Chapter 15a

1. Chapter 15a Nutrition and Weight Control Lecture Presentation Betty McGuireCornell University

2. Nutrition and Weight Control • Planning a healthy diet • Nutrients • Food labels • Energy balance • Obesity • Weight-loss programs • Eating disorders

3. Planning a Healthy Diet • MyPyramid • Food guide released by the U.S. Department of Agriculture (USDA) to help plan a well-balanced diet • Personalized • 12 different pyramids based on age, gender, level of activity

5. Planning a Healthy Diet • A healthy lifestyle includes • Choosing foods wisely • Staying within your calorie needs • Engaging in physical activity

6. Nutrients • Food provides • Fuel for cellular activities • Building blocks for • Cell division • Maintenance • Repair • Molecules, such as vitamins, needed to coordinate body processes • Water for cellular reactions and the proper cellular environment

7. Nutrients • A nutrient is a substance in food that • Provides energy • Becomes part of a structure • Performs a function in growth, maintenance, or repair

8. Nutrients • Lipids • Fats • Oils • Cholesterol • 95% of the lipids found in food are triglycerides • Consist of three fatty acids attached to a glycerol

9. Nutrients • Fatty acids differ in their degree of saturation • Saturation = extent to which each carbon in the fatty acid is bonded to as many hydrogen atoms as possible

10. Nutrients • Saturated fat • Contains all the hydrogen atoms it can hold • Solid at room temperature • Most comes from animal sources

11. Nutrients • Unsaturated fats • Polyunsaturated • Can hold four or more additional hydrogen atoms • Monounsaturated • Can hold two or more additional hydrogen atoms • Liquid at room temperature (e.g., oils) • Come from plant sources

12. Nutrients • Functions of fat • Ready source of energy • Insulation • Cushion for vital organs • Components of cell membranes • Construction of myelin sheaths • Absorption of fat-soluble vitamins (A, D, E, and K) • Cholesterol is the structural basis for steroid hormones

13. Nutrients • A high-fat diet is associated with • Obesity • High blood pressure • Atherosclerosis • Increased risk of type 2 diabetes • Certain cancers • Colon, prostate, lung

14. Nutrients • Low-density lipoproteins (LDLs) • Bad form of cholesterol • Deposit cholesterol in the artery walls • High-density lipoproteins (HDLs) • Good form of cholesterol • Carry cholesterol from cells (and possibly artery walls) to the liver for elimination

15. Nutrients • Indicator of risk: • Ratio of total cholesterol to HDLs should not exceed 4:1

16. Nutrients • Dietary fats • Saturated fats • Found in meat, butter, cheese, whole milk • Boost harmful LDLs • Trans fats • Formed when hydrogen atoms are added to unsaturated fats (oils) to stabilize or solidify them • Found in packaged foods • Boost harmful LDLs and lower good HDLs

17. Nutrients • Dietary fats (cont.) • Monounsaturated fats • Found in oils (olive, canola, peanut) and nuts • Lower total blood cholesterol and LDLs • Polyunsaturated fats • Lower total blood cholesterol and LDLs

19. Nutrients • Carbohydrates • Simple carbohydrates • Monosaccharides and disaccharides • Include refined sugars • Provide energy but have no other nutritive value “empty calories” • Complex carbohydrates • Polysaccharides • Include starches and fiber • Provide energy and other nutrients

21. Nutrients • Dietary fiber • Found in all plants eaten for food • Humans cannot digest • Benefits • Good for the heart and blood vessels • Lowers LDLs but does not lower the beneficial HDLs • Good for digestive health • Absorbs water, making stools easier to pass

22. Nutrients • Glycemic response • A measure of how quickly a serving of food is converted to blood sugar (glucose) • Glycemic index • A numerical ranking of carbohydrates based on their glycemic response • Ranges from 0 to 100 • Foods with a low value cause a modest, gradual increase in blood sugar and are recommended

23. Nutrients • Proteins • Chains of amino acids that are digested and delivered to the cells • Human proteins contain 20 different kinds of amino acids • 11 amino acids can be made by the body • 9 must be supplied by the diet = essential amino acids

24. Nutrients • Proteins (cont.) • Types • Complete • Contain ample amounts of all the essential amino acids • Most animal proteins • Incomplete • Low in one or more of the essential amino acids • Most plant proteins

26. Nutrients • Complementary proteins • Combinations of incomplete proteins from two or more plant sources that together supply ample amounts of all the essential amino acids • Important in vegetarian diets

28. Nutrients • Vitamins • Organic (carbon-containing) compounds that are needed in minute quantities • Usually function as coenzymes

29. Nutrients • Vitamins (cont.) • Categories • Water-soluble • C and various B vitamins • Fat-soluble • A, D, E, and K • Except for vitamin D, our cells cannot make vitamins, so we must obtain them from food

30. Nutrients • Minerals • Inorganic substances essential to many life processes • Examples include calcium, phosphorus, potassium, sodium, and chloride

31. Nutrients • Water • Perhaps the most important nutrient • Functions • Transports material through our bodies (in blood and lymph) • Provides a medium for chemical reactions • Lubricates and cushions organs • Helps regulate body temperature (sweat)

32. Nutrients | Diet Meals PLAY

33. Food Labels • Using the information on food labels can help you make healthy choices • Examine • Serving size • Calories • % Daily values

35. Energy Balance • The body requires energy for • Maintenance of basic body functions • Physical activity • Processing food that is eaten

36. Energy Balance • Basal metabolic rate (BMR) • Energy needed strictly for maintenance • Generally represents 60–75% of the body’s energy needs • Declines with age

37. Energy Balance • Physical activity • Dietary Guide for Americans recommends 30 minutes of moderate activity on most days of the week • Aerobic exercise reduces risk of heart disease and lowers blood pressure • Weight-bearing exercise reduces risk of osteoporosis • Regular physical activity reduces stress and risk of many chronic diseases

38. Obesity • Body Mass Index (BMI) • Evaluates your weight in relation to your height • Provides a reliable indicator of body fat • BMI > 30 is generally considered unhealthy and an indication of obesity

41. Obesity • Health risks associated with obesity • Disease of the heart and blood vessels • Raises total cholesterol levels and lowers beneficial HDLs • High blood pressure • Type 2 diabetes • Gallstones • Degenerative joint diseases

42. Obesity | Gastric Bypass Surgery PLAY

43. Weight-Loss Programs • Successful weight-loss programs usually include • Reduction in the number of calories consumed • Increase in energy expenditure • Behavior modification

44. Weight-Loss Programs • The number of calories required daily depends on • Activity level • Age • Recommended ways to reduce calories • Reduce fatty foods • Avoid sugars • Increase fiber (filling)

45. Weight-Loss Programs | Fast Food Diets PLAY

46. Eating Disorders • Weight loss can be dangerous • Anorexia nervosa • Deliberate self-starvation • Body weight 85% or less than expected for height • Bulimia • Binge eating large amounts of food, following by purging • Serious eating disorders can be fatal

48. Eating Disorders • Negative effects of anorexia nervosa • Poor bone health • Breakdown of proteins for energy • Reduction in mass of skeletal and heart muscle • Dehydration • Electrolyte imbalance

49. Eating Disorders • Negative effects of bulimia • Esophageal injuries • Tooth decay • Gum disease • Dehydration • Constipation • Electrolyte imbalance