Intermittent fasting is one of the latest trends in dieting. It involves several options of fasting that can extremely calorie restrict certain days of the week or restrict you from eating for certain hours out of the day.
People will rave about how effective it is for weight loss and their "numbers" at the doctor. However when intermittent fasting has been studied, its results are similar to that of just old-fashioned calorie restriction. People don't adhere to the diet any better and long-term adherence to the diet is comparable.
But, let me disclose my opinion about both intermittent fasting and extreme calorie restriction. Both methods (intermittent fasting and extreme calorie restriction) will greatly alter your hormones that regulate your hunger. Both will cause metabolic damage which will leave a person who has done either of these methods of dieting with a slower metabolism. This means it's much easier to regain the weight whenever the diet is not maintained.
While your metabolism may be slowed by fasting, there are also several benefits to intermittent fasting. First, your body cleans house and gets rid of any waste during a fast because it's trying to become as efficient as possible. It doesn't have any energy to maintain old cells so out they go. It's a great way to detoxify your body.
Now, while IF and calorie restriction have similar results and similar adherence rates you need to be cautious about this approach if you have a history of body dysmorphia or eating disorders. The practice of extreme calorie restriction followed by time period of re-feeding can promote some eating disorders so if you've got a history of an eating disorder make sure you're doing IF with someone watching you closely with the agreement that you will STOP IF when that person feels it's becoming unhealthy. Better yet, only do IF in collaboration with your physician or mental health team.
My biggest problem with any fad diet- sustainability. If someone cannot maintain diet habits that are made in order to lose weight then weight loss (and all the improved numbers) will only last as long as the diet. IF may be for you if it fits into your lifestyle and you can maintain it. It may not be for you if you find it hard to implement and maintain or you have history of eating disorder.
Any diet changes that are made should be long-term changes. Making gradual changes that you'll stick with is much better for your health than undertaking another fad diet that will leave you with yo-yo weight loss and a damaged metabolism.