Lipids (Fats)

Lipids come in three main forms:
1. Triglycerides (food & storage format)
2. Phospholipids
3. Sterols

Fatty Acids are always defined by the degree of saturation, where more hydrogen bonds indicated a higher level of saturation. The higher the degree of saturated, the harder the fat is and the less healthy that fat is in the body and the higher the risk for heart disease. We called these unhealthy fats, saturated fats and then healthier fats with less hydrogen bonds, unsaturated fats. Unsaturated fats can either be monounsaturated or polyunsaturated. A polyunsaturated fat is an essential fatty acid that cannot be made in the body but is essential for optimal health and functioning in the body.

Functions of Lipids

Lipids have many functions in the body, below are a few:

• Cell membrane structure & functioning
• Precursor to hormones
• Cellular signals between cells
• Regulation of nutrients in the cells
• Surrounding, protecting and holding in place organs (heart, kidney and liver)
• Insulation
• Prolonging the digestive process by decreased HCl secretion therefore increased satiety
• Initiating the release of CCK which contributes to satiety
• Assist in the absorption and storage of fat soluble vitamins, A, D, E and K.

Digestion & Absorption of Lipids

Digestion of fats starts in the mouth and then via the release of bile by the gall bladder, shortly after the duodenum this allows for the emulsification of fats (where fats are broken down into their smallest component). They are then absorbed into blood, reassembled as triglycerides and released into the blood stream as a chylomicron and then via an enzyme called lipoprotein lipase this energy is released into a cell.

Dietary requirements

Fresh butter

The dietary requirements of lipids or fats in the diet should be around 20 – 35% of Total Energy with athletes having slightly higher requirements, around 20 – 25% of total energy. Many people attempt to follow a fat free diet, but there has been no proven benefit to consuming >15% of fats in the diet; remembering often that fat free products are often very high in sugars.

Lipid Properties & Review

  • One gram carbohydrate provides 39kJ (9kcal).
  • Body requires Fats for

o Energy
o Cell structure and membrane function
o Precursor to membranes
o Cellular Signals
o Regulation of uptake & excretion of nutrients to cells

  • Intake Recommendations

o 20-35% of Total Energy
o 20 – 25% of Total Energy for athletes
o The ratio of polyunsaturated fats must be higher to saturated fats