The secret life of calories: How to lose weight and be healthier
New Zealand is one of the fattest nations on Earth and a Cambridge University geneticist says we should recognise not all calories are created equal. So what should we be eating? By Eleanor de Jong.
This story was first published in July 2021.
Obesity expert Dr Giles Yeo cycles to and from work each day, runs five kilometres on Saturdays and goes long-distance cycling on Sundays, purposefully searching out hills to push himself. But even then, the University of Cambridge geneticist hasn’t avoided the creep of “middle-age spread”.
In addition to his 20 years as an obesity researcher in Britain, Yeo is also a presenter on the BBC’s popular show Trust Me, I’m a Doctor and BBC Horizon, where his investigations are critically acclaimed.
In 2018, aware of his gradual weight gain, Yeo agreed to adopt a vegan diet for a month and have it documented by the show. Despite veganism having a thoroughly unsexy reputation at the time, the evidence behind it being effective for weight loss is strong.
After a month of tofu, pulses and greens, the effectiveness of the regime seemed indisputable when Yeo lost 4kg and lowered his cholesterol by 12%. Returning from his weigh-in, he celebrated by grabbing a packet of cheese and onion crisps at the train station. That night, he ordered his usual king prawn jalfrezi, naan bread and egg pilau rice at his local curry house, followed by a steak for Saturday-night dinner, roast pork, crackling and goose-fat potatoes for Sunday dinner and a multitude of creamy desserts and wines.
Within five days of quitting veganism, Yeo had regained 50% of his previous weight loss. “That was a shock,” he says, speaking to the Listener from his home in Cambridge. “It was really depressing.”
If even a world-leading obesity expert can’t keep the weight off, what hope is there for the rest of us? “Diets only work if you are actually on the diet,” says Yeo. “When I stopped being vegan, the calorific density of the food I was eating had changed so drastically that the weight was simply flooding back – it’s really, really difficult.”
The YUM factor
A few years ago, Yeo took a test that found white rice gave him a blood-sugar spike shortly after eating it. Yet the knowledge hasn’t deterred him from pairing it with rendang curries and chicken stir-fries. “I hate brown rice!” he laughs.
It is a good example of the psychological finding that even with access to expert knowledge on how to stay healthy and lose weight, humans still have cravings, favourite foods and indulgences they struggle to resist.