Why Body Mass Index doesn’t say anything about whether you’re healthy

Am I slim or too fat? And if so, how overweight am I? In order to estimate your own weight, it is useful and common to calculate the body mass index (BMI). This indicates whether you are underweight, normal weight or just (severely) overweight.

However, BMI says nothing about whether you are actually healthy. Because even slim people can have internal fat deposits and as a result suffer from the classic obesity diseases such as diabetes, high blood pressure and cardiovascular problems.

What is Body Mass Index?

BMI is based on values ​​from the World Health Organization (WHO) and is calculated based on height in relation to weight. It indicates whether the resulting value corresponds to a healthy balance (from a medical point of view).

There are masks for adults over 18 on the internet where you enter your values ​​and the result is displayed. But you can also calculate it yourself: body weight (in kilograms) divided by height (in meters) squared. First, multiply your height by itself: 1.70 (meters) x 1.70 (meters) = 2.89. Then divide your weight by this value, so about 65 (kilogram): 2.89. The value – in this case 22.5 – is your BMI.

So a person who is 170 centimeters tall and weighs 65 kilos has a BMI of 22.5 – and is therefore in the absolute middle of the normal weight range. Anyone who is 185 centimeters tall and weighs 80 kilograms has a BMI of 23.4 – also a good normal value.

According to the WHO, there are six weight classes: under 18.5 means underweight, between 18.5 and 24.9 you are normal weight, between 25 and 29.9 you are overweight, from a BMI of 30 there are three different degrees of obesity (obesity) .

“Based on the mentioned weight classes, it is quick and easy to assess in the first step whether the body fat percentage is too high. The good thing about BMI is that it is so easy to calculate and provides a good initial orientation,’ says ecotrophologist Veronika Albers from the nutritional advice platform Oviva.

You can use the app to get prophylactic advice, help with intolerances, but also get help to lose weight – and it even works with a prescription; the doctor only has to prescribe it, then the app or advice is free or, depending on the insurance company, includes a personal contribution. Around 60 specialists work at Oviva, who provide support via chat or telephone. Veronika Albers is one of them.

Why is BMI not meaningful?

In short, the body mass index describes whether the kilos you carry with you are appropriate, too much or too little for our size. However, it says nothing about how the kilos are distributed – and that is precisely the main point of the criticism. Another is that BMI does not differentiate between fat and muscle. “Athletic people can have an increased BMI value without being overweight,” says Veronika Albers.

Muscle weighs more than fat. Nevertheless, an athlete with a high BMI is usually a very healthy person, whereas a slim person with an optimal BMI may be sick due to internal fat deposits that are not visible from the outside.

“We don’t know what it looks like inside the body,” says Albers. “We can only find out from laboratory values ​​and a visit to the doctor. One result could be elevated liver values, which can be an indication of fatty liver.”

We don’t feel a fatty liver for a long time – too long. Because when the symptoms appear, it’s almost too late. Cirrhosis of the liver can occur, which can be fatal. Warning signs of fatty liver are fatigue, a feeling of pressure in the right upper part of the abdomen, flatulence, a feeling of fullness and nausea. “But there can also be problems with the pancreas or the stomach, which is why precise diagnostics are required,” says Veronika Albers.

Internal obesity, which is not visible, occurs if you eat unhealthy and do little exercise. You can still burn well, so you don’t get fat, but the excess calories are stored in the liver as fat.

It’s like this: If we snack a lot in between, wolf down our meals, eat too many carbohydrates, we automatically eat more than is good for us and than our body actually needs. The excess energy is then stored.

In short, you can have a BMI in the green but still be internally fat and even sick. Then you are thin and fat at the same time.

What are skinny fat people?

As is so often the case, the term comes from English: thin outside, fat inside, abbreviated as the abbreviation TOFI, in German: thin outside, thick inside. “Internal obesity develops over years, it’s insidious,” says ecotrophologist Veronika Albers. “An unhealthy diet and lack of exercise, which results in muscle breakdown, plays a decisive role. However, our muscles are the burners, they use a lot of energy and prevent obesity.”

Those who are classically fat usually have a round stomach (men) or a strong hip and buttock area (women). Fat is visible. But when the liver is fatty, you don’t see it. “The stored fat wraps around the liver so that it can no longer function properly, even though it is our most important detoxification organ,” says Veronika Albers. “However, important conversion and degradation processes also take place in the liver, without which our metabolism cannot function properly.”

You can imagine it as a room where the walls move towards you. “There is a functional limitation of the liver, which in the end can even die out. This cannot be reversed and is really dangerous,” warns the expert. “Because we cannot live without a liver, it cannot be replaced by medicine, only by a transplant.” Without a liver, for example, we would not be able to take medicine because it ensures that the active ingredients do not cause damage in the body.

How do I know if I am healthy?

Aside from the lab results mentioned above and the doctor’s report, it’s generally a good first step to honestly and critically examine your own lifestyle. Do you eat regularly? Do you take the time to chew your food properly? What are you eating? How many vegetables, whole grains, convenience foods do you put on your plate? Do you go to sports? How is the movement in general?

The WHO recommends that you exercise 150 minutes a week, i.e. at least go for a walk. It’s half an hour five days a week. You should also make sure that about half of each meal consists of vegetables and a third of proteins (eggs, tofu, meat, fish, mushrooms, nuts). The remaining third can be carbohydrates, i.e. potatoes, rice, pasta, bread – but preferably from whole grains, because they contain a lot of fiber that makes the intestines healthy.

Now BMI gives a first indication of whether you are carrying too many kilos. However, you can also check how the fat distribution looks – much more meaningful – by taking measurements: Measure the circumference of your waist and hips. Women should have a waist circumference that does not exceed 80 centimeters, for men anything over 94 centimeters is considered problematic. If men have a waist circumference of more than 102 centimeters or women more than 88 centimeters, they are medically classified as obese.

This is a first indication. Now put your waist and hips in proportion by dividing the waist measurement by the hip measurement. The result should not exceed 0.85 for women and less than 1 for men. In men, a critical look at the neck can also help: if rolls of fat form here, it is an indication of overweight.

Finally, you can relate your waist size to your height and age. Measure your waist and divide the number by your height. Anyone under 40 should not have a value higher than 0.5. After this, the limit increases by 0.01 per years of life – 41-year-olds should therefore not achieve more than 0.51, e.g. For people over 50, the limit is generally 0.6 and should not be exceeded with increasing age.

These calculations make more sense than BMI because they take into account a person’s build. A bodybuilder with a high BMI will do well on the Hip-Waist Index, which is closer to reality. And it’s important to look at how old someone is, because metabolism changes over a lifetime. Only the internal, hidden fat deposits cannot be calculated.

This is where you need to be honest with yourself and review your lifestyle if you don’t want to risk liver damage. Slim people in particular should not feel a false sense of security.

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