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Chapter Three: Lipids

Chapter Three: Lipids. Identify the major roles of body fat Identify the 3 classes of body lipids Identify the chemical structure of triglycerides and three ways fatty acids differ from one another

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Chapter Three: Lipids

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  1. Chapter Three: Lipids • Identify the major roles of body fat • Identify the 3 classes of body lipids • Identify the chemical structure of triglycerides and three ways fatty acids differ from one another • Identify food sources of fats, how they differ in saturation, and the dietary recommendations of each type of fat

  2. Lipids contd. • Identify the roles of phospholipids and sterols • Identify the current daily dietary recommendations for fat intake • Identify artificial sources of fat • Explain what a trans-fatty acid is and where it is found

  3. What do you already know? • Lipids (fats) in review • Energy provided: 9 kcals. per gram • No more than 30% of kcals. per day • Sources in the Food Guide Pyramid • Milk, yogurt and cheese group • Meat and meat alternates group • Fats, oils and sweets group

  4. Nutritional Role of Lipids • Main function is for fuel or energy • Supplies about 60% of energy needs • Unlimited storage • Other roles of fats • Nourishment for hair and skin • Insulates and cushions organs & breasts • Major material of cell membranes • Most concentrated form of energy

  5. Forms of Lipids • Triglycerides: Fat storage in the body • Make up of three fatty acids attached to a backbone of glycerol • Makes up 95% of fat in the body and in the diet • Phospholipids: portion of other 5% of lipids found in the body • Found in the cell membrane • Not essential—supplement not necessary

  6. Forms of Lipids contd. • Sterols: portion of other 5% of lipids found in the body • Forms are cholesterol, Vitamin D, and sex hormones • Cholesterol is found in cells and used in metabolism—rec. level is below 200 mg/dl in the blood

  7. Triglycerides

  8. Fatty Acids and Their Saturation Levels • Saturated fats: No more than 10% • Contain all the hydrogen they can hold • Examples are animals fats, palm and coconut oil • Hard at room temperature • Known to increase cholesterol levels

  9. Dietary Fats

  10. Fatty Acids cntd. • Monounsaturated Fats: 10% • One point of saturation is missing • Examples are plant foods such as nuts, avocados, and olive oil • Softer at room temperature • Have a neutral effect on cholesterol levels

  11. Fatty Acids cntd. • Polyunsaturated fats: No more than 10% (PUFAs) • Missing multiple points of saturation • Examples are vegetables oils • Liquid at room temperature • Known to lower cholesterol levels • Sources spoil more easily at room temperature

  12. Fat Substitutes • Carbohydrate based: Oatrim & Z-Trim • Stable when heated • Provides fiber and reduces kcals by ½ • Protein based: Simplesse • Found in dairy products and dressings • Not stable when heated • Reduced kcals. By 80%

  13. Fat Substitutes contd. • Fat-based: Olestra • Indigestible • Stable when heated and tastes like fat • Can cause digestive problems and nutrient losses

  14. Cutting Fat Intake & Choosing Unsaturated Fat Sources • Choose low fat sources • Choose low fat cooking methods • Avoid hydrogenated fats • Avoid fast foods—chips, baked goods and commercially-prepared foods • Trans-fatty acids: formed from the hydrogenation of PUFAs

  15. Test Questions • 1. Which of the following fats is the stored fat in the body and available for energy. • A. Cholesterol • B. Phospholipids • C. Triglycerides • D. Lecithin

  16. Test Questions • 2. The term “unsaturated fat” means that: • A. The fat lacks glycerol • B. Hydrogen ions are missing in the fatty acid chains • C. The carbon chains in the fat are less than ten • D. The fat is hard or solid at room termperature

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