Keys explicitly judged BMI as appropriate for population studies and inappropriate for individual evaluation. The interest in an index that measures body fat came with observed increasing obesity in prosperous Western societies. In this paper, Keys argued that what he termed the BMI was "if not fully satisfactory, at least as good as any other relative weight index as an indicator of relative obesity". The modern term "body mass index" (BMI) for the ratio of human body weight to squared height was coined in a paper published in the July 1972 edition of the Journal of Chronic Diseases by Ancel Keys and others. However, the ideal range varies by race, with a BMI that is considered normal for a group of Europeans being unhealthily high for a group of Asians.Īdolphe Quetelet, a Belgian astronomer, mathematician, statistician, and sociologist, devised the basis of the BMI between 18 as he developed what he called "social physics". When used to predict an individual's health, rather than as a statistical measurement for groups, the BMI has limitations that can make it less useful than some of the alternatives, especially when applied to individuals with abdominal obesity, short stature, or unusually high muscle mass.īMIs under 20 and over 25 have been associated with higher all-causes mortality, with the risk increasing with distance from the 20–25 range. Major adult BMI classifications are underweight (under 18.5 kg/m 2), normal weight (18.5 to 24.9), overweight (25 to 29.9), and obese (30 or more). The BMI is a convenient rule of thumb used to broadly categorize a person as underweight, normal weight, overweight, or obese based on tissue mass ( muscle, fat, and bone) and height. The BMI may be determined using a table or chart which displays BMI as a function of mass and height using contour lines or colours for different BMI categories, and which may use other units of measurement (converted to metric units for the calculation). The BMI is defined as the body mass divided by the square of the body height, and is expressed in units of kg/m 2, resulting from mass in kilograms and height in metres. Losing weight and keeping it off is about eating well, moving more, and instilling lifelong healthy habits.Body mass index ( BMI) is a value derived from the mass ( weight) and height of a person. For people above a healthy weight, losing five to ten percent of your weight can lower blood pressure, improve cholesterol levels, and help protect against diabetes and cancer. If you're pregnant, seek advice from your GP or midwife on healthy weight gain during pregnancy. Pregnancy also affects BMI, but a woman’s weight gain during pregnancy is necessary for a healthy baby. Asian ethnic groups).Īlong with BMI, measuring your waist circumference can help you to determine whether you are carrying excess weight around your middle and your risk of heart disease and type 2 diabetes.īecause children are still growing, the BMI calculator on this website is just for adults and should not be used for children. If you're under 18 years of age, seek advice from your GP about what a healthy weight is. It is less accurate as an indicator of overweight in ethnic groups with smaller body stature (i.e.This is because muscle weighs more than fat and the BMI does not take this into consideration. It is less accurate as an indicator of overweight in adults with higher than normal levels of lean body tissue (muscle mass).Obesity is associated with a range of health concerns, including being at an increased risk of heart disease. If you're concerned about your weight, we recommend discussing your result with your GP, practice nurse or dietitian.Īlthough BMI is not a perfect measure, it is generally agreed to be the most useful and valid for adults (18 years and over). However there are limitations. This result means that you may be obese.Carrying extra weight is associated with a range of health concerns, including being at an increased risk of heart disease. If you're concerned about your weight, we recommend discussing your result with your GP, practice nurse or dietitian. This result means that you may be overweight.This result means that you are a healthy body weight which is generally good for your health.Being underweight can be associated with a range of health issues. If you're concerned about your weight, we recommend discussing your result with your GP, practice nurse or dietitian. This result means that you may be underweight.Your risk of obesity related diseases is Try again What is heart healthy eating? The benefits of exercise What does your BMI mean?