5'4" 160 and falling. I tried on the ninja sumo at a local shop and found the medium and small both fit...but the small fit legthwise the best with legs and sleeves....Obviously I'm a small guy, but by no means a skinny dude. Been dropping lbs. for about two years now and I think I'm almost done. Unsure weather to go with the small or medium...Since the standard ninja is a more athletic fit, I'm not totally sure if the small will work as it did with the sumo ninja.