BODY COMPOSITION

BODY COMPOSITION Chapter 6

TEST YOUR KNOWLEDGE • Exercise helps reduce the risks associated with overweight and obesity even if it doesn’t result in improvements in body composition. True or False? • TRUE. Regular physical activity provides protection against the health risks off overweight and obesity. It lowers the risk of death for people who are overweight or obese as well as for those at a normal weight

TEST YOUR KNOWLEDGE • Which of the following is the most significant risk factor for the most common type of diabetes (type 2 diabetes)? • Smoking • Low-fiber diet • Overweight or obesity • Inactivity • C. All four are risk factors for diabetes, but overweight / obesity is the most significant. It is estimated that 90% of cases of type 2 diabetes could be prevented if people adopted healthy lifestyle behaviors. About 18 million Americans have type 2 diabetes, and more than 6 million of those with diabetes don’t know it.

TEST YOUR KNOWLEDGE • In woman, excessive exercise and low energy (calorie) intake can cause which of the following? • unhealthy reduction in body fat levels • Amenorrhea (absent menstruation) • Bone density loss and osteoporosis • Muscle wasting and fatigue • ALL FOUR. Very low levels of body fat, and the behaviors used to achieve them, have serious health consequences for both men and woman.

BODY COMPOSITION • The relative amounts of fat and fat-free mass • Fat-free mass: all the body’s non-fat tissues: • Bone • Water • Muscle • Connective tissue • Organ tissues • Teeth • Body fat: • Essential fat • Nonessential (storage fat)

Essential fat • Lipids incorporated to the nerves, brain, heart, lungs, liver and mammary glands • Crucial for the body functioning • 3-5% body weight in man 8 – 12% body weight in woman

Nonessential fat • Extra fat or fat reserves stored in the body • Exists primarily in fat cells or adipose tissue • Located below the skin and around major organs • The amount of nonessential fat depends on many factors: gender, age, heredity, metabolism, diet and activity level.

Overweight and obesity • Muscle tissue is denser and heavier than fat, a fit person can easily weight more than the recommended weight on a height/weight table. • For the same reason, an unfit person may weight less than the table’s recommended weight. • It is important to consider body composition – percent of body fat. • Example: • 2 woman  5 ‘5’’ tall weight 130 pounds • One has 15% of body weight as fat • The other has 34% of weight as fat • None of them is overweight by most standards, but the second woman is over-fat

Overweight and obesity • Overweight: The total body weight above the recommended range for good health • BMI ≥ 25 • Obesity: A serious degree of overweight • BMI ≥ 30

Prevalence of overweight and obesity among Americans

Excess body fat and wellness • As overweight and obesity increase, so do the problems associated with them • Risk of chronic disease and premature death • Metabolic syndrome  resistance to the effects of insulin, high blood pressure, high blood glucose levels, abnormal blood fat levels and fat deposits in the abdominal region. • Heart disease • Cancer • Hypertension • Impaired immune function • Gall bladder and kidney diseases • Skin problems • Sleep and breathing disorders • Erectile dysfunction • Pregnancy complications • Back pain • Arthritis • Bone and joint disorders. • Diabetes

Problems associated with overweight and obesity… • Body fat distribution and health • Excess fat in the abdominal area increases the risk of several diseases • Causes are unknown but it appears that abdominal fat is more easily mobilized and sent into the bloodstream

Problems associated with overweight and obesity… • Performance of physical activities • Too much body fat makes physical activity difficult • As a consequence, overfat people don’t exercise • An become less fit. They don’t have muscular strength, endurance and flexibility.

Problems associated with overweight and obesity… • Emotional wellness and self-image • Being perceived as fat can cause discrimination from others • Can contribute to psychological problems such as depression, anxiety and low self-esteem. • The ideal body presented by the media is an unrealistic goal

Problems associated with very low levels of body fat • Having too little body fat is also dangerous • Fat is essential for the functioning of the body • Too little body fat represents • Less than 8-12% in women • Less than 3- 5% in men • Extreme leanness is linked with reproductive, circulatory and immune system disorders and with premature death. • It might also cause amenorrhea in woman and loss of bone mass.

Assessing body mass index, body composition and body fat distribution • Body mass index (BMI) • Measure of body weight that is useful for classifying the health risks of body weight • Based on the concept that weight should be proportional to height • BMI doesn’t distinguish between fat and muscle. • Calculated dividing your body weight (Kg) by the square of your height (m).

Calculate your BMI • Divide body weight in pounds by 2.2 to convert it to kilograms • Multiply height in inches by 0.0254 to convert it to meters. • Multiply the result of step 2 by itself to get the square of the height measurement. • Divide the result of step 1 by the result of step 3 to de3termine BMI.

Assessing body mass index, body composition and body fat distribution… • National Institute of Health NIH guidelines • Consider body fat distribution and other disease risk factors in addition of BMI • Uses the measure of the waist circumference

Assessing body mass index, body composition and body fat distribution… • Percent Body Fat • Underwater weighting • The individual is submerged and weighted under water • The percentages of fat and fat-free weight are calculated from body density • Considers that muscle has a higher density and fat a lower density than water. • Overweight people tends to float and weight less under water • Lean people tend to sink and weight more under water.

Percent Body Fat • Skinfold Measurements • Involves measuring the thickness of skinfolds at several different sites on the body. • You can sum up the skinfold values as an indirect measure of body fatness. • Measured with a device called caliper

Percent body fat • The Bob Pod • Small chamber containing computerized sensors • Measures body composition by air displacement rather than water displacement • Determines the percentage of fat by calculating how much air is displaced by the person sitting inside the chamber

Percent body fat • Bioelectrical Impedance Analysis (BIA) • Works by sending a small electrical current through the body and measuring the body’s resistance to it. • Fat-free tissues, where most water is located, are good conductors of electrical current • Fat is a bad conductor. • The amount of resistance to electrical current is related to the amount of fat-free tissue in the body.

Percent body fat • Advanced Techniques: • DEXA  Dual-Energy X-Ray Absorptiometry • Measures the tissue absorption of high- and low-energy X-ray beams • TOBEC  Total Body Electrical conductivity • Estimates lean body mass by passing a body through a magnetic field.

Assessing body mass index, body composition and body fat distribution… • Body fat distribution • Waist circumference measurement • Waist to hip ratio calculation • Divide your waist circumference by your hip circumference

Setting body composition goals • Establish a goal • Choose a target value for BMI or percent body fat • Make sure your goal is realistic: genetics limits your capacity to change your body composition. • If your body composition is close to the recommended range you might want to set a lifestyle goal rather than a specific percent body fat or BMI goal. • Set a target range for body weight • Don’t stick rigidly to a recommended body weight calculated from any formula, other factors should also be considered

BODY COMPOSITION