Not healthy at all, every nutrition professionnal will tell you.
90% of people using this "diet" will gain all the weight back; if not more, for lots of reason.
There are direct simple reasons like, by eating much less than your BMR, you are going to loose a ton of muscle mass, even though you eat "enough" protein. The lost of this muscle mass will make your BMR even lower, make your testosterone level lower, and lots of other bad consequences for your hormones.
There are lots of studies about weight loss, comparing every diet, and almost all diets don't work in the long run.
The only thing that works in the long run is eating slightly less calories than needed, with healthy food, with good macros/micros, and building muscle mass, to keep the metabolism rate high.
The thing is, with this type of diet it could take years to achieve your target weight, and not a lot of people are able to accept that, even though it's the healthiest thing to do.
90% of people using this "diet" will gain all the weight back; if not more, for lots of reason.
There are direct simple reasons like, by eating much less than your BMR, you are going to loose a ton of muscle mass, even though you eat "enough" protein. The lost of this muscle mass will make your BMR even lower, make your testosterone level lower, and lots of other bad consequences for your hormones.
There are lots of studies about weight loss, comparing every diet, and almost all diets don't work in the long run.
The only thing that works in the long run is eating slightly less calories than needed, with healthy food, with good macros/micros, and building muscle mass, to keep the metabolism rate high.
The thing is, with this type of diet it could take years to achieve your target weight, and not a lot of people are able to accept that, even though it's the healthiest thing to do.