Someone who eats only what the body needs, without craving taste, stays healthy and light. Krishna paints a similar picture of the liberated person: free from desire, mind firmly under control, all accumulation given up. Such a person performs only what the body requires — and incurs no fault whatsoever.
'Only bodily action' means doing what is necessary and nothing more. No hoarding, no scheming, no reaching beyond what the moment asks for. When action is pared down to bare necessity and the mind holds no craving, karma loses its power to bind.