Obesity is a medical condition in which excess body fat has accumulated to the extent it has adverse health effects. Relative weight and body mass index (BMI) are almost identical and a reasonable estimate of body fatness as measured by body fat percentage. However, BMI does not account for the wide variation in body fat distribution, and may not correspond to the same level of obesity or associated health risks in different individuals and populations. Other measures of fat distribution include waist-to-hip ratio and body fat percentage. Normal weight obesity is a condition of having a normal weight, but a high percentage of body fat with the same health risk of obesity. BMI can be used to predict the risk of metabolic abnormalities such as diabetes.
Video Classification of obesity
BMI
Body mass index or BMI is a simple and widely used method for estimating body fat mass. BMI was developed in the 19th century by Belgian statisticians and anthropometry Adolphe Quetelet. BMI is an accurate reflection of the percentage of body fat in the majority of the adult population. However it is less accurate in people like body builders and pregnant women. A formula combining BMI, age, and sex can be used to estimate the percentage of a person's body fat with an accuracy of 4%. An alternative method, body volume index (BVI), is being developed by the Mayo Clinic in an effort to better account for the different body shapes. BVI measures the body fat distribution and computes the BVI number, based on this result. This BVI figure is an indication of the weight associated with health risks.
BMI dihitung dengan membagi massa subjek dengan kuadrat dari tinggi badannya, biasanya dinyatakan baik dalam metrik atau unit "Adat" AS:
- Metrik:
- AS/Adat dan imperial:
The most commonly used definition, established by the World Health Organization (WHO) in 1997 and published in 2000, gives the values ​​listed in the table to the right.
Some modifications to the WHO definition have been made by certain agencies. Surgical literature breaks class III obesity into a further category, although the exact value is still debatable.
- Each BMI> = 35 is severe obesity
- BMI> 40 is morbid obesity
- BMI> 50 is super fat
As the Asian population develops negative health consequences for lower BMIs than Caucasians, some countries have redefined obesity. The Japanese have defined obesity as a BMI of over 25 while China uses BMIs greater than 28.
The definition based on BMI is easy to use and is well suited for statistical purposes, as it relies only on two commonly measured quantities, height and weight of a person. However, he ignores the variation between individuals in the amount of lean body mass, especially muscle mass. Individuals involved in heavy physical work or exercise may have high BMI scores despite having less fat. For example, more than half of all NFL players are classified as "obese" (BMI> = 30), and 1 in 4 are classified as "very fat" (BMI> = 35), according to BMI metrics. However, the percentage of their average body fat, 14%, is in a range that is considered healthy.
The preferred obesity metrics in scientific circles is the percentage of body fat (BF%) - the ratio of the total weight of a person's fat to their body weight, and BMI is seen as just a way to estimate BF%. Rates of more than 32% for women and 25% for men are generally considered to indicate obesity. However, accurate measurement of body fat percentage is much more difficult than BMI measurement. Several methods with varying accuracy and complexity exist.
Other proposed but less common obesity measures include waist circumference and waist-hip ratio. It measures the general form of obesity known as abdominal or central obesity, characterized by excess fat in the abdominal area and within the peritoneal cavity. They have proven to be comparable to BMIs in their strength to predict the risk of metabolic abnormalities such as type II diabetes, and may be superior to BMI as a predictor of cardiovascular disease.
Maps Classification of obesity
Waistline and waist-to-hip ratio
In the United States waist circumference & gt; 102 cm (~ 40 ") in males and & gt; 88 cm (~ 34.5") in women or waist-to-hip ratio (waist circumference divided by hip & gt; 0.9 for men and & gt; 0.85 for women) is used to determine central obesity.
In the waistline of the European Union >> = 94 cm (~ 37 ") in men and> = 80 cm (~ 31.5") in non-pregnant women is used as a cut off for central obesity.
Pieces lower than 90 cm have been recommended for South Asian men and Chinese, while 85cm pieces have been recommended for Japanese men.
In those with a BMI under 35, intra-abdominal body fat is associated with negative health outcomes independent of total body fat. Intra-abdominal or visceral fat has a very strong correlation with cardiovascular disease. In a study of 15,000 people, waist circumference also correlated better with metabolic syndrome than BMI. Women with abdominal obesity have cardiovascular risks similar to men. In people with a BMI of more than 35, measurement of waist circumference but slightly increase BMI prediction because most individuals with BMI have abnormal waistlines.
Body Volume Indicators
The Body Volume Indicator (BVI) is a noval method for calculating the body fat distribution. Designed by Select Research and Mayo Clinic (the Mayo Clinic review), BVI has been developed as an alternative to BMI (Body Volume Indicator). BMI does not take into account the muscle and fat distribution, or sex, or ethnicity; and therefore not an accurate measure of obesity in many individuals. BVI uses 3D technology to analyze overall body shape, identifying where fat is distributed throughout the body.
Body Volume means the composition of a person and parts of his body; every part of a person's body (arms, legs, chest, etc.) has its own 3D shape, weight and individual size. The increased volume of fat and muscle usually corresponds to an increase or decrease in volume in that area of ​​the body. BVI calculates the body fat composition of a person from two images taken front and side. The silhouette is extracted from these images and a 3D model is created, from which linear measurements and detailed volumes can be calculated. By comparing the 3D model with MRI data, the BVI software is able to calculate the distribution of fat, and especially visceral fat accumulated near individual organs. The results will provide accurate measurements for waist to hip ratio, BMI, total body fat, visceral fat and BVI numbers.
The BVI number has been designed by the Mayo Clinic as an alternative to BMI. This provides an indication of health risks based on fat distribution with particular emphasis on visceral fat; which is located around the organs. Visceral fat is metabolically active, with a high level of known risk factors for cardiovascular disease and type II diabetes.
Percent body fat
Percentage of body fat is total body fat expressed as a percentage of total body weight. There is no generally accepted definition of obesity based on total body fat. Most researchers have used & gt; 25% in men, and & gt; 30% in women, as a cutoff point for defining obesity.
Persentase lemak tubuh dapat diperkirakan dari BMI seseorang dengan rumus berikut:
- di mana jenis kelamin (jenis kelamin) adalah 0 jika perempuan dan 1 jika laki-laki
This formula takes into account the fact that the percentage of body fat tends to be 20 percent greater in women than in men for a given BMI. It acknowledges that the percentage of one's body fat tends to increase with age, even if their weight and BMI remain constant. The results of this formula have been shown to have 4% accuracy in one group of individuals.
There are many other methods used to determine the percentage of body fat. Hydrostatic weighing, one of the most accurate methods of calculating body fat, involves weighing a person under water. Two other simpler and less accurate methods have been used historically but are now not recommended. The first is a skinfold test, in which a pinch of skin is accurately measured to determine the thickness of the subcutaneous fat layer. The other is a bioelectric impedance analysis that uses electrical resistance. Bioelectrical impedance has not been proven to provide more benefits than BMI.
Body fat percentage measurement techniques used primarily for research include computed tomography (CT scan), magnetic resonance imaging (MRI), and dual-energy X-ray absorptiometry (DEXA). These techniques provide very accurate measurements, but are difficult to obtain in very obese patients because of the weight limitations of most equipment and insufficient diameter of many CT or MRI scans.
Childhood obesity
A healthy BMI range varies with the age and sex of the child. Obesity in children and adolescents is defined as a BMI greater than the 95th percentile. The reference data that this percentile is based in 1963 to 1994 and thus has not been affected by recent increases in obesity rates.
Childhood obesity has reached epidemic proportions in the 21st century with increasing numbers in both developed and developing countries. Obesity rates in Canadian boys have increased from 11% in the 1980s to over 30% in the 1990s, while over the same time period this increased from 4 to 14% in Brazilian children.
As with obesity in adults, many different factors contribute to the increasing rate of obesity in children. Changing diet and reducing physical activity is believed to be the two most important in causing a recent increase in obesity rates. The activities of self-transport, physical school education, and organized sports have declined in many countries.
Because obesity in childhood often continues into adulthood, and is associated with many chronic diseases, it is important that obese children are tested for hypertension, diabetes, hyperlipidemia, and fatty liver.
Treatments used in children are lifestyle intervention and behavioral techniques. Drugs are not FDA approved for use in this age group.
See also
- Alometry
- Body adipocyte index
- Body adiposity index (BAI)
- Body fat percentage (BFP)
- Body Mass Index
- Body Shape Index
- Contents volume index
- Body water
- Self-Victim Index
- List of countries by Body Mass Index (BMI)
- Paradoxic obesity
- Pignet Index
- Abdominal Sagittal (SAD) Diameter
- Waistline hip ratio
- Waist-to-high ratio (also called waist-to-stature ratio (WSR))
References
- References
Source of the article : Wikipedia
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