What Is Body Mass Index

BMI

BMI interpretation

The feeling of being at the top of the game, more energized or physically more active and knowing that we are healthy from inside is wonderful. And it does not take a lot to being to have an impact. we have to recognize that by taking small steps to eat better. We can improve our health by taking small steps to eat better and become physically more active at any stage of life before gaining too much weight. According to National Heart lung and Blood Intitute U.S, obesity associated diseases like high blood pressure(hypertension), high LDL cholesterol("bad" cholesterol), low HDL cholesterol("good" cholesterol), High triglycerides, High blood glucose (sugar), other factors like Family history of premature heart disease, physically inactive, cigarette smoking will put us at greater risk .
J C K Wells and M S Fewtrell explain body composition and growth are key components of health in both individuals and populations. Assessment techniques for measuring body composition includes evaluation of body mass index (BMI) skin fold thickness measurements have been used to rank individuals in term of relative “fatness" or to access the size of specific subcutaneous fat deposits along with other expensive techniques and unavailibity for most clinicians.


Techniques for measuring body composition


Skinfold thickness measurements


Traditionally, skinfold thickness measurements have been used to rank individuals in terms of relative “fatness” or to assess the size of specific subcutaneous fat depots.2 Measurements are quick and simple to obtain in most age groups including young infants. In general, intraobserver and interobserver error are low compared to between-subject variability, but in obese children accuracy and precision are poorer.

Waist circumference


provides a simple measure of central fatness. Excess abdominal fat is an important, independent risk factor for disease. Waist circumference is the most practical tool a clinician can use to evaluate a patient’s abdominal fat. Fat located in the abdominal region is associated with a greater health risk than peripheral fat. Waist circumference measurement is particularly useful in patients who are categorized as normal or overweight. It is not necessary to measure waist circumference in individuals with BMIs = 35 kg/m2 and it adds little to the predictive power of the disease risk classification of BMI. Men who have waist circumferences greater than 40 inches, and women who have waist circumferences greater than 35 inches, are at higher risk of diabetes, dyslipidemia, hypertension, and cardiovascular disease because of excess abdominal fat.


Body mass index (BMI, calculated as weight/height2)


is also widely used as an index of relative weight. In adults, BMI is predictive of clinical outcomes such as type 2 diabetes; however, its predictive value for children and adolescents is less clear. BMI is a global index of nutritional status used to categorise both overweight/obesity and eating disorders in combination with psychological criteria.
According to CDC guidelines, BMI is recommended as a practical approach for assessing body fat in the clinical setting. It provides a more accurate measure of total body fat compared with the assessment of body weight alone. BMI is a direct calculation based on height and weight, regardless of gender.

BMI formula

The formula was created by Belgian Mathematician Adolphe Quetelet in 1832.
based on formula above BMI can be calculated through online

BMI calculators

that are readily available. Besides that another comment tool as given in Dietary Guidelines U.S. Department of Health and Human Services used as an indicator to determine weight status. e.g., BMI chart . Having height in the left most column, and then read across the row from your height to your weight. Follow the column of the weight up to top row that lists the BMI.

BMI chart

Interpretation of body mass index

The range within which a person's BMI falls will help determine whether they are of a healthy weight for their height. The ranges are as follows:

BMI interpretation

Interpretations explanations

as explain in bbc health section someone with a BMI of below 18.5is considered underweight. Whilst some people are naturally slim, being underweight from poor nutrition, or as a result of other disease, can have serious health risks. Illness associated with being underweight ranges from simple tiredness due to inadequate energy intake, through to reduced immunity to infections, anemia, vitamin deficiencies, thinning of the bones, infertility and heart rhythm irregularities. If your BMI is under 18.5 you should discuss it with your doctor. They will want to make sure you don’t have any illness causing the weight loss and then will advise you about how to safely gain weight.
A BMI of 18.5 to 24.9suggests a normal healthy weight. This means your body is not at risk of weight-related disease. You still need to ensure a balanced diet with plenty of fresh fruit, vegetables and good vitamin and mineral intake, but if your calorific intake is matching your energy output you will remain a normal weight.
With a BMI of 25 to 29.9many people may only notice they are overweight when their clothes get tighter - by then the excess weight you're carrying will already have silently started to damage your blood vessels, hormone system and joints, raising your risk of diseases such as: heart disease, High blood pressure, Diabetes, Arthritis, Infertility, Asthma, Cancer. Although you may feel no different, you need to take action whilst the effects of being overweight can be reversed more easily - you need to gently reduce your calorific intake and increase your activity level. Crash diets don’t work - you need to change your lifestyle. Even slight changes make a difference - two less chocolate biscuits, or one less glass of wine a day can lose you 5lb in fat during the year. Simply parking the car at the far end of the car park or using the stairs instead of the lift will over time make a noticeable difference.
With a BMI of 30 to 35 you're now medically classified as obese - this means you're at high risk of weight related illness, such as: heart disease, High blood pressure, Diabetes, Arthritis, Infertility, Asthma, Cancer. But if you can lose even just a little weight your risk will drop - Just a five per cent weight loss (from 80kg to 76kg) has been shown to significantly reduce the health risks associated with obesity, such as reducing your cholesterol levels and blood pressure and giving you better blood sugar control.
To have a BMI over 35is considered as being very obese and this means that obesity-related illnesses could severely affect the quality of your life and shorten your lifespan by several years. Yet even now it’s not too late to do something about it. Improved fasting insulin and thus glycemic control in patients with type 2 diabetes, even coming off the medication you may take for diabetes or blood pressure is possible if you can lose some weight. You should see your doctor and talk about getting help.
If your BMI has reached 40or more you're ‘morbidly obese’ - you will be 80 times more likely to develop type two diabetes than someone with a normal BMI, your lifespan will be shortened by over ten years and your quality of life will be reduced in many ways.


Importance of BMI


Due to ease of use this weight to height ratio(BMI) broadly recognize as a fat assessment method. It provides a more rough means of estimating adiposity(fatness) and identifying trends of sedentary or over weight indiviuals. It matters for you more if we are out of shape office worker who’s life style is more sedentary and don not have much time to pay attention to yourself. This index will indicate your healthy weight ranges and act as predictor of risk of disease and death. According to J C K Wells and M S Fewtrell “BMI is predictive of clinical outcomes such as type 2 diabetes; however, its predictive value for children and adolescents is less clear. BMI is a global index of nutritional status—used, for example, to categorise both overweight/obesity,4 and eating disorders in combination with psychological criteria”.


Limitations


However, BMI has some limitations. For example, BMI overestimates body fat in persons who are very muscular, and it can underestimate body fat in persons who have lost muscle mass (e.g., many elderly). According to WHO "BMI values are age-independent and the same for both sexes”. However, BMI may not correspond to the same degree of fatness in different populations due, in part, to different body proportions. The health risks associated with increasing BMI are continuous and the interpretation of BMI grading in relation to risk may differ for different populations".
BMI may not accurately reflect the levels of 'fatness' of people with builds falling far side the average in different populations(certain population groups in Africa, Asia and north America) as a result of differing body-proportions.In terms of body type and levels of muscularity (referring to somatotypes) Mesomorphs usually have medium builds, while Ectomorphs and Endomorphs would be the lighter and heavier diversions from norms.
BMI cannot be applied to people who have more weight due to higher level of muscles mass (athletes and body builder), they need more accuracy from General Physician.


References