BMI and Co. – What good is the formula and other indicators?

The BMI is still used for the seemingly objective assessment of the constitution. Doctors in particular still often rely on this simple formula. The BMI is also included in the evaluation of many standardized fitness and health tests (e.g. for health insurance companies).

But can a healthy, fit and attractive body be assessed with an objective formula like the BMI? Are there any other simple indicators that you can use to tell something about your shape?

Who decides what weight you should be? Who determines how the distribution of muscles, fat, water, bones and organs should be? Is it even possible that there is a basic formula that simply “calculates” all people and says whether we are a good weight or not?

That’s what I’ll deal with in this article.

What is the BMI and what does it say?

The Body Mass Index, or BMI for short, was developed in 1832 and is still used as a standard measure for assessing every person. It is a simple formula, with the result of which every person can be quickly assessed on his body condition. To do this, the body weight is simply set in relation to the body size (kg / m²). A first statement about a person’s body condition can only be made with a tape measure and a scale.

The following BMI classification according to the WHO (as of 2008) is used for this:

≥ 40Obesity grade III

BMI Meaning
strong Underweight
16.00 – 16.99 Moderately underweight
17.00 – 18 , 49 slightly underweight
18.50 – 24.99 normal weight
25.00 – 29.99 Pre-obesity
30.00 – 34.99 Obesity grade I
35.00 – 39.99 Obesity grade II

Based on this simple table, it is very easy to determine whether your body is “okay”. It tells you whether you should lose weight or gain weight. There are also gradations according to age and gender. However, these differ marginally and do not change my opinion on the BMI.

Why you should never use the BMI as the sole assessment criterion:

I am 1.80 m tall and currently weigh about 92 kg. The formula gives the result 28.40. That means that I am already clearly in the pre-obese area. That in turn means I am on the verge of obesity and desperately need to lose weight. In fact, I have a little more muscle mass than the average person and with a body fat percentage of currently around 14 to 15%, I am at a healthy level.

Even when I ran my best time at the last Ulm Marathon , for which I really lost a lot and had a single-digit body fat percentage, I was still above normal weight. By the way, during this time I had a pronounced six-pack. 😉

You can see that the formula alone says nothing about a person. For untrained people, the BMI may be a suitable first indicator, but you always have to look at the person individually. In addition, nobody shouldn’t do sports. Today everyone can start small, start exercising and also build muscle mass .

The BMI is completely unsuitable as a self-assessment indicator. Don’t let that unsettle you.

So if the BMI is not suitable for a meaningful assessment, what else is there?

Waist-to-Height Ratio

Another calculation method for the simple assessment of a good and healthy body is the waist-to-height ratio (WHtR for short). It describes the relationship between waist size and height. In contrast to the BMI, this is intended to provide a better statement about the distribution of body fat.
The value is calculated by dividing the waist circumference by the body size.

Age WHtR standard range
40 – 50 0.5 – 0.6
> 50 0.6

Here a sporty person receives a significantly better rating, even if he is a little heavier.

Waist-to-Hip Ratio

Another popular formula is the waist-to-hip ratio (WHR for short). It is calculated from the waist circumference divided by the hip circumference. The areas are distinguished by gender. The German Sports Medical Association has defined the following assessment areas:

WHR women WHR men Interpretation
Normal weight
0.8-0.84 0.9-0.99 Overweight
> 0.84 > 0.99 Obesity

BMI, WHtR or WHR – which formula is the best?

Now we have looked at the most common formulas for a quick assessment of the figure and physical constitution. Which of these formulas should you use as a guide? None of them in my opinion.

In combination, BMI, WHtR and WHR have a greater informative value with regard to the health relevance of overweight, in contrast to the individual results. However, if you want to assess your figure and your fitness / health status simply and objectively, they are still not optimal.

What other, objective assessment criteria are there? Two further, simple assessment criteria could be the waist circumference or the dress size.

waist circumference

A very simple method of assessment is simply measuring the waist circumference. A single measurement with the measuring tape should indicate the dangerous visceral fat (fat lying in the abdomen). Fat is not just fat , this also applies to body fat. This increases the risk of diseases such as heart attack, stroke and type 2 diabetes.

It is measured two centimeters below the navel, at the (most) thickest part of the abdomen. The following values ​​have been established for assessing the medical risk:

I consider the waist measurement to be completely unsuitable as an objective criterion when considering the point in time. However, it can be a useful method to measure your progress. However, it is not the standard values ​​that are decisive, but your personal last measured values.Dress / clothing sizeThe only thing left for a very simple assessment is the size of the clothing. This is still a very popular assessment criterion, especially among women.
However, this is completely unsuitable for an objective assessment and absolutely not meaningful.You should definitely not stick to a certain number here. Every manufacturer has different cuts and size charts. Ultimately, it is important how the clothes look like you and how you feel in them, regardless of the number on the back of the label.KFA – The body fat percentageThe body fat percentage is much more meaningful.
However, this is much more difficult to determine than the BMI or one of the other indicators mentioned above.A simple method is to use an analytical balance. However, it is essential to ensure that you use a high-quality scale with a handle, such as the Tanita BC-545 *, as the upper body is only taken into account in the measurement here.
This can give you many different results. It also gives you an indication of the fat distribution, your muscle mass and the water content of your body.Such electrical impedance scales are comfortable but also have some weaknesses, which is why the results are not extremely precise and stable. They vary e.g. depending on what you have eaten and drunk. However, if you always measure under the same conditions, the results should at least be good enough as a guide when losing weight.Alternatively, you can measure your body fat percentage at different points on your body with a caliper.
With a little practice, this is much more precise when it comes to the subcutaneous fatty tissue, i.e. the visible body fat. I recommend pliers with standardized pressure like the Bozeera body fat pliers *. In this way you avoid deviations due to stronger or weaker pressure when measuring. It should be noted here that this method does not provide any information about visceral fat.If you have now measured your body fat percentage, what does the result tell you?The American Council on Excercise (ACE) provides a simple guide to which KFA has which meaning: 

circumference women circumference men interpretation
80 – 88 cm 94 – 102 cm increased risk
> 88 cm > 102 cm greatly increased risk


women Men Interpretation
10-13% 2-5% Necessary for survival
14-20% 6-13% Athletic
21-24% 14-17% Fit
25-31% 18-24% Average
> 32% > 25% Obese

There are more detailed tables that suggest an adjustment of the ranges depending on age. However, I think this overview is easily accessible and meaningful enough to form an initial judgment.If you are in the uppermost area, you should do something not only for aesthetic reasons, but also for health reasons.Muscle massAnother important indicator for a healthy and aesthetic body is muscle mass or the percentage of muscle mass in relation to body weight. The muscles are of enormous importance for your body.

It protects your body from injury, moves it, is a heat insulator and looks good too. 😉Regardless of the sport, it always makes sense to build up some muscle mass. Most runners would do well to go to a gym at least twice a week and do some muscle building with weights to operate.
With a well-structured strength training, you can easily get some endurance sports complaints under control and even increase your endurance performance.If you want to build up some muscle mass effectively with as little effort as possible, I have created the no-bullshit guide with Muscle Building Basics , which can help you.
The easiest way to measure your muscle mass is with a good analytical scale, like the Tanita BC-545 *.mentioned aboveThere are also guidelines for the muscle percentage. Of course, passionate strength athletes with a low KFA can deviate upwards without this being questionable.

Age women men
up to 19 years 35 – 43% 43 – 57%
20 -49 years 31 – 39% 40 – 54%
from 50 years 27 – 34% 37 – 48%

The whole thing becomes really meaningful in combination with the body fat percentage.Conclusion – what should you orient yourself towards?If you want to find out whether your weight and figure are “okay”, then you shouldn’t rely on the simple formulas and their classifications. These are primarily made to give doctors an initial indication of whether someone has potential health risks due to being overweight.

On their own, however, they are not very useful in this context either.It is better if you pay attention to a healthy body fat percentage and a good musculature, even if these are a little more difficult to determine. If you are not in the danger area here, there is no reason to dwell on absolute values ​​now. Instead, make sure that your development fits what you have set yourself as a goal.Ultimately, what good is it for you, how “good” your body is according to certain norms, as long as you are healthy?
Make sure that you feel comfortable, only compare yourself to yourself, take photos and document your progress. This is how you achieve your goals.If your inner weaker self gets in your way from time to time, you can still have a look at my weaker self killer . In seven steps I will help you to understand yourself better, to set yourself effective goals and to achieve them.
Sporty greetingsAnd don’t forget: Your fitness is your health!I hope you found the article helpful and enjoyed and you will soon come back to the blog. It’s best to follow me directly on Facebook or Instagram and sign up for the newsletter so that you don’t miss any new articles.

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