What Neuroscience Can Tell Us About Nutrition

Plus, why doctors are urging governments to take action

Pressmaster / Shutterstock
Pressmaster / Shutterstock

Extreme obesity can knock eight years off your life, according to one Canadian study. But even being overweight has a clear impact on how we age. One study found that obese people had substantially less white matter in their brains than leaner people. While our brains naturally shrink with age, the brains of the obese people were found to have a comparable white matter volume to a lean person 10 years their senior. The impact on cognitive function is not known, but it’s unlikely to be good.

Obesity is the main cause of type 2 diabetes, which is most prevalent in older people. The number of Brits with type 2 diabetes has doubled in 20 years and it now accounts for almost 9 per cent of the annual NHS budget. A third of Americans over 65 now have type 2 diabetes. The consequences can be really nasty: blurred vision, sores which won’t heal, even toe, foot and leg amputations.

Type 2 diabetes develops when our bodies consume so many carbohydrates that the pancreas ceases to release the right amounts of the hormone insulin into the blood, to regulate the glucose that gives us energy. Our systems are overwhelmed and they fail.

People who head into their sixties obese are storing up real trouble in Extra Time. Doctors are wary of interfering, because they feel that what we eat is a ‘lifestyle choice’. Personally, I’m not so sure how much of a choice it is. Public health agencies have spent decades exhorting people to lose weight with almost no effect. I have become convinced that one reason we find it so hard to lose weight is that junk food–especially sugar–is addictive.

The Story of the Sugar Tax

When I served on the board of the Care Quality Commission, the national regulator for hospitals, the scourge of obesity was every-where. Hospitals were having to reinforce beds for super-sized patients. Doctors were refusing knee replacements to people who were so overweight they feared the replacements would buckle under the strain. Some of those people became less active because their joints hurt and so gained even more weight. It was a terrible vicious cycle.

Around the same time I watched a talk by the American paediatric endocrinologist Professor Robert Lustig. He argues that sugar is the main cause of obesity, because sugar is as addictive as nicotine and switches on the same hormonal pathways which reward behaviour. Low blood sugar affects mood, concentration and the ability to inhibit impulse. Eating or drinking something sugary reverses the effect, but if the pattern is repeated for long enough, it results in insulin resistance, type 2 diabetes, heart disease and obesity. Professor Lustig believes that it is not possible for most people to quit through willpower because that has been eroded by the cycle of craving.

My mother’s switch from nicotine to sugar made Lustig’s narrative especially compelling for me: she simply replaced one addiction with another. And it chimed with my own experience. Battling exhaustion after my third child, and sitting opposite a fellow columnist who practically mainlined Coca-Cola, I fell into the habit of needing a Coke and chocolate bar before every deadline. Since I was filing copy almost everyday, as a Times leader writer, my consumption of sugar was considerable. And pretty soon the chocolate bar was no longer a single small, elegant Green & Black’s, but a string of Yorkie bars.

This kind of ‘mindless eating’ has been brought to life, hilariously and poignantly, in experiments by Brian Wansink of Cornell University. In one, he gave stale popcorn to two groups of cinema-goers. One group got big buckets, the other got giant buckets so large that researchers assumed no one would finish them. When the movie ended, the people with giant buckets had scoured them clean– they’d consumed 50 per cent more popcorn than the others. When told this, most were astonished.

For decades, we were warned off saturated fat. A profitable industry grew up selling ‘low-fat’ processed foods. But these are a con. To make them tasty, manufacturers stuff them with carbohydrates and sugar. These create spikes in blood-sugar levels, which lead to cravings when blood sugar falls, along with the brain’s chemical messenger, dopamine. Dopamine gives pleasure, but also regulates our self-control. So Big Food offering low-fat cakes is the equivalent of Big Tobacco offering low-tar cigarettes: they make us feel better about ourselves, while keeping us hooked.

I hope that doesn’t sound hysterical. In 2015, there was a mortifying moment when I was called a ‘health fascist’ by one of the prime minister’s other advisers. We had just come out of his office in Downing Street, where I had been arguing that we should tax sugary drinks. I was taken aback to hear myself described as fascist. But I believed we could no longer rely on exhortation to stem the obesity epidemic–we needed manufacturers to change their ingredients.

In 2016, the UK government announced that it would levy a tax on sugary drinks to tackle obesity. By the time the levy came into force two years later, most brands had already done what we had hoped they would: reformulate to avoid the tax, thus withdrawing substantial amounts of sugar from the supermarket shelves. While a few customers have complained about taste– and Coca-Cola has refused to dilute its legendary Classic– many are switching to low-sugar products. This suggests that relatively small signals can change markets.

Reformulating food is much more complicated for the obvious reason that processed foods contain far more ingredients than drinks (if you remove all the sugar from a cake, it will simply collapse and look like a soufflé). But the UK government has already had some success in working with manufacturers to remove salt from processed foods. The same could be done for sugar—with the right combination of goodwill and political drive.

The assault on cigarettes was only partially about taxing and making them more expensive. It also involved health warnings on packets and restrictions on advertising. We need clear, unequivocal health warning on processed food and drink in a universal language, not complex labels in small print that few of us can make sense of–especially when we’re rushing down a supermarket aisle, vulnerable to pester power. One doctor recently told me that the government should be focusing on parents and grandparents, not child obesity.‘ Unless the parents and grandparents lose weight,’ she said, ‘we’ve got no chance with the children.’

Parents and grandparents may not trust government, or the media, to tell them what to do. But they do trust doctors.

Text from Extra Time: 10 Lessons for an Aging World by Camilla Cavendish, published by HarperCollins

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