Prentice6 ppt ch08 (1)

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  • 1. Chapter 8: Limiting Your Body Fat Through Diet and Exercise McGraw-Hill/Irwin © 2012 McGraw-Hill Companies. All Rights Reserved.
  • 2. 8-2 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
  • 3. 8-3 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
  • 4. 8-4 • 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
  • 5. 8-5
  • 6. 8-6 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
  • 7. 8-7 What determines how much fat you have? • Number of adipose cells • Size of adipose cells • Aging process • Obesity in childhood
  • 8. 8-8 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
  • 9. 8-9 How do you measure body composition? • Hydrostatic (underwater) weighing • Bioelectrical impedance • DXA (Dual Energy X-ray Absorptiometry) • BOD POD Body Composition System • Skinfold thickness
  • 10. 8-10 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
  • 11. 8-11 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
  • 12. 8-12 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
  • 13. 8-13 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
  • 14. 8-14 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
  • 15. 8-15 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
  • 16. 8-16 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
  • 17. 8-17 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
  • 18. 8-18 • 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
  • 19. 8-19 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
  • 20. 8-20 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
  • 21. 8-21 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
  • 22. 8-22 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
  • 23. 8-23 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
  • 24. 8-24 • 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
  • 25. 8-25 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
  • 26. 8-26 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
  • 27. 8-27 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
  • 28. 8-28 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
  • 29. 8-29 Female Athlete Triad Syndrome • Syndrome combining disordered eating, amenorrhea and osteoporosis • Definition may be too broad – as almost any woman may fit this definition