Robert Lustig explains why diet soda doesn't help with weight loss. Artificial sweeteners trigger an insulin response through a tongue-to-brain-to-pancreas signal, even without calories, which can lead to weight gain rather than loss.
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When you have, you take Diet Coke, while Diet Coke doesn't have or Diet Pepsi, we don't want to pick on any brand. But when you have these artificial sweeteners, although it's not sugar, you are triggering your insulin.
Exactly. When you put something sweet on the tongue, message goes tongue to brain, sugar is coming. Brain to pancreas, sugar is coming. Release the insulin. And so even though that diet sweetener did not have calories, even though that diet sweetener did not have fructose, you still trigger an insulin response. And when that happens, you're still going to end up with weight gain. And this is one of the reasons why there are no studies that demonstrate that switching to diet sweeteners leads to weight loss. Right.