Artificial sweeteners can’t fool your subconscious brain


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Here’s a mystery: Why is obesity still such a problem in the age of the magic zero-calorie sweetener? New Scientist has a great article on the latest brain-scanning research, which offers some hints about how these sweeteners may fool us on a conscious level, but don’t manage to trick our unconscious minds. These new studies suggest that “zero-calorie” options may really just lead to “deferred calories” that make us consume more than a full-sugar version would have.

For many years, there have been hints that people who drank sugar-free sodas ended up gaining more weight than those who didn’t. (Travis Saunders described some of this evidence at Obesity Panacea last year.) Guido Frank at the University of Colorado is one of the researchers whose studies help explain this. He fed drinks containing either sucrose (sugar) or sucralose (artificial sweetener) to subjects, who were unable to tell the difference between the two. However:

Sucrose produced stronger activation in the “reward” areas of the brain that light up in response to pleasurable activities such as eating and drinking. Sucralose didn’t activate these areas as strongly… Frank suggests that sucralose activates brain areas that register pleasant taste, but not strongly enough to cause satiation. “That might drive you to eat something sweet or something calorific later on,” he says.

This is still a developing area of research, but it seems highly likely that there’s no (calorie-)free lunch. You can’t have sweetness without (eventually) paying a caloric cost.

The obvious question, then, is whether you’re better off drinking diet soda or full-sugar soda. I’ll join with Travis Saunders in suggesting that you keep consumption of either to a minimum (though, as with most “bad” foods, it should be fine in moderation). But if I’m choosing between the two, now that I know that the overall caloric hit will be about the same for regular and diet soda, I’d rather drink the real thing.

[Thanks to Selam for the tip!]

2 Replies to “Artificial sweeteners can’t fool your subconscious brain”

  1. The New Scientist article is very interesting. I’m still on the fence about diet sweeteners, but Yoni Freedhoff of Weighty Matters ( is not – he feels very strongly that diet sweeteners are useful for weight loss in the obese patients he works with. Here are his previous thoughts on the issue:

    What’s interesting is that these more “pure” studies seem to suggest that diet drinks could lead to overconsumption, but more applied studies in obese populations seem to suggest that diet sweeteners can help with weight loss, at least when compared to regular soda. I spoke with an endocrinologist named Bob Lustig last summer who has done a lot of work with fructose and other sweeteners, and he said that on a scale of 1 to 10, with water being 0, and coke being 10, he’d put diet soda around a 7. I think that’s probably a good way to look at diet sweeteners – better than full calorie sweeteners, but not as good as water.

    I think Yoni is planning to add more on this subject on his blog in the near future, I’d be curious to see what you think of his next comments.

    As usual, terrific post!


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