This is the thing that really bothers me about the cauliflower substitutions - that it’s being used as a substitute for foods that are meant to offer macronutrients. Cauliflower on it’s own has extremely low calories. It’s meant to be eaten for it’s micronutrients and unique plant compounds. It does not provide enough macros to sustain a person, so if someone were eating a lot of cauliflower in place of their macro-sources they would be putting themselves into a starvation state.
However if any forms of fat and oil are used in it’s preparation, then it might no longer even have the weight loss benefit that might come from that.