Copyright © 2012 Pearson Education, Inc. Chapter 15a Nutrition and Weight Control Betty McGuire Cornell University Lecture Presentation

Copyright © 2012 Pearson Education, Inc. Nutrition and Weight Control  Planning a healthy diet  Nutrients  Food labels  Energy balance  Obesity  Weight-loss programs  Eating disorders

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc.

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

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc. Nutrients  A nutrient is a substance in food that  Provides energy  Becomes part of a structure  Performs a function in growth, maintenance, or repair

Copyright © 2012 Pearson Education, Inc. Nutrients  Lipids  Fats  Oils  Cholesterol  95% of the lipids found in food are triglycerides  Consist of three fatty acids attached to a glycerol

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc. Nutrients  Saturated fat  Contains all the hydrogen atoms it can hold  Solid at room temperature  Most comes from animal sources

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc. Nutrients  A high-fat diet is associated with  Obesity  High blood pressure  Atherosclerosis  Increased risk of type 2 diabetes  Certain cancers  Colon, prostate, lung

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc. Nutrients  Indicator of risk:  Ratio of total cholesterol to HDLs should not exceed 4:1

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc.

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

Copyright © 2012 Pearson Education, Inc.

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

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc.

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

Copyright © 2012 Pearson Education, Inc.

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

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc. Nutrients  Minerals  Inorganic substances essential to many life processes  Examples include calcium, phosphorus, potassium, sodium, and chloride

Copyright © 2012 Pearson Education, Inc. 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)

Copyright © 2012 Pearson Education, Inc. Nutrients PLAY | Diet Meals

Copyright © 2012 Pearson Education, Inc. Food Labels  Using the information on food labels can help you make healthy choices  Examine  Serving size  Calories  % Daily values

Copyright © 2012 Pearson Education, Inc.

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

Copyright © 2012 Pearson Education, Inc. Energy Balance  Basal metabolic rate (BMR)  Energy needed strictly for maintenance  Generally represents 60–75% of the body’s energy needs  Declines with age

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc.

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

Copyright © 2012 Pearson Education, Inc. Obesity PLAY | Gastric Bypass Surgery

Copyright © 2012 Pearson Education, Inc. Weight-Loss Programs  Successful weight-loss programs usually include  Reduction in the number of calories consumed  Increase in energy expenditure  Behavior modification

Copyright © 2012 Pearson Education, Inc. 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)

Copyright © 2012 Pearson Education, Inc. Weight-Loss Programs PLAY | Fast Food Diets

Copyright © 2012 Pearson Education, Inc. 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

Copyright © 2012 Pearson Education, Inc.

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

Copyright © 2012 Pearson Education, Inc. Eating Disorders  Negative effects of bulimia  Esophageal injuries  Tooth decay  Gum disease  Dehydration  Constipation  Electrolyte imbalance