It's generally hard to get Stable Diffusion - even XL - to make "a thin waist" so here's a LORA to fix that.

Huge thanks to Kansakun for putting in a ton of work and time to train this. (My GPU isn't good enough, yet...)

Instructions:

Add the lora and choose a weight. No trigger word is necessary. You can raise the weight up to 1.5 without distortion. If you go higher expect other parts of the body to get bigger in comparison.