I recommend drastically limiting snacking to prevent metabolic issues. Our current model of feeding children, in which it is considered nearly child abuse to expect a child to go from one meal to the next without a juice box and crackers, has resulted in epidemics of both childhood obesity and diabetes.
However, growing children need nutritients to grow, and I do not recommend limiting food beyond 3 meals a day.
Teenagers and young adults (under about 22-25) should not fast for similar reasons, because their bodies are still developing. Though I think a bit more fasting is OK. Going down to 2 meals a day is probably OK, even the occasional OMAD.
I do not think pregnant or breastfeeding women should fast. Growing an entire other person requires a lot of nutrition.
If you are in one of those categories and have fat you wish to lose, I would recommend a ketogenic diet, but postponing fasting to a better time.
However, if your BMI is less than 20, you don't have much fat to lose, any fasting beyond 24 hours is not recommended. And if you know you're malnourished, your body doesn't have the stored nutrients to do well during a fast. If you currently have adrenal insufficiency and your treatment does not support your adrenals very well, you may get ill from any detox that occurs. Finally, if you've ever had refeeding syndrome, I'd be extremely cautious about considering any future fasts. The purpose of fasting is to heal your body; don't be stupid and cause harm instead!
