Body frame size refers to the size of the bone structure of your body. Some of us have small frames, some medium and some large.
What size you are will be determined by your genetic characteristics.
The way to measure your body frame size is by measuring your wrist circumference in relation to your height. Once you've measured your wrist circumference, use the following guidelines to determine your size:
You should use your body frame size when you're estimating your ideal body weight – especially when setting realistic weight loss goals for yourself. Knowing this size will also help you understand your ideal BMI and ideal body fat percentage, since the ranges usually specified for a certain weight can vary quite a lot.