There’s a simple idea that’s hidden in a lot of health advice: cut back on sweets and you won’t want them as much. Cut back on the sugar, clear your palate, and stop the cycle. That makes sense. A new study from Bournemouth University and Wageningen University says it’s also almost certainly wrong.
The study, which was published in the American Journal of Clinical Nutrition, followed 180 people for six months. Researchers put them into three groups: one ate a lot of sweet foods, one ate a lot less, and the third ate about the same amount of sweet foods as the other two. Each group was checked at one, three, and six months to see if their taste preferences, body weight, and a number of biochemical markers linked to heart health and diabetes risk had changed. As a result? On almost all of the measures, there were no differences between the groups.
People who ate more sweet foods for six months didn’t feel like they wanted sweets more. People who cut back on sugar for six months also didn’t have less of an appetite for sweets when they came back. When the study was over, the people who took part almost immediately went back to eating the way they did before, as if the whole intervention had not even occurred to them.
There is more to that finding than meets the eye at first glance. Katherine Appleton, a psychology professor at Bournemouth University and the study’s lead author, put it simply: what’s in the food, not how sweet it tastes, is what matters. Sweetness and sugar are not the same thing, and mixing them up in nutrition advice could be really bad for people’s understanding of nutrition.
That difference should be thot about for a moment because it changes a lot of common sense. When a mango is ripe, it tastes very sweet. It has fiber, vitamins, and other nutrients, as well as naturally occurring sugars. A fast-food burger bun might not taste sweet at all, but the dough inside can have a lot of sugar that you might not expect. Telling people to stay away from the mango while they quietly eat the burger bun is not only useless, it could even be harmful.
The World Health Organization currently says that people should limit their daily free sugar intake to less than 10% of their total daily energy. They say that dropping it to 5% would be even better. That is a reasonable goal, and there is strong evidence that eating a lot of sugar can cause cavities, weight gain, and heart problems. What is less clear is the separate WHO suggestion that people might be able to cut down on their sugar intake if they are exposed to less sweetness. This is true whether the sweetness comes from sugar, natural sources, or low-calorie sweeteners. The sugar diet research from Bournemouth University now gives the skeptical side of that debate a lot more weight.
It’s not that Appleton’s team doesn’t care about sugar. It certainly does. This is what they are fighting against: the idea that sweetness itself is the problem that needs to be fixed. Fruit tastes good. It’s nice and sweet. Diabetes and obesity are not caused by either of these things. A lot more likely culprits are processed foods that are high in calories and fats and sugars that are added. These foods don’t always taste sweet.
Another lesson is that public health messages get easier to understand until the easier language starts to mislead people. The phrase “eat less sweet food” is clean, easy to remember, and, as you can see, not very helpful.”Eat less high-energy foods and watch how much sugar you eat” is harder to put on a poster, but it’s more in line with what science says.
It’s still not clear how this study will change the official food guidelines, which change slowly. But the sugar diet study from Bournemouth University is part of a growing body of work that consistently finds little evidence for the palate-reset theory. This includes earlier studies from the same team. At some point, it gets hard to ignore that consistency.
