it can only get unhealthy if you eat way too much fat but that's usually when you're older and i don't even eat that much fat. i tell you it's amazing- i didn't even believe my measurer this morning- i've only been on it for three days(4th today)and i've already lost an inch off my waist and 2 inches on my biggest part right above my hips where i couldn't lose any before!!!also- make sure that after you've lost the weight you want to add in a bit more of carbs so that your body stays healthy because low carb diets creat a sort of ketonosis- which means that your brain is feeding off of ketones instead of sugar and if you do that for too long then it can get unhealthy- but if you do it right then it's wonderful!