Obesity and being overweight are independent health risk factors. Physical inactivity is related to obesity and being overweight. Parents are con¬cerned about children who are overweight. The assumption is that excess weight is fat, so if you are overweight, you are too fat. People of all ages need some fat. Too much fat is unhealthy, how¬ever. The American College of Sports Medicine recommends maximum body fat of 14 to 19 per¬cent for males and 20 to 24 percent for females ages 20 to 60+ years. Body weight is made up of both fat and lean tissue. Remember that lean body mass is muscle, bone, organs, and all tissues other than fat. There is a second assumption about body weight and fat: that the bones are a constant den¬sity or mass. There are differences among races and across age in bone density, so this assump¬tion can be a problem. People who have "light" bones, or osteoporosis, could be in the normal weight range and still be too fat. Someone who has dense bones might be overweight yet have a low amount of body fat. The same could be true of a person who is very muscular. Muscle is dense and, as a result, heavy. Therefore, very athletic people with more than average muscle mass may weigh more than normal and still not have too much fat.
As we can see, body composition is a complex issue. Often, by trying to take something complex and make it simple, we make mistakes. A height and weight chart is simple to use but may not be accurate in determining who is at risk. The Body Mass Index (BMI) is a commonly used measure¬ment; basically, it is a height and weight chart. BMI is body weight in kilograms divided by height in meters squared. Mark McGwire of the St. Louis Cardinals is 6 feet 5 inches tall and weighs 250 pounds; his BMI is 29.7, which would label him with grade 1 obesity. A BMI of 29.7 for a male is significantly higher than that recommended for health, yet in terms of appearance or performance Mark McGwire would not be considered at risk. The point is that with BMI, height and weight can be deceiving. Further, considerable stigma can re¬sult from careless use of norms.
Muscle and bone tissues weigh more than fat and are healthy Individuals who have large, dense bones and greater than average muscle mass are likely to appear overweight based on BMI or height and weight charts, yet they are probably not too fat. On the other side of the continuum are those who have little muscle and bones that are less dense than expected. Very low BMI is also un¬healthy, particularly before 20 years of age. Dur¬ing growth-specifically, before 20 years of age ¬bones gain density. Dense bones have higher fracture points, which means the bones are more difficult to break. Bone density is a result of three factors: genetics, nutrition, and exercise (Bailey 2000, 2001). Adequate calcium and weight¬ bearing exercise produce healthy bones. From about 20 years of age onward, bones lose density.
Two things can be done about this loss: First, the bones should start out as dense as possible, which means that during childhood and adolescence, physical activity and calcium are critical: Second, the rate of loss should be as slow as possible; again, the critical factors are physical activity and calcium. For bone health, being underweight especially of lean body mass-is a greater risk than being overweight.
Study show exercise, is the best thing you can do to live longer. A new study suggest that exercising may be the single most important fac¬tor in extending your life." NBC's Robert Bazell reports the lead story on the March 13, 2002, NBC Nightly News. "A new study offers the strongest argument yet for getting fit. California research¬ers found that the a'6ility to exercise-as mea¬sured on a treadmill test-is more important in predicting how long a person will live than even obesity, heart disease, or smoking."
As we can see, body composition is a complex issue. Often, by trying to take something complex and make it simple, we make mistakes. A height and weight chart is simple to use but may not be accurate in determining who is at risk. The Body Mass Index (BMI) is a commonly used measure¬ment; basically, it is a height and weight chart. BMI is body weight in kilograms divided by height in meters squared. Mark McGwire of the St. Louis Cardinals is 6 feet 5 inches tall and weighs 250 pounds; his BMI is 29.7, which would label him with grade 1 obesity. A BMI of 29.7 for a male is significantly higher than that recommended for health, yet in terms of appearance or performance Mark McGwire would not be considered at risk. The point is that with BMI, height and weight can be deceiving. Further, considerable stigma can re¬sult from careless use of norms.
Muscle and bone tissues weigh more than fat and are healthy Individuals who have large, dense bones and greater than average muscle mass are likely to appear overweight based on BMI or height and weight charts, yet they are probably not too fat. On the other side of the continuum are those who have little muscle and bones that are less dense than expected. Very low BMI is also un¬healthy, particularly before 20 years of age. Dur¬ing growth-specifically, before 20 years of age ¬bones gain density. Dense bones have higher fracture points, which means the bones are more difficult to break. Bone density is a result of three factors: genetics, nutrition, and exercise (Bailey 2000, 2001). Adequate calcium and weight¬ bearing exercise produce healthy bones. From about 20 years of age onward, bones lose density.
Two things can be done about this loss: First, the bones should start out as dense as possible, which means that during childhood and adolescence, physical activity and calcium are critical: Second, the rate of loss should be as slow as possible; again, the critical factors are physical activity and calcium. For bone health, being underweight especially of lean body mass-is a greater risk than being overweight.
Study show exercise, is the best thing you can do to live longer. A new study suggest that exercising may be the single most important fac¬tor in extending your life." NBC's Robert Bazell reports the lead story on the March 13, 2002, NBC Nightly News. "A new study offers the strongest argument yet for getting fit. California research¬ers found that the a'6ility to exercise-as mea¬sured on a treadmill test-is more important in predicting how long a person will live than even obesity, heart disease, or smoking."
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