Not a doctor, but know some people with weight issues.
My understanding is that you are using a diet plan that the literature warns as being dangerous, (for example losing more that three pounds a week in cases of morbid obeisity) and a doctor is monitoring your vitals and blood work to make sure you aren’t damaging your organs in the process. Essentially they are red-lining your weight loss.
In the most drastic case I’ve ever heard of (second hand) you can actually check into a hospital and they will literally meter your food. If you have a proper metabolic dysfunction they will know because your calories in doesn’t match your weight loss and they can prove it.
There are many documented cases of obese people not eating at all for weeks or months. As long as particular basic needs are taken care of (water, vitamins, minerals), you can live off your own body fat. That's what it's there for.
Of course, as you're running out of it, things go downhill fast.
My understanding is that you are using a diet plan that the literature warns as being dangerous, (for example losing more that three pounds a week in cases of morbid obeisity) and a doctor is monitoring your vitals and blood work to make sure you aren’t damaging your organs in the process. Essentially they are red-lining your weight loss.
In the most drastic case I’ve ever heard of (second hand) you can actually check into a hospital and they will literally meter your food. If you have a proper metabolic dysfunction they will know because your calories in doesn’t match your weight loss and they can prove it.