Fasting on Alternate Days
Most iFasters that use this method will fast for a around a 36 hour period (the duration of a night time sleep and the full day and night following that) and then the following day they eat normally again.
So for example, on Monday, you would eat normally on that day and then on waking the next day you would completely fast or eat only a select amount of calories for full day and night until Wednesday where you would eat normally again. This pattern is then repeated continuously on alternate days.
As you can imagine, this regime is pretty difficult to maintain and I don’t recommend fasting this often or for this long. That’s why a lot of Alternate Day Fasters don’t do a true fast on their fasting days they just limit the amount of calories they eat on the fasting days instead to 15 to 25% of their recommended daily calorie intake.
This study about Alternate day Fasting shows that even if you eat a high fat diet you can still get great weight loss results and health benefits. It does mention however that this method doesn’t give great weight loss results to everyone. Especially those with a bit more abdominal fat to start with and also shows lower success rates in women.
Alternate Day Fasting can be a good option when you’re starting out to help you ease into the idea of fasting. So you could limit your calories on two days of the week (preferably a few days apart) for one or two weeks before trying two 24 hour fasts a week.
If you want to try ADF as your fasting method of choice you can get started by calculating your daily calorie needs using this calculator and then start with eating say 30% of this amount on your fasting days and then drop that back to 25% after two weeks, when you know you can keep it up continuously.
Alternatively my preferred method (which seems to work very well for many women) is a mix of ADF and true fasting where you limit your calories to 25% as per the ADF style on Monday and Tuesday every week (or the days of your choosing) and make sure that there is one 24 hour window of true fasting during the two days. For example Monday lunch time to Tuesday lunch time, or Monday dinner time to Tuesday Dinner time.
Then once you’ve done that then that’s all you need to do for the entire week.