BMI, ideal body weight & caloric needs

Body mass index (BMI) is a number calculated from a person’s weight and height. It is used to screen for weight categories that may lead to health problems. Calculating our BMI is simple, we just have to use a formula:

BMI (kg/m2) categories:
– <18,5 = underweight
– 18,5-24,5 = normal weight
– 25-29,9 = overweight
– 30-34,5 = obese
– 35-39,9 = severely obese
– >40 = morbidly obese

Being overweight or obese can lead to major health problems, such as cardiovascular disorders (high blood pressure, stroke, heart attack), type 2 diabetes, some types of cancer, kidney disease, locomotion or fertility problems.

Being underweight is also a concern, because it will increase the risk of osteoporosis (brittle bones), amenorrhea (the absence of periods in women), iron deficiency anemia.

Very muscular people, bodybuilders, athletes, may have a high BMI because of their muscle mass, although they are not overweight. BMI may lead to false results in people who have lost muscle mass or older people. So it is not the final solution in deciding if a person is overweight or obese. There are other things that we must have in mind when we make such a statement: waist size, a measure of skinfold thickness and body fat, evaluation of diet and family health problems.

Ideal body weight formulas :

1. Broca’s formula: weight calculation based on height
Ideal body weight (kg) = height (cm) – 100

2. Pende’s formula: weight calculation based on height
Ideal body weight (kg) = height (cm) / 2,4

3. Lorentz’s formula: weight calculation based on height and gender
Men: Ideal body weight (kg) = height (cm)-100-[(height (cm)-150)/4]
Women: Ideal body weight (kg) = height (cm)-100-[height (cm)-150]/2]

4. Lorentz’s modified formula: weight calculation based on height, gender and age
M: Ideal body weight(kg) = {height(cm)-100-[(height(cm)-150)/4]}+[(age-20)/4]
W: Ideal body weight(kg) = {height(cm)-100-[(height(cm)-150)/2,5]}+[(age-20/6]

5. Weight calculation based on height and age
Ideal body weight (kg) = (height (cm)-100)+(age/10)x0,9

6. Creff’s formula: weight calculation based on height, age and body frame
Normal body frame:
Ideal body weight (kg) = (height (cm)-100+age/10)x0,9
Slim body frame:
Ideal body weight (kg) = (height (cm)-100+age/10)x0,9×0,9
Robust body frame:
Ideal body weight (kg) = (height (cm)-100+age/10)x0,9×1,1

7. Monnerot’s formula: weight calculation based on height and wrist circumference
Ideal body weight (kg) = [height (cm)-100+(4 x wrist circumference (cm)]/2

8. Bornhardt’s formula: weight calculation based on height and chest circumference
Ideal body weight (kg) = (height (cm)-chest circumference)/240

9. Weight calculation based on body mass index (BMI)
Ideal body weight (kg) = height (m) x height (m) x 21,75

10. Weight calculation based on gender
M: Ideal body weight (kg) = 50+0,75 x (height (cm)-150)+[(age-20)/4]
W: Ideal body weight (kg) = {50+0,75 x (height (cm)-150)+[(age-20)/4]}x0,90

Methods of determining calorie needs (basal metabolic rate: BMR)

1. Harris-Benedict formula: it is based on weight (kg), height (cm) and age
Men: BMR = 66+(13,7xweight)+(5xheight)-(6,8xage)
Women: BMR = 655+(9,5xweight)+(1,8xheight)-(4,7xage)
We will add 30%, 50% or 100% from the BMR to the previous result, and that is our caloric need (in kcal/day).
30% – for sedentary lifestyle
50% – for those who have a moderate intensity physical activity daily
100% – for those who have an intense physical activity daily

2. World Health Organization’s (WHO) formula: it is based on weight (kg)
Men:
– 18-30 years old: 0,063xweight+2,8957
– 31-60 years old: 0,0484xweight+3,6534
– over 60 years old: 0,0491xweight+2,4587
Women:
– 18-30 years old: 0,0621xweight+2,0357
– 31-60 years old: 0,0342xweight+3,5377
– over 60 years old: 0,0377xweight+2,7545
We multiply the result with 240 and with:
– 1,3 for sedentary lifestyle, or
– 1,5 for moderate intensity physical activity, or
– 2 for intense physical activity.

3. BMR based on ideal body weight and body mass index (BMI)
BMI: 22-25 kg/m2:
– intense physical activity: 31-35 kcal/kg
– moderate intensity physical activity: 26-31 kcal/kg
– sedentary lifestyle: 22-26 kcal/kg.
BMI > 25 kg/m2: our calorie need <22 kcal/kg
BMI < 22 kg/m2: our calorie need >35 kcal/kg
Simplified: you calculate your BMI and search yourself above, then multiply your weight with the calorie need.
E.g.: young person, moderate intensity physical activity daily, weight = 60 kg, height = 1,65 m, BMI = 22,05 kg/m2 = 60 kg x 30 kcal/kg = 1800 kcal/day.

Young persons, growing organisms, pregnant women, women that breast feed, recovering persons have an increased caloric need; on the other hand older people, obese and sedentary lifestyle persons have a decreased caloric need.

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