The World Health Organization (WHO) claims an optimal body mass index for adults is between 18.5 bis 24.9. A higher value (>25) is an indicator that you might be overweight or even suffer from obesity. Both are important causes for many illnesses like type 2 diabetes. A value below 18.5 suggests underweight that can lead to serious health implications just like obesity!A lack of nutrients due to insufficient food intake, for example, can lead to fatigue, increased susceptibility to infection and, in the worst case, heart failure.
The simple BMI formula is: body weight in kilograms divided by body size in meters square. The result is used by doctors to categorize ones weight. However, the BMI should not be used to evaluate someone without taking into account the physical fitness. Thus, a sporty man will calculate a higher BMI because muscle mass is heavier than fat. The fat distribution (Waist-to-Hip-Ratio) should also be included in the final assessment. Too much abdominal fat, which is metabolic-active visceral fat, envelops the internal organs and is considered a dangerous fat depot because it increases the risk of heart attacks, arteriosclerosis and alzheimer more than fat deposits on the buttocks or the hips.
Keep in mind: The body mass index is an indicator and is one of many factors that determine your overall physical health.
The BMI of children and adolescents is less significant than for adults since they are still growing. It was therefore collected from the body size and body weight data of a total of 17,147 boys and 17,275 girls in the age group of 0-18 years. Based on the data percentile ranks for boys and girls were created. A percentile stands for a one hundredths. Above the 90th percentile a child is considered overweight, above the 97th percentile an obesity is likely. Children and adolescents between the 10th and the 90th percentile are of normal weight. Below the 10th percentile, doctors assume underweight.
There are many reasons for being underweight including genetic predisposition, thyroid hyperfunction, eating disorders such as anorexia or lack of appetite due to stress or grief. Are diseases the cause of being underweight, a doctor or psychotherapist should be consulted.
Depending on the source, the underweight figures are slightly different. After assessment of WHO are adults with a BMI below 18.5 underweight. The National Research Council of the USA (National Research Council, NRC) staggered the results by age:
Normal weight is a sign of balanced nutrition and physically exercising on a regularly basis - in short a healthy lifestyle. But normal weight is not always normal weight:According to the WHO a BMI value between 18.5 and 24.9 shows normal weight. The US National Research Research Council (NRC), however, grades the ideal BMI by age.
According to a publication of the NRC a BMI between 22 and 25 is associated with the lowest mortality rate and reduces the risk of cardiovascular disease such as hypertension and diabetes. However, the study states that the optimal BMI increases with age. One reason is that in case of a disease a small fat deposit is beneficial since the body can feed from.
In 2015 27.7 percent of americans (18+) are not only overweight but obese. In fact if you combine the obese population with those who are "just" overweight you get a total of 62.9 percent! (Gallup survey among 176.000 citizens of the U.S.A.) In most developed countries it is similar. In Germany 67.1 percent of men and 53 percent of women in Germany have a BMI over 25(survey of the Robert-Koch-Institute).
These figures are disturbing because obesity (i.e. a BMI above 30) is a significant risk factor for chronic diseases , such as diabetes, cardiovascular disease, hypertension and fat metabolism disorders.
The risk for joint complaints grows with increasing weight as well.
However, overweight is not the same as beeing overweight: studies suggest that people with a slight overweight have a longer life expectancy than those with normal weight or less. Reasons for this vary: Persons who are slightly overweight but eat healthy and exercise regularly are healthier than persons of normal weight who eat too much sugar and fat, are not physically active and have a lot of stress. Same for very muscular men, a BMI above 25 does not necessarily mean a higher health risk: muscle tissue is heavier than fat. Dwayne Johnson aka The Rock has a bmi of over 30! Lastly the body also benefits from additional weight in case of illness, because it can feed on stored energy reserves.
The most important thing: you have to feel comfortable in your skin. And your personal feeling is not tied to a number.
Obesity is pathological overweight with a BMI of over 30. According to a DEGS study (study of the health of adults in Germany), 23.3 percent of men and 23.9 percent of women are obese (in the U.S. it´s even higher: 27.7 percent), and the trend is rising. In 1998, obesity was still a mere 19 percent of men and around 22.5 percent of women. According to study results, there is currently an increase in obesity among the 25 to 34-year-olds. One reason for this is the fact that these age groups have grown up with computers, smartphones and entertainment media, but physical exercise declined.
Obesity is associated with a massively increased risk for many diseases, including cardiovascular disease, hypertension, lipid metabolism, fatty liver, but also psychosocial problems. The World Health Organization even accounts 44 percent of diabetes diseases and 40 percent of certain cancer to obesity. The movement apparatus also suffers from obesity, so it supports osteoarthritis in the joints. The German Nutrition Society therefore assumes that obesity is one of the biggest challenges for health care in the 21st century.
If you have a BMI over 30 you should definitely lose weight for your health. A doctor or a nutrition consultant can be of great help.