Stepping on a scale after a visit to the doctor, comparing the displayed number to a chart found online, and wondering if the result is “good”: the situation is familiar. For a person who is 1.70m tall, the answer depends on much more than a simple mathematical calculation. Height, body composition, age, and morphology come into play, and each formula gives a different result.
Why waist circumference matters as much as weight at 1.70m
Most articles on ideal weight start with BMI. This makes sense, but it is also reductive. Two people who are 1.70m tall and weigh the same can have very different health risks depending on where their fat is stored.
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Abdominal fat, the fat that surrounds the organs, increases cardio-metabolic risk much more than fat distributed on the hips or thighs. A high waist circumference in a person whose BMI is “normal” can signal a danger that the scale alone does not reveal.
Have you ever noticed that two people of the same height and weight can have very different silhouettes? This is exactly the phenomenon. Waist circumference complements the scale to assess real risk. Health professionals recommend measuring it halfway between the last rib and the top of the hip, standing, at the end of a normal exhalation.
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To delve deeper into the issue, it is useful to consult the normal weight for 1.70m according to Zone Santé, which details the commonly accepted ranges based on body type.
BMI for 1.70m: calculation, normal range, and limits
BMI remains the reference used by the World Health Organization to classify body type. The formula is simple: weight (in kg) is divided by height (in meters) squared.
For a person who is 1.70m tall, here is what it looks like in practice:
- A BMI below 18.5 corresponds to underweight (thinness).
- A BMI between 18.5 and 24.9 is considered normal, representing a wide range of weights.
- A BMI between 25 and 29.9 indicates overweight, and above 30, it is referred to as obesity.
BMI does not distinguish between muscle mass and fat mass. An athlete with developed musculature may display a “overweight” BMI while being in excellent health. Conversely, a sedentary person with a normal BMI may have excess visceral fat.
Pregnant women, the elderly, and athletes are profiles for which BMI alone is not relevant. It is a statistical indicator for populations, not an individual diagnosis.
Lorentz and Creff formulas: diverging results
BMI provides a range. The formulas for calculating ideal weight, on the other hand, offer a precise number. The problem: each incorporates different parameters, and the results do not always align.
The Lorentz formula applied to 1.70m
The Lorentz formula takes into account height and sex. For a man who is 1.70m tall, it gives a different result than that obtained for a woman of the same height. This formula ignores age and morphology, making it approximate for individuals outside the “average adult” profile.
Its advantage: it provides a quick reference. Its limitation: it dates back to a time when data on body composition was less refined than today.
The Creff formula: slender, normal, or broad morphology
The Creff formula adds two variables absent in Lorentz: age and morphology. It distinguishes three types of constitution (slender, normal, broad) and adjusts the ideal weight accordingly.
The result varies significantly based on the declared morphology. For the same height of 1.70m, a slender frame will yield a much lower ideal weight than a broad frame. The estimation becomes more personalized, but it remains theoretical.
Why does this distinction matter? Because a person with a broad frame comparing themselves to the result of a formula designed for an average frame risks aiming for an inappropriate, even dangerous, weight.
What BMI does not tell you: muscle mass and fat distribution
You can achieve a perfectly “normal” BMI and still have excess abdominal fat. This phenomenon has a name in medicine: normal weight obesity. It concerns individuals with low muscle mass and fat concentrated around the organs.
Conversely, a weight above the “norm” calculated does not necessarily indicate a health problem. Body composition – the proportion of muscle, bone, water, and fat – provides a much more reliable picture than just the number on the scale.
Tools like bioelectrical impedance analysis (a scale that sends a low electrical current to estimate fat mass/lean mass distribution) allow for a more refined assessment. Their accuracy depends on the quality of the device, but they offer a useful complement to BMI.
- BMI classifies body type on a population scale, not an individual one.
- Waist circumference identifies a cardio-metabolic risk that BMI does not capture.
- Bioelectrical impedance analysis estimates the distribution between fat mass and lean mass.
- The Lorentz and Creff formulas provide references, not medical goals.
Ideal weight at 1.70m: a reference, not a fixed goal
The ideal weight for a person who is 1.70m tall is not a single number. It falls within a range that depends on sex, age, morphology, and level of physical activity. The best indicator remains the one your doctor interprets with your complete history.
The formulas and online calculators are tools for locating oneself. They help position one’s body type relative to statistical averages. They do not replace a clinical examination, a waist circumference measurement, or a body composition analysis.
For a person who is 1.70m tall looking to assess their situation, cross-referencing BMI with waist circumference and, if possible, an estimate of body fat provides a more complete picture than just stepping on the scale. An isolated number never tells the whole story.