you are missing the fibre that the fruit has
which tells you when you need to stop
same reason fruit juice should be avoided
Also the body is fully capable of converting protein into glucose
once your body is in ketosis if will run off stored fat
Sugars also feed parasites.
The biggest problem though is not the food being consumed,
providing it is food not processed junk.
The problem for most is the consumption habits,
eating or drinking sugars for too much of the day.
If doing OMAD or eating withing a 4-6 window you should be good with any food
but consuming any sugars from morning till night
will eventually lead to insulin resistance, and with refined sugars this is more of an issue as much easier to spike your blood sugar than when eating some fruit, as the fibre in the fruit will tell your body that's enough.
The eating window is the most crucial part of any diet,
we are not meant to consume as much as we do.
The body is not a car that always needs some in the tank.