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10 questions science can’t answer yet
In 2006, Spurlock’s experiment was repeated, this time under controlled laboratory conditions, in Sweden. Fredrik Nyström from Linköping put 18 volunteers on a ‘supersize’ diet – not just McDonald’s, but consisting of an instruction to double their daily calorific intake using junk food, and to avoid physical activity as much as possible (another aspect of Spurlock’s regime). The volunteers were poked and prodded throughout, and a new X-ray technique called DEXA (dual energy X-ray absorptiometry) was used to measure muscle, fat and bone density accurately. A barrage of liver tests and blood cholesterol levels were taken. The works, in short. The results were extremely interesting. The volunteers, unsurprisingly, put on weight, but in wildly differing amounts. One, Adde Karimi, a nursing student, put on just 4.6 kilograms, and half of that was muscle. And this after a month on 6,600 kilocalories a day and virtually no exercise. Additionally, his cholesterol levels actually dropped. Another volunteer put on 15% extra body weight in just two weeks. ‘Some people are just more prone to obesity than others’, Nyström told New Scientist, which reported the experiment in January 2007. Interestingly, none of the first batch of volunteers in the Swedish study suffered the elevated liver enzymes that caused Spurlock’s doctor to make him quit his experiment, although some later volunteers did suffer this sign of liver damage. The message from this experiment? It really is more complex than calories in, calories out. And the message that a high-calorie, fast food diet will inevitably make you ill is probably incorrect. On identical regimes, some people put on weight far more easily than others. It has been clear for some time that the link between diet and cholesterol levels is tenuous, to say the least. But this experiment showed that we may have to throw away our pre-