I have fasted for 10 then 7 days, then twice I broke the fast on morning of 3rd day due to feeling too bad due to low sugar — like, you make ten steps and you get tunnel vision bad.
For me the first two days are when I feel the worst hunger. The 3rd day is when I feel the weakest. I have about 15kgs of excess weight and I'm already down 4 (most of it has to be water and therefore not sustainable, but the rate is a bit alarming, I might break early due to it). There's also this weird shin pain from yesterday that got quite bad by the night. If it doesn't go away, I'm considering quitting earlier.
I would say fasting is not for everybody. Going for 2 weeks or more you'd definitely would need to supplement micronutrients too, and the time to break is very individual (if hunger returns, then your energy resources are totally up) so don't blindly listen to your mom. That being said, I find it way easier to fast than manage a diet just because of fasting being a simple binary. It also has a side-effect of resetting my taste buds so I don't crave the shit food so much, allowing me to adjust my taste to a healthier one, though I eventually relapse due to how much I can't be arsed to cook. And if worst comes to shove, I already have a CTB plan with several backups anyway so permanent damage to my organism isn't too big of a concern.
I've no idea how fasting on its own affects the gut microbiome (which apparently might be linked to anxiety, meta-analysis
here), but supposedly it's much easier to maintain with a proper diet that in turn gets easier to do after fasting.
