Lecture 7 Body Composition 1 Lecture 7 1. What is Body Composition? 2. Healthy Body Weight 3. Body Fat Distribution 4. What Affects Weight Gain? 2 1
Body Composition Relative amounts of fat and fat-free mass in the body 3 Healthy Body Weight? 4 2
Unhealthy Body Weight Overweight - body weight that exceeds the recommended guidelines for good health Obesity - body weight that greatly exceeds the recommended guidelines Overweight and Obesity are associated with serious health problems 5 What Is a Healthy Body Weight? GOOD QUESTION!!! A healthy body weight is defined as possessing an acceptable Body Mass Index (BMI) 6 3
Body Mass Index (BMI) BMI is a measure of body weight in relation to height Body Mass Index BMI is a measure of body weight in relation to height 8 4
Body Mass Index BMI Underweight.. Less than 18.5 Healthy weight 18.5 to 24.9 Overweight.... 25 to 29.9 Obese.. 30 9 Body Mass Index There appears to be a U-shaped relationship between BMI and risk of death 10 5
Body Mass Index Not perfect, should be used as a guide BMI may incorrectly estimate risk for some people Those with muscular build, BMI may overestimate body fat The elderly or others with low muscle mass, BMI may underestimate body fat 11 Body Mass Index If you have any concerns, consult a physician! 12 6
Body Fat Percentage Different groups have different body fat expectations: Typical male is 8 to 24 percent; athletes 5 to 10 percent Typical female is 21 to 35 percent; athletes 15 to 20 percent Below a certain body fat threshold, hormones cannot be produced and health problems can occur 13 14 7
Body Fat Percentage Body fat percentage can be measured by: Immersion a.k.a. hydrostatic testing (most accurate) X-ray testing skinfold measurement bioelectrical impedance 15 Body Fat Distribution Where you carry your body fat is important in determining your health risk Abdominal fat vs other types of fat (e.g. subcutaneous fat) 16 8
Body Fat Distribution Abdominal fat (a.k.a. visceral fat) produces chemicals that leach into the bloodstream and increase health risk by lowering levels of beneficial hormones, increasing inflammatory substances and even elevating the bad LDL cholesterol levels. 17 Body Fat Distribution Where you carry your body fat is important in determining your health risk A large abdominal circumference is associated with high cholesterol levels and higher risk for heart disease, stroke, diabetes, and hypertension Obese men tend to accumulate abdominal fat Obese women tend to accumulate hip and thigh fat; however, the onset of menopause shifts weight gain to the abdomen BMI is in healthy range, a large waist circumference may signify an independent risk for disease 18 9
Diabetes and Obesity The rates of obesity and diabetes in the U.S. have risen in parallel 90 to 95 percent of people with diabetes have Type-2, the form strongly associated with obesity Approximately 80 percent of American youth with Type-2 diabetes are obese A reduction in body weight by 7 percent through diet and exercise will reduce the risk of developing diabetes by 58 percent 19 Diabetes and Obesity Not sure what causes IR, but its onset is associated with weight gain caused by diets high in fat and loaded with excess sugar/carbohydrates 20 10
The Problem of Underweight A sudden, unintentional weight loss without a change in diet or exercise level may signify an underlying illness and should prompt a visit to a physician Some individuals have difficulty keeping weight on, and to gain weight, you need to change your energy balance Eating more frequent and energy-dense meals Add nutritional supplements as snacks Reduce aerobic exercise and increase resistance or weight training Underlying medical condition 21 What influences weight gain? 11
Age and Gender Healthy body fat percentage changes as we age: children 12 percent; male adults 15 percent; female adults 25 percent 23 Age and Gender Between the ages of 20 and 40, both men and women gain weight Older adults are susceptible to weight gain and need to be attentive to their lifestyle in order to maintain a healthy weight 24 12
Genetic and Hormonal Influences Parents are obese, an 80 percent chance offspring will be Twin studies suggest genetic tendency toward obesity Two dozen hormones thus far identified play a role in appetite and energy expenditure 25 Hormonal Influences Metabolic rate Thyroid Gland When it is overactive, weight loss will likely result When it is not active enough, weight gain will likely result 26 13
Hormonal Influences Stress!!! Chronic stress increases the amount of fat deposited in the abdomen Stress also affects eating patterns; adrenaline will suppress the appetite, but cortisol stimulates it 28 14
Sleep! 29 Sleep!! 30 15
Obesogenic Environments and Lifestyle Environment influences chances of becoming obese Choice in food is driven by exposure, and cost and convenience Eating out has become a part of daily life When confronted with large serving sizes, people eat more and don t realize it 31 Making Daily Activities More Active Walking: 10,000 steps per day controls weight Inactive people take 2,000 to 4,000 steps per day Stairs: excellent for improving leg strength, balance, and fitness Twice as taxing to heart and lungs as walking 32 16