I've done some minor adjustments to the style of the icons by adding a supporting text to the bottom of the circles because just seeing the icons with the letters makes it hard to determine what they exactly mean without any hints from a user experience point of view. Here's a mockup of how they'll look like on the site:

Underweight: https://i.imgur.com/F5o8zqT.png
Regular: https://i.imgur.com/HhLXr4S.png
Overweight: https://i.imgur.com/4TSp8AY.png
Mockup: https://i.imgur.com/Hpz1QPj.png

Note: the final sizes of the icons are subject to change. These sizes and styling is purely for experimental purposes. I'll proceed with finalizing them once I'm given the green light.