Is 12 hours of not eating considered fasting or it should be 16+ hours?

If you look up "Fasting" in the dictionary it will say it "is a willing abstinence or reduction from some or all food, drink, or both, for a period of time." By that definition, going from lunch to dinner without calories would be fasting.

A definition for an absolute fast (dry fasting) is normally defined as abstinence from all food and liquid for a defined period, usually a period of 24 hours, or a number of days. So usually a day, or a number of days, it still can be no calories between meals.

Some of the skinniest people i know never snack, never drink between meal calories, just eat 3, good sized meals per day.

Some of the biggest people I know have used long-term fasting for weight loss. Just a guess, but I think short-term fasting is very effective, long-term is counter productive.

You can even drink a rich broth, and be considered fasting. In fact that is the healthiest way to go. Just cook a chicken with a lot of vegetables, strain the broth, take the fat off and drink it all day.

that's a short fast...9pm to 9pm of not eating is a fast.....no brkfst, lunch or dinner for a whole day is a fast

If, for whatever reason, you truly want/need to fast, I`d say 24 hrs. is the absolute minimum amount of time to be considered fasting.

3 days

12 hours is considered fasting.

8 hours or more is considered fasting