TABLE OF CONTENTS Fats or lipids are the second important source of energy in the diet. The term lipid includes both fats and oils the former being solid and the latter liquid at room temperature. On a weight-for-weight basis they yield over twice as much energy as carbohydrates. There are many different types of lipid, and they are utilised in many different ways by the body contributing to cell, tissue and organ structures, as well as being a major energy provider. Although they have a poor reputation in terms of the diet, they come in many different forms and they are an essential part of the diet.
Their diversity of roles in the body is their main dietary difference from carbohydrates, which are primarily used as an energy source. In certain cases, the body cannot make individual lipids itself and is totally reliant on a dietary source.
The bulk of the lipids that we consume and the major energy-providing forms are the triglycerides. These consist of two components: glycerol joined (esterified) to three fatty acids long-chain molecules with acid ( carboxyl ) end-groups. These two components can become separated in food (hydrolysed). If this happens in the food it can result in the formation of off-flavours (hydrolytic rancidity). This hydrolysis itself is of no dietary significance, as it is the first thing that the body does with triglycerides.
The different chain lengths (i.e. number of carbon atoms), and the number and position of double bonds along the chain mean that there...
