For Rick Gallop, author of The GI Diet Book, using traffic-light classifications for food makes dieting that much easier to follow, writes Conor Pope.
This isn't a deprivation diet, it's a pretty balanced diet. You feel satisfied, you don't go hungry," says Rick Gallop, the man behind the GI Diet revolution. Looking healthy and relaxed, with barely a pick on him as he talks with evangelical zeal about the simplicity of his eating programme, he's not a bad advertisement for its effectiveness. He has flown from his Toronto home to England for his mother's 95th birthday but has been diverted to Ireland for a rainy afternoon's proselytising.
Although he didn't invent the Glycemic Index on which the diet is based - the concept was developed by the Toronto-based Dr David Jenkins - Gallop has turned it into gold. Since The GI Diet Book was published in 2003, more than 1.4 million copies have been sold and celebrities from Bill Clinton to Kylie have extolled its virtues.
The Glycemic Index measures the speed at which food is digested and converted into glucose. The faster food breaks down, the higher its GI rating. Sugar, which dissolves into the blood stream rapidly, scores a maximum 100 points and other foods are measured against that.
Unlike many diets which rely on severe mental arithmetic, the forswearing of carbohydrates or a cabbage or grapefruit dependency, the GI Diet appears easy to follow. It's also simplified by Gallop's red, yellow and green "traffic light" classifications.
Red-light foods like butter, mashed potatoes and sugar burn too quickly and won't keep hunger pangs at bay for long, while green-light foods like fruit, vegetables and seafood convert to glucose slowly leaving you feeling fuller for longer.
While his "magic bullet" has been adopted by millions, it owes its existence to an injury to Gallop's back three years ago. Before he strained his back he was in good shape, but suddenly unable to exercise, he started piling on the pounds. It wasn't a good look for someone heading Ontario's Heart and Stroke Foundation, where he worked encouraging weight consciousness.
He tried several diets without success before being introduced to the Glycemic Index. "As luck would have it, the guy who invented the thing was a diabetes specialist living in Toronto." He was using it to stabilise diabetics' blood sugar levels and help them lose weight.
"I started using the GI system and it worked. The only frustration I found was that it was awfully complex because GI doesn't measure other key weight loss factors such as calories and fat." So, to cover these bases, he deployed his traffic light system. "Red-light foods, don't go there; yellow light foods, only when you've got to your desired weight; and green-light foods you can eat as much of as you like."
He wrote the book as a post-retirement project. He is surprised by the "positive feedback" the GI Diet has received because, while he anticipated its health benefits, he wasn't aware of "the emotional baggage people brought with them" when dieting. For women in particular, he says, weight loss can become "a visceral part of their existence".
"There is huge desperation because people have tried all these diets and they don't work. And diets don't work for one very simple reason - people can't stay on them. And why can't they stay on them? Firstly it's because they're too hungry and that's a diet killer." The second thing is complexity and finally, he says, some diets raise long-term health concerns.
But how successful can any diet - no matter how good it looks on paper - realistically be long term in a world where sedentary lifestyles are commonplace? "What I try to emphasise is that exercise is a great way to help you maintain your weight but it's a crummy way to help you lose weight."
One fear dieters have is falling off the wagon "but I say, look, it's not a strait jacket, if you can stay on the diet 90 per cent of the time than you're probably doing better than most people. The worst that can happen is you'll delay reaching your target weight. It is a real world diet. If it's not real world, it ain't going to work."