Question 1

Why is this better than standard BMI?

Accepted Answer

Standard Body Mass Index (BMI) gives a very wide healthy range (often spanning 15-20 kg / 30-40 lbs). It also entirely ignores your bone structure. By factoring in your frame size (small, medium, or large) and using the Robinson formula, we can pinpoint a specific, realistic target number instead of a massive guessing range.

Question 2

Does this account for muscle mass?

Accepted Answer

No. Like most medical weight formulas, the Robinson equation does not differentiate between fat and extreme muscle mass. If you are a heavily muscled bodybuilder or strength athlete, you will naturally weigh more than this "ideal" target, and that is perfectly healthy. This tool is best used by the general population for overall health targeting.

Question 3

How accurate is the finger-wrist test for frame size?

Accepted Answer

The thumb and middle finger wrap test is a widely accepted, highly practical clinical heuristic for quickly estimating bone density and frame size. Since wrists carry very little fat, the circumference of your wrist relative to the length of your fingers provides a surprisingly accurate proxy for your overall skeletal robustness.

Question 4

What is the J.D. Robinson formula?

Accepted Answer

Created in 1983 as an improvement over earlier models, it calculates ideal weight starting at a baseline for a 5-foot person (52kg for men, 49kg for women), and adds a specific weight (1.9kg for men, 1.7kg for women) for every inch above 5 feet. We then apply a ±10% modifier based on the Metropolitan Life Insurance tables to account for frame size.

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