Fats are hydrolysed into fatty acids and glycerol during digestion which is then converted into pyruvate which can be decarboxylated to produce an acetyl group which is combined with coenzyme A and can then enter the Krebs cycle. Fatty acids are also converted into acetyl coenzyme A. Proteins need to be converted into amino acids which undergo deamination in the liver, with the resulting molecule then being converted into pyruvate which enters the link reaction. Because energy is required, protein gives a lower yield of ATP than carbohydrates
