Your weight. This is the typical parameter

Your weight. This is the typical parameter, which can give you any scale (remember weigh yourself without clothes). With your weight you can also calculate your BMI (or BMI), which gives a ratio of your weight and height (here's how to calculate it and how to interpret the results). Think that BMI can be quite misleading, since two people with the same BMI may have a very different body composition (different% fat and muscle), so it is very important to know the% fat.
Your level of body fat: There are several mechanisms that give you information on your% body fat approximate, as the use of plicómetros or caliper (you can get one for less than 20 euros) or using impedance, which is the one used advanced scales in any store selling fitness. Both methods are approximate, so ideally use both and you obtain the average. There are more accurate methods such as hydrostatic weighing or ultrasound, but require more complicated apparatus, which are not very practical. Amabella Guidance ranges for men:
> 30%: obese, typically with a large 'beer belly'.

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