upplied by the respiration of carbohydrates in the cells.
             Carbohydrates are used principally as respiratory substrates. Sources of carbohydrates such as starch are rice, potatoes, wheat, sugar and other cereals. If the diet lacks carbohydrate stores of fat are mobilised and used as an energy source.
             Lipids are a rich source of energy in the diet, they can be greatly reduced in metabolic reactions and therefore release much energy. They are easily stored in the body and can form a layer beneath the skin of adipose tissue. As lipids are such a rich source of energy they are often not needed for respiration if there are adequate quantities of carbohydrate for the energy output of the body. As lipids are digested in the intestine into fatty acids and glycerol, some fatty acids are only available in the diet and cannot therefore be synthesis
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