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Chapter 15a. Nutrition and Weight Control. Lecture Presentation. Betty McGuire Cornell University. Nutrition and Weight Control. Planning a healthy diet Nutrients Food labels Energy balance Obesity Weight-loss programs Eating disorders. Planning a Healthy Diet. MyPyramid - PowerPoint PPT Presentation
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Copyright © 2012 Pearson Education, Inc.
Chapter 15aNutrition and
Weight Control
Betty McGuireCornell 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
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Planning a Healthy Diet
A healthy lifestyle includes Choosing foods wisely Staying within your calorie needs Engaging in physical activity
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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
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Nutrients
A nutrient is a substance in food that Provides energy Becomes part of a structure Performs a function in growth, maintenance,
or repair
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Nutrients
Lipids Fats Oils Cholesterol
95% of the lipids found in food are triglycerides Consist of three fatty acids attached
to a glycerol
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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
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Nutrients
Saturated fat Contains all the hydrogen atoms it can hold Solid at room temperature Most comes from animal sources
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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
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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
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Nutrients
A high-fat diet is associated with Obesity High blood pressure Atherosclerosis Increased risk of type 2 diabetes Certain cancers
Colon, prostate, lung
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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
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Nutrients
Indicator of risk: Ratio of total cholesterol to HDLs should not
exceed 4:1
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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
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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
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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
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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
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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
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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
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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
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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
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Nutrients
Vitamins Organic (carbon-containing) compounds that
are needed in minute quantities Usually function as coenzymes
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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
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Nutrients
Minerals Inorganic substances essential to many life
processes Examples include calcium, phosphorus,
potassium, sodium, and chloride
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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)
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Food Labels
Using the information on food labels can help you make healthy choices
Examine Serving size Calories % Daily values
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Energy Balance
The body requires energy for Maintenance of basic body functions Physical activity Processing food that is eaten
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Energy Balance
Basal metabolic rate (BMR) Energy needed strictly for maintenance Generally represents 60–75% of the body’s
energy needs Declines with age
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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
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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
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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
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Weight-Loss Programs
Successful weight-loss programs usually include Reduction in the number of calories
consumed Increase in energy expenditure Behavior modification
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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)
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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
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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