Dr Giles Yeo arrives for lunch in Cambridge by bike from his research lab at Addenbrooke’s Hospital. In a corner of the Oak bistro he exchanges his clip-clop cycling shoes for a pair of sandals, hangs his fluorescent jacket on a peg, and explains to me the heart monitor that – if he keeps it above a certain daily level – saves him £250 a year on his life insurance. “Their goal and my goal are aligned – neither of us wants them to pay out…” Yeo, 45, is the scientific director of a group studying the effects of genetics on food intake and a pioneer in studies of the cause of obesity. He is, grinning at the prospect of lunch, a somewhat daunting picture of health.
I’m eager to see what he is going to order. His well-timed new book, Gene Eating, debunks much of what we might have taken as read about diet and dieting. It presents the evidence to show that any kind of one-size-fits-all regime is likely to be of little value. He has a gift for describing the science of how our bodies take in calories at different rates and respond radically differently to food groups. Calorie-counting ignores the fundamentals of calorie absorption, and is at best a very rough guide. Much of the trick is to find what works for you.
He scans the menu, aware that I am observing his choices. “I am going for the calves’ liver, because I rarely eat it, and I imagine they do it well here,” he says. “And I will have the lobster bisque to start. I love a bisque.” Are we allowed a glass of wine in the middle of the day, he wonders. He decides we are, and orders a large glass of malbec.
Yeo was born in Singapore and grew up in San Francisco. When he came to Cambridge as a postgraduate, he found the food options “a bit embarrassing”. It’s got better now, he says, not least since this place, a confident neighbourhood French restaurant, opened a decade ago. Still he has been unable to find any decent Chinese food in the city – he has to go to London for that.
When Yeo got into the study of obesity, it wasn’t yet a global growth industry. He started by looking at people with rare genetic disorders, “Kids who literally could not stop eating,” he says – he describes in his book the children who have no off switch to their appetite, and will eat fish fingers from the freezer if left alone.
As he and his fellow researchers began to understand more about how the brain failed to control food intake in extreme cases, they started to see how the disruption of those regular pathways was not unique to severely obese people. There was a spectrum. Yeo left pure genetics and became an accidental neuroscientist. His principal interest is now the genetics of how the brain controls food intake.
In some senses, his work flips thinking about diet on its head. I suggest that as a culture we tend to blame multinationals for delivering hidden fat and sugar to us in ways we find hard to resist – are we wrong in that?
“I think blame is a tricky term,” he says. “Do those companies employ scientists and psychologists who are being paid to make food irresistible to us? Of course, and I think sugary drinks are a particular problem. I just happen to look at potential solutions from the biological perspective.”
Part of this, in very practical terms, is taking steps to keep away from the foods we know we cannot control. “To take a personal, very facetious, example,” Yeo says, “I am not allowed to bring chocolate into the house. I can buy it and have one square, but I will stop at that. If my wife knows there is chocolate around, however, she will eat it all. Now, if there are pork scratchings in the house, for me that is a different story…”
So we have to be honest about what we cannot resist and not have it readily available? I feel compelled to confess my cheese habit.
“Exactly. You want the fat. Now, if the government says in order to solve obesity we are going to tax chocolate, that might work with people like my wife. But it would not work for me and my pork scratchings.”
Yeo tends to lecture without shoes on, which helps his undergraduates remember him, he suggests. “That barefoot guy with no hair, talking about diabetes.” He has the look of a guru, but resists the idea of gurus. He prefers to be directed by the complexities of the science. A bit of his experimentation is on himself. For a recent series of the BBC’s Trust Me, I’m a Doctor on which he is a presenter, he ate vegan for a month. A couple of things happened: he lost about 10lbs and his blood cholesterol levels dropped dramatically.
He believes everyone should at least try it, if only to stop being afraid of eating vegan. With the help of his cycling, Yeo has managed to return to his “vegan weight”. But more importantly he now knows he can eat vegan and cook vegan when he wants. As a result he has reduced his meat intake by about half.
He tends to eat vegan lunches now (the bisque and liver are an exception), because he understands his metabolism better. “I realised if I had a coronation chicken sandwich or something with white bread, I would get very wobbly when I cycled the 14 miles home. But if I had a vegan buddha bowl, I didn’t have the wobbles. That was purely because the buddha bowl takes longer to digest. The white bread carbohydrates would have gone in faster and been used up.”
Was he not tempted to maintain his vegan regime?
He says not. “What I missed the most was eggs. But I should write a book called Magic with Miso, because you realise it is all about finding the umami flavour, that richness you get from a meat stock. If you put a tablespoon of miso into a vegetable casserole, that works…”
Older food cultures understood that principle, he suggests, in the way that they spread meat flavours through their cooking, without relying on the protein itself – he recalls a staple of his own growing up, which used the liquor of a poached chicken to flavour rice. Fish soups, like the lobster bisque he relishes would be another example.
The men in Yeo’s family have always cooked. His grandpa taught him how to kill a chicken when he was six. “He thought you should always be able to look into the eyes of the animal that you will eat. That is why the Chinese tend to leave the heads on their duck and fish. It reminds you that provenance matters.”
Yeo is likeably ruthless in his book in demolishing some of the fad diets that have made their “inventors” rich. “The idea that you should eat alkaline – drink pH9 water or whatever – has absolutely no scientific truth,” he says. “The detox diet is the one that actually costs a lot of money though. I hear Gwyneth Paltrow is opening a store on Oxford Street. I’m amazed they allowed her in.”
He is alarmed by the rise of “orthorexia”, the fear of eating badly, which ascribes pious morality to what’s on your plate. “It narrows your diet and, if you break the rule, leads you into that cycle of depression and despair of other eating disorders.”
I ask how much technology will allow us to customise our attempts at weight loss, and if that is a good thing.
By way of answer he explains how, for another self-experiment, he was recently fitted with an internal glucose monitor of the kind that type 1 diabetics use. “I had all this data about the way I respond to food. I was surprised to find white rice gave me the highest sugar spike of anything, but bread not so much. Everyone would be different, with those peaks.” He hasn’t stopped eating white rice, but is more aware of the consequences. He suggests that eventually you might take a picture of your food and an algorithm will tell you the likely effect on your heart rate and your waistline. “More information has to be better,” he insists.
How about new year resolutions, I wonder, before he gets back on his bike. What would he advise?
“Two things: if you want to lose weight you need a diet to suit your particular lifestyle and your weaknesses. The other thing is: never fear food. Love it, but don’t eat quite as much of it as you want.”
Gene Eating is out now (Seven Dials, £14.99). To buy a copy for £13.19, go to theguardianbookshop.com. or call 0330 333 6846. Free UK p&p over £15, online orders only. Phone orders min. p&p of £1.99.
