture is a diet consisting of unprocessed, natural and whole foods with regular (aerobic) exercise. Efficient mechanisms for storing energy in times of abundance evolved for use during those times of scarcity.

Storage of body fat

Fat is a very concentrated form of energy for its weight (muscle glycogen has around 75%. of its weight as water). It is also a good insulator against cold. These efficient pathways evolved against a background of the reverse situation and calories are burnt off to provide energy. Storage is easier than removing and so to reduce body fat the storage pathways should be stimulated as little as possible and the oxidation pathway to burn stored fat is stimulated as much as possible This last point arises from fact that carbs, not fat, are the preferred source of energy. Encouraging the body to use fat as a source is not easy and it can be seen why obesity is so prevalent. The abundance of nutritionally poor foods mixed with a lifestyle of inactivity. Calorie counting does not work and 'eating fewer calories' still results in the prevalence of obesity. Calories all carry the same chemical energy whether they originate from fat, carb or protein. Calories are not eaten, but they do result from food, but they do interact differently with the metabolism. Calories from some foods can be converted to stored body fat more easily than others.

The route back from stored fat is difficult. The enzyme is present in the human body to convert carbohydrate into fat, but the reverse process is not possible. The enzyme for that purpose is not present. The metabolism runs faster earlier in the day and a substantial breakfast is ideal. A decent lunch is beneficial, but a small evening meal should be consumed. Eating early actually increases the basal metabolic rate and evens out peaks and troughs in energy. Several small and frequent meals are better than one or two large ones and reduces the likelihood of excess calories being dumped as fat. Any excess fat is stored directly as body fat without biochemical transformation. So keep the actual fat intake low, <30% of total. However, some fat is essential for good health. Fatty acids in nuts, seeds, oily fish. This highlights the range of fats that are available. Animal fat (lard) is not the same as the fat from an avocado pear. A well nourished body can maintain lower levels of body fat when the diet contains some fat. It is important to realise that some biochemical reactions take place in a fatty medium and not water.

Calories from different types of carbohydrate have a different fate in the body. Refined sugar has a high glycemic index. Glucose = 100 and the speed of release into bloodstream is measured by the glycemic index. The faster the rate the more the insulin that is released, leading to fat storage (of the excess unburnt calories).

  • Cereals
    • cornflakes = 80
    • weetabix = 75
    • shredded wheat = 67
    • porridge oats = 49
    • fruit raisins = 64
    • bananas = 62
    • oranges = 40
    • apples = 39
  • Grain Products
    • white rice = 72
    • wholemeal bread = 72
    • brown rice = 66
    • oatcakes = 54
    • white pasta = 50
    • wholemeal pasta = 42
  • Sugars
    • glucose = 100
    • lucozade = 95
    • honey = 87
    • fructose = 59
  • Pulses
    • baked beans = 40 (no sugar)
    • butter beans = 36
    • chick peas = 36
    • kidney beans = 29
    • lentils = 29
    • soya beans = 15
Once fat is stored it is hard to get rid of. Refined carbs can also lead to poor glucose tolerance and this results in energy swings and sugar cravings. Complex and unrefined whole grain carbs have lower glycemic indeces, releasing calories gradually avoiding the insulin high. Additionally, a higher level of nutrients (some are crucial to fat metabolism) are present unlike the refined foods. Aerobic work enhances the oxygen-carrying capacity of the body and this increases the rate at which oxygen is delivered to the cells (see also mitochondria). Oxidation of fat requires an oxygen rich environment, which is encouraged by aerobic exercise.

Basal metabolism will be reduced if muscle mass is lost and is a common effect of crash diets. Chromium regulates of the blood sugar level and carbohydrate metabolism. How chromium works is unclear, but it is certainly implicated. Whole unprocessed grains are low in refined grains and should be part of a staple diet. Other fat metabolising components are vitamin B1, B2, B3, B5 and the minerals magnesium and manganese. A modest amount of calories taken as fat, but used in lower impact aerobic work, should result in an optimal loss of around 2 pounds/month. Fat is needed to lose fat.

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