Why your BMI doesn't tell you everything about your health

When we want to determine if we have a healthy body weight, we often turn to our BMI. NU.nl readers questioned its usefulness. While BMI provides a good indication, it doesn’t tell the whole story about your health, experts tell NU.nl.

The Body Mass Index (BMI) indicates whether you have a healthy weight in relation to your height. But it’s not personalized, as the method doesn’t take factors like gender and age into account.

“It’s a good indication for an average person, but it often gives a distorted view,” says Evelyne Mertens, a dietitian and scientific researcher at the Faculty of Medicine at KU Leuven. “BMI doesn’t take into account fat, muscle, and fluid mass.”

For example, BMI often doesn’t apply to older adults. “They usually have lower muscle mass and higher fluid mass.” The BMI is also not always a good indicator for athletes. They generally have a lot of muscles, resulting in a higher BMI. However, this doesn’t necessarily mean it’s unhealthy.

Pregnant women and breastfeeding mothers also find little use in the measurement method. This is because both body weight and composition change during this period. Additionally, people with an Asian background cannot rely entirely on BMI. They generally have higher fat mass than people with a Western background, according to the Nutrition Center. As a result, they are at greater risk of conditions such as cardiovascular diseases, despite having a similar BMI.

BMI Results

  • Less than 18.5: Underweight
  • 18.5 to 25: Healthy weight
  • 25 to 30: Overweight
  • 30 or higher: Severe overweight (obesity)

You can calculate your BMI by dividing your weight (in kilograms) by the square of your body height (in meters). For someone weighing 65 kilograms and measuring 1.70 meters tall, the calculation would be: 65/(1.70×1.70)=22.5.

Combining with Waist Circumference or Body Fat Percentage Offers Better Results “BMI combined with waist circumference is actually the best indicator,” says general practitioner Stefan van Rooijen. “We know from the latest science that fat around the waist is more harmful than in other parts of your body. This is because vital organs are located there. For example, you don’t want liver fat accumulation, as it affects liver and glucose metabolism negatively.”

Mertens not only looks at weight and height in her clients but also at their lifestyle. “To what extent does someone exercise and eat healthily?” She doesn’t rely solely on BMI. General practitioner Van Rooijen also emphasizes the importance of a healthy lifestyle. According to him, there’s nothing wrong with working on that first. If you can’t achieve a healthy weight independently, it’s wise to consult a general practitioner or a dietitian.

“Especially with a BMI above 30, you should consult a professional, as you can expect immediate health damage, such as cardiovascular diseases. This also applies to long-term overweight. Then people may develop high blood pressure or diabetes. Waist circumference is also important in this regard, as you particularly don’t want too much fat there.”

Waist Circumference Meter Men:

  • Less than 94 cm: Healthy
  • 94 to 102 cm: Elevated
  • 102 cm or more: Too high Women:
  • Less than 80 cm: Healthy
  • 80 to 88 cm: Elevated
  • 88 cm or more: Too high

How Do I Know If I Have a Healthy Weight Myself? You can determine your BMI yourself on websites like the Nutrition Center. For most people, this provides a good indication. Additionally, you can easily measure your waist circumference yourself, explains Van Rooijen. You can do this with a regular measuring tape. “Place the tape around the waist, between the lower rib and your hip bones. That’s about the level of your navel. Breathe out to relax your stomach. And make sure not to tighten the measuring tape too much.”

Mertens recommends also measuring your fat, muscle, and fluid mass. There are special scales that effectively measure these, she explains. You often find these scales in the gym, at the physiotherapist, and at the dietitian’s. What constitutes a healthy fat percentage depends on your age and gender. For men, the percentage ranges from 7 to 25 percent, for women from 21 to 36 percent.

“But it’s also a bit of common sense,” says Mertens. “If you exercise a lot and see that your muscle mass is large for your age, then it’s logical that your BMI is higher than average.”

source: NU.nl

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