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Useful reflections before calculating the ideal weight
Most people, when they hear theneed to lose weight, has in mind a weight to achieve. Let’s stop for a moment to think. Who wouldn’t like to go back to the burden they had in high school or before they got married? But who said that those weights were really right at the time and who can say if they are still right now? The wisest thing to do is get a travel diary on which to begin to write down reflections.
First you have to think about what it was our highest weight as adults, how it felt with that weight, if there were any health problems. How did the comments of friends and family affect us? Then we will have to think about what it was our lowest weight and reflect on how we felt with that weight. The beauty is that there is not only a higher weight and a lower weight. There is also a stable weight and that’s what we tend to go back to whenever we’re not careful about the diet. Higher weight, lower weight and stable weight can guide us but it is also possible to calculate the ideal weight.
How to calculate your ideal weight based on your height
Broca’s formula
The simplest way to calculate the ideal weight based on height alone is the one provided by Broca’s formula:
Ideal weight in women = height expressed in centimeters – 104
Ideal weight in men = height expressed in centimeters – 100
Thus one obtains rather gross estimate of ideal weight. The reasoning behind Broca’s formula is that for every 1 cm increase in height there is an increase of one kilo of body weight and that the difference between man and woman is constant and equal to 4 kg.
There are many other formulas for calculating the ideal weight. All are based on the concept that there must be one proportionality between weight and height.
Lorentz formula
There Lorentz formula provides that the ideal weight in the woman is equal to:
Height expressed in centimeters – 100 – [(altezza in centimetri – 150):2]
While, again according to Lorentz, the ideal weight in men is calculated as follows:
Height expressed in centimeters – 100 – [(altezza in centimetri – 150):4]
Keys formula
Based on the Keys formula the ideal weight is calculated as follows:
Ideal weight in women = (height expressed in meters x height expressed in meters) x 20.26
Ideal weight in man = (height expressed in meters x height expressed in meters) x 22.1
Those mentioned are only three of the many existing formulas. In any case, these are estimates to such an extent that the result obtained can differ significantly between one formula and another.
Practical example
We do a example. Let’s imagine we have a woman whose height is 1.64 meters. Let’s see what his ideal weight is by applying the three formulas mentioned.
- Broca’s formula = 164 – 104 = 60 kg
- Lorentz formula = 164 – 100 – [(164 – 150):2] = 64 – [14:2] = 64 – 7 = 57 kg
- Keys formula = (1.64 x 1.64) x 20.26 = 2.6896 x 20.26 = 54.5 kg
It is understood from this example that the ideal weight prediction formulas they only serve to guide us. Neither of these formulas takes into account the body composition, that is the distribution of weight in fat mass (Fat Mass) and in fat free mass (Fat Free Mass).
If we assume that overweight and obesity must be understood as an expansion of adipose tissue, the fact of establishing the ideal weight on the basis of height alone it can lead to gross mistakes. A body builder, for example, is unlikely to have a body weight close to that interpreted as “ideal” despite his body fat percentage can be close to 3% (just 3 kg of fat on a weight of 100 kg).
What is BMI?
BMI is an acronym which stands for Body Mass Index or body mass index. It is obtained from the ratio between the body weight expressed in kilograms and the square of the height expressed in meters (kg / m2). The World Health Organization has established that starting from a BMI value of 30 we start talking about obesity. Since, like the prediction formulas of ideal body weight, even the BMI does not take into account body composition It is possible that individuals with the same BMI may have significantly different amounts of body fat.
The classification of underweight, normal weight, overweight and obesity based on BMI provides the following:
- Underweight BMI <18.5
- Normal weight BMI 18.5-24.9
- Overweight BMI 25.0-29.9
- Grade I obesity BMI 30.0-34.9
- Grade II obesity BMI 35.0-39.9
- Grade III obesity BMI> 40.0
It was therefore normal weight for BMI values between 18.5 and 24.9. As with all normal ranges, those with 18.5 BMI become underweight losing only half a kilo and those with 24.9, gaining half a kilo, find themselves overweight. The ideal would then be to find each other more or less in the middle of the range with a BMI value of 21.5. Starting from this consideration, a few simple calculations are enough to establish the ideal weight based on the BMI.
21.5 = (ideal weight): (height in cm x height in m)
In the case of the woman taken as an example (stature 1.64 m):
21.5 = (ideal weight): (1.64 x 1.64)
21.5 = (ideal weight): 2.7
Ideal weight = 21.5 x 2.7 = 58.0 kg
The importance of measuring circumferences
The example of the body builder wanted to highlight the limit of body weight prediction formulas. If the goal is to know our nutritional status, it is fine to calculate the BMI but at the same time we must adopt techniques capable of estimating the amount of body fat (bioimpedance analysis, plicometry, DEXA). Another very important step is to evaluate the distribution of fat which, under the influence of genetic and environmental factors, can focus on the waist and abdomen.
Scientific research has amply demonstrated that theaccumulation of fat, especially in the abdominal area, predisposes to dietary diabetes, cardiovascular diseases, cancer and in general to many diseases considered deadly (life-threatening diseases). In recent years, much progress has been made in understanding cause-and-effect relationships between obesity and pathologies concomitants.
The main function of adipose tissue is that of energy reserve. If we introduce more energy than we consume daily we tend to store excess calories in the form of triglycerides at the level of the adipose cell. But what if our adipocytes are already swollen with fat? At each large meal the insulin produced tries to promote further accumulation of fat inside the fat cells. However, if these are already saturated with triglycerides, they become less receptive to insulin and through the secretion of adipokines they push the other fat cells to become insulin resistant too.
In conclusion, when the adipocyte has filled up with fats, the signs of stopping their further deposition are precisely the adipokines. Insulin resistance ends up with a reduced level of adiponectin, considered a protective adipokine, resulting in reduced use of reserve fats as a source of energy. Furthermore, new adipocytes are formed which will trigger the deposition of new adipose tissue. At this point we will have high blood sugar and triglyceride levels circulating, we will lose weight with difficulty, while with great ease we will tend to gain weight: in other words we will be in full metabolic syndrome!
All these phenomena arise mainly at the level of visceral fat. The more visceral fat there is, the greater our propensity to get diabetes and cardiovascular diseases. The amount of visceral fat correlates directly with the waist circumference. Until recently, one was considered normal waist circumference ≤ 102 cm in men and 88 cm in women (as provided by the US National Cholesterol Education Program Adult Treatement Panel III or NCEP-ATP III). Today the International Diabetes Federation (IDF) revised the threshold values defining normal:
- a waist circumference ≤ 94 cm for men;
- a waist circumference ≤ 80 for women.
In conclusion, weight isn’t everything. Apparently thin people with an excess of visceral fat have an increased risk of suffering from metabolic, cardiovascular and oncological diseases.
How to measure your waist circumference
Waist circumference measurement could replace the habit of weighing yourself regularly. It is interesting to note that an increase of 1 kg in one’s body weight corresponds to an increase of 1 cm in the waist circumference. If we think about it this may be an alternative way of establish our ideal weight.
For example, imagine that there is a man whose weight is 100 kg with a waist circumference of 110 cm. By adopting the threshold value established by the IDF, this person will have to lose as many kilos as necessary to bring the waist circumference from 110 to 94. Just do a simple subtraction and it is understood that the kilos to lose are 16 and the weight that we aim to reach is equal to 84 kg.
How should the waist circumference be measured? Just have a tape measure. It is necessary to stand upright with feet together with the abdomen relaxed and the arms hanging on the sides of the trunk. The meter must be placed at the narrowest part of the abdomen at the end of a normal exhalation without compressing the skin.
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