Caslon said"...new research suggests that the body is not so easily fooled, and that sugar substitutes are no key to weight loss — perhaps helping to explain why, despite a plethora of low-calorie food and drink, Americans are heavier than ever."
Americans are heavier than ever as they have a super sized diet coke along with their supersized diet meal nothing more nothing less.
Whilst their maybe truth in the matter of the body preparing for a high energy release from sweet carbohydrates I doubt it would slow the metabolism down by any noticeable level, the volume required to do so is more than likely to be offset by the diaorea as a result of the substantialy increased amount of phenylalanine!!!!
I got sent a link to the research today tho so havent had chance to read through it all yet but have only seen the highlights and it just reads as propaganda within the food industry yet again!