There's a surprising amount of energy in your body fat - so much so that one man lived off it for over a year. (image) iStock

There's a surprising amount of energy in your body fat - so much so that one man lived off it for over a year.

Here at Coach, we come across some pretty extreme diet routines on a weekly basis. But nothing – and I mean nothing – comes close to an unnamed Scottish man in 1965 who lost weight by surviving off nothing but his own body fat for over a year.

The origins of this epic fast are as curious as the story itself. Since the end of World War II, and faced with incredible numbers of starving people in Europe, the scientific community became engrossed in discovering just how much, or how little, food someone could eat before negative effects were felt.

But there was only one problem. No scientific journal or university in the world – even in the mid-1960s – could ethically allow their researchers to purposely starve a person for as long as possible.

That was until 1965, when in the middle of a Scottish summer a morbidly obese man walked into the Royal Infirmary in Dundee and told the doctors he was going to starve himself to lose weight.

Despite this man weighing an enormous 207 kilograms, the staff at the hospital advised deeply against total starvation (for rather obvious reasons). But the man persisted, saying he was going to starve himself anyway, and that they may as well monitor his health along the way.

And so began one of the most curious stories of weight loss ever recorded.

Although the entire experiment was documented, analysed and monitored by researchers (and consequently published in a ground-breaking research paper), thanks to doctor-patient confidentiality (and personal preference) the man was never named, and no ID photographs were ever taken.

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Instead, the man was referred to as "Mr A B", and at just 27 years old, was far younger than any other patient who had come to the infirmary suffering from morbid obesity.

For the first seven days of his fast, he lived in the infirmary, surviving off nothing but water and multivitamins. After seven days he was sent home to consume food, but he carried on fasting in his own apartment, only coming in to the hospital regularly to have his carbohydrate metabolism, blood glucose levels and blood pressure levels checked.

Although he did not eat any food, he frequently drank water, and for the first 10 months of his total starvation, the researchers gave him yeast and multivitamins every day to prevent critical nutrient deficiencies from killing him.

The reason doctors administered yeast is simple – it was his only source of protein, and without it, the body starts eating its own muscle tissue. Without any form of protein at all, the man would not be able to "direct" his body to consume his vast amounts of body fat as fuel, and would die within weeks.

Just two tablespoons of nutritional yeast provides a person with 60 calories, 5 grams of carbohydrates and 9 grams of protein – including all nine amino acids, which the human body cannot produce on its own.

At the 100-day mark, or roughly 15 weeks, the doctors noticed that his potassium levels were reaching near-critical lows, and consequently supplemented his yeast and multivitamins with a potassium supplement.

Potassium is an electrolyte that is crucial to the proper working of the heart, as it helps the muscle tissue surrounding the heart to contract properly. Without it, Mr A B would have certainly died of heart failure, as his body would eat into the muscle tissue that kept his blood pumping.

After an astonishing 382 days – or one year and 17 days – Mr A B had reduced his bodyweight from 207 kilograms to just 82 kilograms, a massive loss of 125 kilograms.

Incredibly, when researchers checked back with Mr A B five years after the conclusion of the experiment, he had only regained 7 kilograms, and had no ill effects from the entire year he went without food.

(It must be noted, however, that the research published in the Postgraduate Medical Journal focused purely on the physiological effects of his fast, and not the way it changed his psychological connection to food – which must have been substantial.)

Almost all of Mr A B's daily energy requirements were taken from his vast fat stores which, as it turns out, even relatively lean people can survive on for extended periods.

Dr Karl Kruszelnicki, on his blog Great Moments in Science, theorised that the average male could live off his body fat alone for a couple of days (if you really, really had to).

"The average non-obese 70-kilogram male carries about 8,000 kilojoules of energy in glycogen, and about 400,000 kilojoules in his body fat," wrote Kruszelnicki.

Since the experiment, no media outlet has managed to track down Mr A B, but if he were alive today he would be a relatively skinny 78-year-old who holds the record for the longest fast ever recorded.

Thanks to his insistence on fasting, and regular medical check-ups, he was able to achieve what no experiment could ethically test. He proved that if you were heavy enough, the human body could survive off its own body fat for extended periods of time (albeit with strict medical supervision).

For those of you wondering at home – and I know some of you would ask – Mr A B defecated extremely infrequently during his fast, popping off to the loo just once every 50 days or so.

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