Prentice6 ppt ch08 (1)

Chapter 8: Limiting Your Body Fat Through Diet and Exercise

McGraw-Hill/Irwin © 2012 McGraw-Hill Companies. All Rights Reserved.

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Why should you be concerned about body fat?

• Fat loss has become a multi-billion dollar industry– While there are numerous ideas and plans,

none can guarantee that the weight will stay off

– Fat lost is often regained

• Most decide to lose weight due to appearance, while others do it for health reasons

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The American Lifestyle

• Food plays a major role in various aspects of our lives– Technology has resulted in Americans

becoming more sedentary

• Having excess body fat has reached epidemic proportions in this country

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• Overweight:– When an individual has excess body fat

relative to bone structure and height

• Obese:– Individual has a large amount of excess body

fat

• Body Mass Index (BMI):– Used to determine if a person is obese or

overweight– Ratio of person’s body weight to height

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How is fat stored and where do you find it?

• Fat is found in all of the body’s cells

• Essential fat:– Necessary for organ cushioning, temperature

regulation and storing energy

• Non-essential fat:– Accumulates when food intake exceeds

energy demands

• Subcutaneous and visceral fat

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What determines how much fat you have?

• Number of adipose cells

• Size of adipose cells

• Aging process

• Obesity in childhood

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What is body composition?• Body composition:

– Refers to both fat and nonfat components of the body

– The portion of total weight that is fat is the percentage body fat

– Goal is to maximize lean body tissue

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How do you measure body composition?

• Hydrostatic (underwater) weighing

• Bioelectrical impedance

• DXA (Dual Energy X-ray Absorptiometry)

• BOD POD Body Composition System

• Skinfold thickness

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How do you achieve caloric balance?

• If you maintain weight, caloric balance has been achieved– Equal amount of calories in and out

• If the goal is weight gain, increased caloric consumption is necessary = positive balance

• Weight loss requires a negative caloric balance

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How many calories do you expend each day?

• Before planning a weight modification plan you must: – Know how much energy you consume daily– Know how much energy you use daily

• Activity increases the need for energy

• Goal of any diet is to consume enough energy to meet basic needs of tissue and activity

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How many calories do you eat each day?

• A sufficient number of calories is necessary to maintain body weight and composition

• Determining caloric intake requires consulting food composition tables

• Factors unrelated to nutrition often influence food consumption

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Assessing Your Caloric Balance• If logs for estimating caloric intake and

expenditure are accurate, it should be easy to determine caloric balance

• For weight loss, more calories must be expended than consumed

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Set Point Theory of Weight Control

• Set Point Theory:– Hypothesizes that the body maintains a

certain level of body fat– Body has a set point or mechanism for

maintaining a specific body weight– Operates like a thermostat– Unclear how this set point is controlled– Exercise and caloric restriction appear to be

critical in altering the set point

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What can you do to lose body fat?

• Many fat reduction techniques are available:– Some are based on sound scientific and

nutritional principles– Others are dangerous or waste money

• Losing body fat requires a negative caloric balance– Food/caloric consumption must be reduced– Caloric expenditure must be increased

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Losing Weight by Dieting

• Fat loss through dieting alone is difficult• Eating is often influenced by factors

outside of hunger• Periodic dieting is ineffective• Must avoid starvation dieting

– Starvation diets may actually reduce metabolism

• Moderate reduction of total calories are recommended to lose body fat

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Losing Body Fat by Exercising

• Weight loss through exercise results primarily in loss of fat tissue, with little lean body mass loss

• Establishing a new routine is critical and requires motivation to acquire new fitness habits

• Physical activity and caloric restriction at any age can result in substantial weight loss

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• Moderate Intensity Aerobic Activity– Should workout at 60-70% of maximum aerobic

capacity– Exercising above 70% while resulting in increased

calorie expenditure, fewer calories will be from fat• Lean muscle stores will be utilized instead

• Spot Reducing– Attempt at reducing body fat in a specific location– During activity, fat is supplied from all areas of the

body not just in areas where muscle is active

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Losing Body Fat by Dieting and Exercise

• Most efficient method of decreasing percentage of body fat

• Everything in moderation– Caloric expenditure and caloric restriction

combined

• Relatively fast and easy– Easier to generate a negative caloric balance

• Weight loss should not exceed 1-2 pounds per week

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Emphasizing the Long-haul Approach to Minimizing Body

Fat• It takes a long time to accumulate fat and it will

take time to lose it • Many will take drastic measures to speed up the

process– Unfortunately, normal eating habits usually return, as

does the weight– Results in the yo-yo effect– Makes subsequent weight loss more difficult because

body starts protecting fat stores

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Weight-Loss Gimmicks and Fads

• Every year billions of dollars are spent trying to lose weight quickly

• Claims are made about all sorts of products, equipment, programs, gadgets, diet pills…

• People often become bored with the gimmick or fad and lose interest

• There are numerous diets and eating plans available– Must be sure that it is safe and reliable

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Setting Realistic Goals

• Determine a desirable weight relative to height, age and bone structure– Must be reasonable and attainable– If it is too high the person may become

discouraged– Ultimate goal should be reaching a body fat

percentage that is realistic for your age group

• Set a safe rate of weight loss

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Health At Any Size

• Approach to health and well-being that accepts:– Natural diversity in body size– Encourages people to stop focusing on weight

& dieting

• Helps people live well without encouraging size/weight prejudices, phobias, poor body image, or eating disorders

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• Principles:– Accepting and respecting diversity of body size and shape– Recognizing health and well-being are multi-dimensional – Promoting all aspects of health and well-being for people of

all sizes– Promoting eating in a manner which balances individual

nutritional needs, hunger, satiety, appetite and pleasure– Promoting individually appropriate, enjoyable, life-

enhancing, physical activity, rather than exercise that is focused on goal of weight loss

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What if you want to increase lean body mass?

• Can be achieved through muscle work and increased food consumption

• Recommendation for weight gain– 1-2 pounds per week– Weight training must be involved or excess energy

will be converted into fat– Be careful with protein supplements as we typically

consume ample amounts of protein

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What is disordered eating?• Dieting and eating patterns resulting in

overweight and obesity are the most common forms of disordered eating

• For some, weight loss is an obsession:– Becomes a threat to health and well-being– Often linked to body image and societal

pressures – to which the media contributes

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Bulimia Nervosa

• One of the more common eating disorders

• Periods of starvation, bingeing and purging through vomiting, fasting and laxatives/diuretics

• Most common in college-aged women who are average in weight or not excessively overfat

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Anorexia Nervosa• Psychological disease

– Develops an aversion to food and distorted body image

• Person will lose considerable amounts of weight to the point where health is threatened

• 90% of anorexics are female• Appear overly thin to the point where they

lose their feminine shape

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Female Athlete Triad Syndrome

• Syndrome combining disordered eating, amenorrhea and osteoporosis

• Definition may be too broad – as almost any woman may fit this definition