Would you fast twice a week? That’s the task set forth in Dr. Michael Mosley’s “The Fast Diet,” the weight loss regimen that has become all the rage in the U.K. The diet prescribes that adherents eat their typical diet five days per week and then spend two days consuming a quarter of their normal calories — what amounts to about 500 for women and 600 for men. If it sounds tricky, Mosley and his following insist that it is only “the least bit painful” — and the results are their own encouragement.

After his doctor informed Mosley — himself, a doctor and television personality — that he was pre-diabetic and overweight and offered to put him on medication to control his cholesterol, Mosley decided to investigate lifestyle changes he could make instead.

“I started off by looking at calorie restriction and saw that the research was really great — it’s pretty much the only thing that extends life,” Mosley told HuffPost. “The problem is it just is impossible to do — I could not imagine myself never eating the things I love. So I started investigating intermittent fasting as a way to control calories.”

In an interview with The Huffington Post, Mosley explained how he spent months researching the latest medical findings on intermittent fasting — the process of drastically varying calorie intake — testing it on himself and watching his cholesterol and insulin resistance go down along with about 19 pounds of fat.

“I went into it quite skeptical because I’ve looked at diets over the years and I’ve always assumed they’re rubbish. Really seriously rubbish,” Mosley went on. “But the people who study in this area are really top scientists — world-class scientists who are hugely reputable in their areas. And they were all coming at it from their areas of expertise: cancer, dementia, diabetes — they were approaching it from different angles, but coming to the same conclusion. I found that very convincing.”

The process was documented in a popular BBC documentary and will run as a three part series on PBS starting on April 3.

Intrigued? Here are seven facts you should know about the diet, straight from Mosley:

1. Intermittent Fasting Is Based On Years Of Research

“There are loads and loads of animal studies going back over 80 years, human studies now going back over about five or six years. And I’ve counted 11 clinical trials of intermittent fasting. There are also [observational] trials on Muslims [who fast] during Ramadan.”

2. ‘Starvation Mode’ Is A Myth

“You know the origin of the starvation mode theory? It was a study done in the 1950s where they took a bunch of young men and asked them to live on approximately half their normal calories and they followed them for six months and they obviously lost dramatic amounts of weight. And when their body fat went down to five percent, they started to experience significant problems. Now that is a really, really radical fast for a really long period of time. That is nothing like simply cutting back your calories for two days a week. It’s a completely different experience.”

3. Medical Discovery Often Begins With Self-Experimentation

“Until you look at it, you don’t realize how many of the great discoveries were carried out by people doing experiments on themselves. There’s a sort of heroic element to it, but also a moral element: these doctors kind of went, “Look, I should try it on myself first.” And actually the first ever long-form documentary I made 20 years ago was about an Australian self-experimenter who was convinced that stomach ulcers were not caused by stress, but by bacteria. So he swallowed the bacterium, developed ulcers and discovered that you could cure it with antibiotics and won the Nobel Prize. There you go.

I think it’s much harder to do now, but actually when you talk to doctors you find that an awful lot of them have tried stuff on themselves. You discover that most of them at some point have tried something on themselves — dermatologists have taken biopsies from their own arms or whatever.

It’s kind of, in a funny way, the moral thing to do: that before you impose it on a rat or one of your fellow human beings, if you really believe in it, you should give it a go yourself. But then obviously, you have to do proper clinical, randomized, double-blind and controlled trials. And they understand the limitations: just doing something on yourself doesn’t really prove anything, but it’s kind of a starting point: you try animals, yourself, a few patients and then you do proper trials. That’s how science progresses.”

4. Intermittent Fasting Helps You Lose Fat, Not Muscle

“There is one advantage that intermittent fasting appears to have over a standard [calorie-restricted] diet: studies suggest that when you do intermittent fasting you lose almost exclusively fat. This is what [researchers] Dr. Krista Varady found and what Dr. Michelle Hoffman found. A standard diet you lose about 75 percent fat, 25 percent muscle. With this, it’s between 85 and 100 percent fat. So when I did it, I lost 19 pounds, nearly all of it fat. My body fat went down from 28 percent to 20 percent. That is important because if you’re going to be doing a diet, you don’t want to lose muscle because the muscle is metabolically active — and muscle makes you look good. Muscle is what you want to preserve at all costs.”

5. Not All Fasts Are Created Equal: Intermittent Fasting Is No Juice Fasting

“I think juicing is a terrible idea. The biggest problem is that it removes the fiber. And the really good thing that’s in fruits and vegetables is the fiber. Fiber reduces your risk of bowel cancers — all sorts of cancers — and it also keeps you satiated and it also stabilizes your glucose levels.

If you take an apple and you eat it, you get loads of fiber in it, it fills you up. Studies show that having an apple before your meal means you’ll probably eat fewer calories in that meal. If you drink apple juice, basically, almost all the skin has been removed and all the vitamins are in the skin. A glass of juice is really just a sugar hit. And that is going to make you feel hungry, it’s going to make your insulin levels go up. It’s going to be empty calories.

And what’s been happening in the last 20 years in the U.S. and also in the U.K. is that people get a huge amount of calories from fluids. They get it from fizzy drinks, but they also get it from smoothies and fruit juices. There are so many calories in those drinks — so much sugar. People think because it comes from an orange that somehow it’s healthy. But actually, when you eat an orange, you’ve got to peel it, it’s got loads of fiber. Once you juice it, all of the good stuff, pretty much, is gone. There are some vitamins, but mostly what you’re getting is fructose.”

6. Dementia Is A Nutrition Issue

“One of the researchers we work with, Dr. Mattsen, has got these mice who are prone to Alzheimers and dementia. And they normally develop dementia at the age of one, which is about middle age for a mouse. When they’re in a fasting state, they go to about two, which is the equivalent of a 90 year old. But if they’re put on fast food diet, they develop it at about four or five months, sometimes six months. So you see the impact of junk food not just on your body, but on your brain. And I think that’s probably one of the more shocking and surprising things.

And I am genuinely worried and most of the people I talk to, scientists, are worried about where we are going. People are living longer, but as we live longer, the risks of dementia climb and how are we going to cope with that? Because you can live with dementia for 20 years and it is an appalling, appalling condition.”

7. ‘The Fast Diet’ Is Still A Work In Progress

“It’s an emerging area — let’s see how things turn out. This is early days and the people who are interested in it and have looked into it are all kind of convinced there’s something there and the question is: How a big a something is it?

The researchers know that intermittent fasting is most beneficial for people who are overweight or obese and we know that if you are successful at losing weight — really at losing fat, because it’s not about weight as much as it is about fat — if you do that, you will reduce risk of diabetes, your risk of heart disease, your risk of dementia. Those are all strongly associated with weight loss. The question is, does it do something beyond weight loss and there’s some evidence it does, but it’s not overwhelming at the moment. And then the question is: is it a better way of losing weight than say a standard diet and there is some evidence that it is. People find it easier to stay on it. They lose more fat and they are able to keep the weight off more easily. Certainly, I found it easy to do.”