I find it frustrating when people often discuss experience with 'intermittent fasting' without describing exactly what they mean. The term ranges over lots of approaches. I've seen it used to describe just 8 hours (perhaps every/most days) without food, to a full day or couple of days without food (perhaps every other day or once per week or two), to other things, as is the case here.
The food, during the [5-consecutive-day] period of the restricted diet, was designed to be highly nutritious. It consisted of plant-based soups, kale chips, a nutty bar, a herbal tea and an energy drink. The total number of calories, in five days, was about 2,500 - a little more than the average person consumes in one day. No additional food was allowed. For the rest of the month we were allowed a normal diet. The regime was repeated three times, followed by a control period, when we could eat anything.
8h without food wouldn't be intermittent fasting unless everyone does it when sleeping.
There is one diet type quite popular right now in fitness called Leangains which calls for about 16h of fasting and a 8h eating window (granted that you can reduce the eating window if you feel like it).
Some people even reduce the eating window to just one meal (warrior diet).
For nearly a year, I've been just having coffee with MCT oil in the morning, which pretty much keeps you satiated until 4 pm when I get a light "lunch" and then eat dinner around 9 pm. No hunger ever, no snacking, a few pound of weight loss even though I've increased my calories (get tons from the chunks of grass-fed cheese). Calorie counting is oversimplification of the complex metabolic processes in the human body and ignore major components such as hormones, thermogenesis, etc. Also, I don't get how sane people can accept that boosting your metabolism is healthier (like eating 5 times a day, exercising, etc.). It can't possibly be. Aging is a natural method of dealing the increasing cancer risk. Also, the faster your metabolism is, the sooner you will reach the Hayflick limit!
As vidarh mentionned, you also have to take into accounts macros (carbs/fat/proteins split) and having to eat 3500kcal in 2 meals can be tough sometimes (in the weekend i often do a 6h or so).
I've eaten that way pretty much all my life so it was easy for me to adapt (it mainly consisted of more proteins and alternating more carbs on workout days/more fat on rest days).
That is, in fact, one of the more common forms of IF: one or two days a week, don't eat until the evening meal (and, depending on your specific practice, perhaps eat only lightly then).
If you usually have long enough between meals that skipping breakfast gives you a 16h period without any food, then sure.
When people do leangains they also do tend to focus on getting more protein etc. though, which can turn the 8h eating window into a big ordeal - I struggle to get the calories I need in two meals on Leangains due to the amount of protein I take; I keep wanting to skip the second meal because I'm still so full.
Fortunately, clicking through to another article in the series (http://www.bbc.co.uk/news/magazine-25498742) gives more details about what was tested here:
The food, during the [5-consecutive-day] period of the restricted diet, was designed to be highly nutritious. It consisted of plant-based soups, kale chips, a nutty bar, a herbal tea and an energy drink. The total number of calories, in five days, was about 2,500 - a little more than the average person consumes in one day. No additional food was allowed. For the rest of the month we were allowed a normal diet. The regime was repeated three times, followed by a control period, when we could eat anything.