After Devine published his Devine Index in 1974, Dr. Robinson followed closely only to discover that Devine used estimates. He refocused on the work using empirical data to come up with the Robinson Formula. The formula is based on the belief that the ideal body weight of a man 5 feet tall should be 52 kilograms while that of a woman 5 feet tall should be 49 kilograms. For men who are taller than 5 feet, 1.9kilograms should be added to get their ideal body weight. In the case of women, 1.6 kilograms should be added for every inch above 5 feet.
Measurement instruments
Because the only measurement that is required in this case is height, you will just need a stadiometer.
The procedure of calculating IBW
Using a stadiometer, get the right body height and then apply it in the Robinson formula for ideal body weight given below.
Men: Ideal Body Weight (kg) = 52 kg + 1.9 kg per inch over 5 feet.
Women: Ideal Body Weight (kg) = 49 kg + 1.7 kg per inch over 5 feet.
Example: What is the ideal body weight for a man with a height of 5 feet 3 inches?
Note: 1 kilogram (kg) = 2.2 pounds (lb), 1 meter = 3.28084 feet
The target population
The Robinson formula targets the average population. It cannot be used reliably to get the ideal body weight of very tall or short people.
Pros of Robinson Formula
- The formula makes it very easy to get the ideal body weight even with common height assessment tools.
- As a simple ideal body weight calculation, it can be applied very fast especially in strenuous situations when dosages need to calculated promptly.
Cons of Robinson Formula
- The Robinson formula, just like the Devine formula, uses height as the main measure. By failing to include other factors such as the current weight, the ultimate answer can only be considered an estimate.
- It is only applicable for people within the average height and age. If you are very old, young, very tall, or very short, the formula cannot give the correct results.
Final thought
While the formula introduced some data that was missing in Devine Index, it still lacks a lot because factors that determine the body weight such as current weight and age have been left out. Because of this, a better formula that factors the modern realities would be more appropriate to get the right ideal body weight.
References
1. Robinson JD, Lupkiewicz SM, Palenik L, Lopez LM, Ariet M, Determination of ideal body weight for drug dosage calculations. Am J Hosp Parm 1983 40:1016-9.
2. Pai MP, Paloucek FP, The origin of the "Ideal" body weight equations. Ann Pharmacol 2000; 34:1066-69
3. Stehman CR, Buckley RG, Dos Santos FL, et al, Bedside estimation of patient height for calculating ideal body weight in the emergency department. J Emerg Med 2011;41:97-101
4. Matsuzawa Y, Tokunaga K, Kotani K, Keno Y, Kobayashi T, Tarui S, Simple estimation of ideal body weight from body mass index with the lowest morbidity. Diabetes Res Clin Pract 1990;10(Suppl. 1):S159-64.