DR MICHAEL MOSLEY: Is fructose to blame for your love handles?

With the arrival of the winter days, I have developed a crazy urge to eat sugary, carb-heavy comfort foods.

This is clearly related to the days getting colder and shorter and me craving sugar to boost my mood, but it could also be caused by a subconscious fear of running out of calories during the winter months.

Despite all the temptations in the run-up to Christmas, I try to keep my sweet festive indulgence to a minimum, as I know this is the road to an expanding waistline and type 2 diabetes. Plus, there’s mounting evidence to support a new theory that a certain ingredient in sugar is a key factor driving our obesity crisis.

The idea that excess sugar can lead to weight gain is hardly new. But the stuff we call “table sugar” – the sweet white or brown stuff in your kitchen cupboard – is actually made of two sugars: glucose and fructose.

Unless they’re made with artificial sweeteners, most cakes, cookies and soft drinks you buy in Britain contain equal amounts of glucose and fructose (in the US, by contrast, you’re much more likely to find either that food or fructose). drink is sweetened with high-fructose corn syrup, which, as the name implies, tends to contain more fructose than glucose).

For a long time, fructose was seen as a ‘healthy’ sugar. But it turns out that when consumed in large quantities, it can have a dark side

For a long time, fructose was seen as a ‘healthy’ sugar. That’s because it’s the main sugar in fruit and doesn’t raise your blood sugar levels to the same extent as glucose. And that’s why people with diabetes are sometimes told to switch to using fructose as a sweetener.

But it turns out that fructose, at least when consumed in large quantities, may have a dark side.

This is what scientists from the Anschutz School of Medicine at the University of Colorado in the US say in an article published in the journal Obesity.

Based on their previous research into how fructose affects cells, they claim that fructose, unlike other sugars, causes our metabolism to go into what they call “an energy-saving mode.” This then leads to hunger and causes us to lose control of our appetite, so we eat more (not just sugary foods) despite having eaten enough.

Normally, your food is broken down and absorbed by your intestines, then converted into adenosine triphosphate (ATP) – a substance that every cell in your body uses as its main source of energy.

But scientists at the University of Colorado claim that if you consume too much fructose, it suppresses ATP production. And when ATP levels start to drop, your brain – worried that its energy supply is at risk – triggers hunger signals and tells you to eat more. What you do.

But because you now eat much more than your body needs, you become fatter.

Further evidence that fructose may play an important role in obesity comes from previous research, published in the prestigious scientific journal Nature, in 2019. In this study, researchers from New York-Presbyterian/Weill Cornell Medical Center divided mice into three groups: one group was given a low-fat diet; the second on a high-fat diet; and the third, a high-fat diet with added fructose.

The mice on a fructose diet consumed much more fat, despite consuming the same number of calories as the other groups. This was because their villi – the small finger-like projections that line the small intestine (in mice and humans) and help your body absorb the calories you eat – grew much longer.

The scientists suggested that the longer villi meant the mice’s bodies absorbed many more calories, making them fat.

Previous studies by the same team have also shown that feeding mice fructose stimulates the growth of other cells, increasing the risk of colorectal cancer.

When asked why consuming fructose would have these effects, the scientists suggested it may have been a winter survival strategy.

Before the days of widely available and mass-produced foods, fruit was the main source of fructose in the natural world. And most fruit becomes sweet and ripe during late summer and fall.

So from an evolutionary perspective, it makes sense that as your body tries to prepare you for the long winter months ahead, when food is scarce, eating fructose (in the form of fruit) will not only help you absorb more energy to lie down. it registers as fat, but it also helps to switch off your cells (by putting them in ‘low power mode’) so they burn less fuel.

What to keep in mind the next time you’re tempted to eat something sweet: It’s the fructrose that makes you want to eat more.

But while this can be a useful survival strategy if you’re a hibernating animal like a bear, it’s not at all useful in the modern age, when we can buy a pack of cookies or order a takeaway whenever we get a little peckish. .

The researchers involved in the Nature study were careful to emphasize that the problem does not come from eating high-fructose fruit, as it contains fiber (which is not only good for your gut, but also reduces sugar spikes) and other valuable plants. connections; it comes from the added sugars we consume every day.

As Dr. Marcus DaSilva Goncalves, an endocrinologist who led the study, put it: “Fructose is nearly ubiquitous in modern diets, whether it comes from high-fructose corn syrup, table sugar, or from natural foods like fruit. Fructose itself is not harmful, it is a problem of overconsumption.’

Something to keep in mind the next time you’re tempted by a sweet treat: it’s the fructose that makes you eat more.