Fundamentals of Human Nutrition/Body composition< Fundamentals of Human Nutrition
13.2 Body CompositionEdit
Body Composition Makeup and Measuring
The Center for Medical Weight Loss (link), offers a comparison between body weight and body composition. Body weight includes fat, lean body mass, and water. Lean body mass includes muscle, organs, and bone. A standard bathroom scale measures body weight. Body composition refers to the distribution of both muscle and fat in the body. This is often represented as a two part system which includes both lean body and fat weight. A body composition scale provides the user with not only their weight but also the percentage of fat their body contains.
TopEndSports (link) offers information on sports and nutrition. On this website, there is a section on measuring body composition which includes a list of tests which can be used to measure the levels of composition components in the body.
Body Composition Tests
Measurement Skinfold measurement, Girth measurements, Body Weight, Hydrostatic Weighing, Bioelectric Impedance, Dual-Energy X-Ray Absorptiometry (DEXA, Near Infrared Interactance, Total Body Potassium (TBK) , Whole-body Air-Displacement Plethysmography (BodPod), Magnetic Resonance Imaging (MRI), Total Body Electrical Conductivity (TOBEC), Computed Tomography (CT), Total Body Protein (TBP)
Calculations Body Mass Index (BMI), Waist to Hip Ratio, Ponderal Index, Broca Index, Devine Formula, Muscle Mass Calculation, Calculating %bodyfat using skinfolds, Calculating %bodyfat using girths, Somatotype, Weight for Height Tables
Ratings for % Body Fat Levels
There is more than one site that offers information on the types of body composition testing out there. At http://www2.gsu.edu/~wwwfit/bodycomp.html there is a list of body composition testing methods that includes description, accuracy, attire someone should wear for testing, advantages, disadvantages, and even the averagecosts associated with the testing.
On http://www.medicinenet.com/script/main/art.asp?articlekey=56830 , the article written by Jeanie Lerche Davis starts by discussing the old methods such as using measuring tapes and the BMI method. It then goes on to grade the newer methods on a scale from A to F on whether or not the tests do anything to help a person understand body composition; ease and accuracy of methods; and cost.
13.2.2 Body Composition and HealthEdit
Defining Body Composition and Related MeasuresEdit
While the cultural ideal in Western countries focuses much on body composition and its effect on appearance, it is important to remember that body composition is an important indicator of health. Body composition is the ratio of water, lean muscle mass, and fat mass in the body – it is often expressed in terms of percentage body-fat. One related measure for health is body mass index (BMI). BMI is a calculated measure of weight relative to height and there is an established range of BMI values that predict healthy weight.By looking at a BMI chart which has ranges for what values of BMI constitute a person as underweight, healthy, overweight, or obese, a person can clearly see which category he or she falls under. Although this method of body weight measurement provides a general idea of how a person’s weight compares to standards, it doesn’t take into account the proportion of lean mass to fat mass as do body composition measurements.
Differences Between Body Composition and BMI MeasurementsEdit
There are undoubtedly differences between body composition and BMI; however, BMI may be used to estimate body composition and both measures provide valuable health information for the general population. The underlying premise of body composition and BMI measurements is to evaluate how much body-fat one has, and to then predict if that amount of fat puts one at risk for certain diseases. Body composition may be a more accurate measure for disease risk because it shows how much actual body-fat a person has. On the other hand, BMI does not directly measure body-fat, but uses the relationship between one’s weight and height to more or less predict body-fat. Thus, a problem with BMI arises when measuring individuals with lots of lean muscle mass. Active individuals or athletes might have low and healthy percentages of body-fat, but are categorized as overweight or obese by BMI standards. Clearly, the body-fat percentages of these muscular athletes are not putting them at risk for diseases related to obesity. On a similar note, BMI might be a poor choice of measurement when looking at older adults. As individuals age, their height and weight can remain stable, and their BMI values will stay the same. However, older adults are likely to experience sarcopenia and have decreased amounts of lean muscle while their body-fat percentage increases– this alters their body composition and increases disease risk even though their weight and BMI remains constant (Baumgartner, 2006). As previously mentioned, body composition is the ratio of the mass of fat in the body relative to the ratio of fat-free mass or lean mass. Fat-free mass in the body includes mass from bones, water, and muscle. One of the key factors in body composition is body density which is the overall density of the body which can be calculated by adding four individual densities including the density of water, density of fat, density of mineral, and the density of protein. These four components as well as their proportions in the body contribute to body composition and help to determine overall body health. By taking into account factors such as the proportion of lean mass in the body, body composition provides a more accurate depiction of the health of a person when compared to solely measuring the weight of a person and comparing it to his or her height as in BMI. Breaking down a person’s overall mass into components can create a better picture of whether or not a person who is determined “overweight” by their BMI is actually “overweight” or rather is “overfat”. An example of a person who is overweight but not overfat is an athlete who has a high proportion of lean mass that may contribute to a higher number on the scale but not a decreased level of health. A person that is overfat, on the other hand, has a higher proportion of mass from fat which can reflect a decreased level of health. In addition, there are other factors that can contribute to a person being “overweight” such as race. African Americans tend to have higher bone densities than whites which can cause a larger BMI even if the proportion of lean mass to fat mass is equivalent to that of a person of a different race.
Body Composition and Disease RiskEdit
Large percentages of body-fat and the areas of the body where that fat is stored have an effect on the health of an individual. More specifically, visceral fat in the upper-body places individuals at risk for metabolic and heart diseases, cancer, and more (Britton et al., 2013). Men generally have more visceral fat around the abdomen than women. However, both men and women face health risks when they have significant abdominal fat. And in the United States, the number of women with significant abdominal fat has grown more quickly than the number of men who have similar fat deposits (Ford et al., 2004). Women tend to store more fat in the lower body. This fat is also known as subcutaneous fat and poses less risk for heart disease than visceral fat (Karastergiou et al., 2012). Nonetheless, it is clear that maintaining a healthy body composition without excess fat can lower obesity related disease risks.
Body Composition ConclusionEdit
In the end, body composition provides a relatively accurate method in assessing body health and can be helpful in making a person aware of possible disease risks or health issues associated with a high fat mass. It can also help athletes or people looking to gain a higher lean mass percentage keep track of where they stand rather than just looking at a scale and trying to determine whether any weight gained or lost was due to lean or fat mass. No matter how a person measures his or her body health, exercising and eating a balanced diet are the two main ingredients, and following these two lifestyle choices will result in endless benefits reflected in body composition and overall state of health.
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