Does testosterone make your jaw bigger?

The face grows unevenly through adolescence, and the lower face is among the last parts to finish. Sex hormones are part of what makes that late growth differ between boys and girls, which is why adult male faces tend to have a broader mandible, a more prominent chin and a stronger brow ridge. The glossary calls this set of differences sexual dimorphism. Genes, nutrition and timing all play a part, so two men with similar hormone levels can still end up with very different jaws.

If you are still in your teens, your jaw is probably not finished. A soft lower face at sixteen says little about the face at twenty-two, and there is nothing safe to do that speeds the process up.

Once growth has finished, the bone that sets jaw width, the gonial angle and the chin is structural. Higher testosterone does not regrow it. Hormones do affect muscle and where the body stores fat, so a change in either can change how the lower face reads. That is soft tissue moving over the same bone, not a bigger jaw. Low testosterone can come with more body fat, which softens the outline, but the bone does not shrink. The BecomeTen evidence library has no study on testosterone and jaw shape, so this page cites none.

• Body fat. The largest workable lever. Fat along the jaw and under the chin hides whatever bone is there. See how to make your jawline show.
• Posture and camera. Head level and lens at eye level let the corner of the jaw show. A low phone or a forward head blurs it.
• Beard. A short, shaped beard draws a firmer edge. It is presentation, not bone.

To see where your jaw stands today, the free jawline test separates the angle from the softness over it, and what a weak jawline looks like explains which part is fat and which is bone.