Does anyone know about fasting diet?

It's not the fasting that leads to weight loss, it's the calorie deficit. Fasting is just a tool which some find helpful for managing their deficit.

If you're worried about metabolism slowing you can (and should anyway) periodically return to maintenance levels for a couple of weeks.

12-hour fast shouldn't be hard. Basically it means eating nothing after dinner, which means no late night snacks, which is probably a good thing anyway.

amberchen86 wrote: »

Is it good for long-term weight loss?I read so many articles online said it's good for losing weight but I wonder how can the diet work if your metabolism slow down so much.I can't imaging not eating for 12hours and still have energy to function through out the day.is fasting a fad diet?

Metabolic rate reduces if you lose weight REGARDLESS of how you do it. A lighter person will have a lower metabolic rate than someone heavier.
Where metabolic really would slow down is if you just diet only and don't use your muscles (exercise). Not using your muscles will cause atrophy (loss of muscle) and fool you into thinking you're losing just fat weight.
I fast regularly 12 hours a day. Don't eat breakfast. But carb up by 10:30pm so I have enough energy to workout in the morning. My weight has stayed within 20lbs or so the last 20 years.

A.C.E. Certified Personal and Group Fitness Trainer
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Been in fitness for 30 years and have studied kinesiology and nutrition

"Good for losing weight"
Remember those articles as going to predominantly aimed at people who don't count calories so skipping a meal / having a longer period not eating will most likely cause a calorie deficit for most people. And it's the deficit that results in weight loss.

I've not seen any evidence that metabolism is slowed any more restricting your calories (sensibly) with time restricted eating than a more usual eating pattern.

"I can't imaging not eating for 12hours and still have energy to function through out the day"
You have huge stores of energy stored away as fat and glycogen - that's not a realistic view of simply extending the usual 8 hours unfed when you sleep to 12 or 16 hours. Your energy doesn't have to come from what you have just eaten, a bit like you don't have to top up your car's fuel tanks before very journey.....

"Is fasting a fad diet?"
There are many, many forms of fasting and yes the idea is popular at the moment so that attracts a lot of the diet industry to make fantastic claims to sell books and promote website hits. Yes there are faddish elements hanging around fasting but in reality it's predominantly just a way you can manage your calories. Might suit you, might not. If it makes adhering to your calorie goal easier it's a good match - if it doesn't then it's not.
e.g. If I want to cut some calories then skipping breakfast I find extremely easy but taking the same calories oout of my evening meal would feel very restrictive.

@sijomial said it, but, just to be clear: the 12 hour "intermittent" fast (IF) includes sleep time. Many people don't eat after dinner, and that's when the clock starts. If that's at 8PM, then you get to eat at 8AM, still achieving a 12-hour fast. You could call this "no snacks after dinner," but calling it a "12/12 IF plan" sounds much cooler.

Now, a lot of people wait a few more hours and eat their first meal later in the day (perhaps at noon), so you then have fasted for (perhaps) 16 hours, leaving you 8 hours in which to do your eating before your next fast. You could simply call it "no snacks after dinner and skipping breakfast," but saying "I'm on a 16/8 IF routine" sounds much cooler.

Finally, it can be an interesting challenge to do a 24 hour partial or complete fast every once in a while or on a fixed schedule. The first time I did it was for a colonoscopy prep about 12 years ago. I ate no solid food, but did have tea with sugar and milk. I also drank a sports drink at each meal (about 100kcals each-- the point was to have some electrolytes, could eliminate the sugar). I was amazed how easy it was and it seemed to help me to kick start a cutting phase. On such a day, you can do easy walks and such, but probably not a big workout. Some people do a reduced-calorie (e.g. 500kcal "juice-fast") day twice a week and call it a "5-2 diet."

For all these cases, there are many claims of benefit to blood sugar, etc. There is no question that many of our ancestors lived this way, as access to food was more uncertain. That fact alone doesn't mean it's good for you: they also sometimes starved to death! But, the point is that we are all prone to over-eat and it's sometimes nice to prove to yourself that it's not necessary to eat even every day.

Jthanmyfitnesspal wrote: »

@sijomial said it, but, just to be clear: the 12 hour "intermittent" fast (IF) includes sleep time. Many people don't eat after dinner, and that's when the clock starts. If that's at 8PM, then you get to eat at 8AM, still achieving a 12-hour fast. You could call this "no snacks after dinner," but calling it a "12/12 IF plan" sounds much cooler...

Yes, I lost almost 40 pounds last year on 12:12 IF