- one can design a study that will "prove" anything one bloody well pleases;
- the proclaimers get all nearsighted when accosted with a study that "proves" the opposite;
- just because it works on genetically-modified mice does not mean it will apply to humans;
- due to genetic and time/damage-wrought variations in humans, we can each react very differently to ANY stimulus.
...Because ideal macronutrient ratios are different between rats and mice, let alone us.
...Because studies often use human subjects who are young, whole, and uncomplicated -- not the middle-aged, menopausal and carbohydrate-intolerant.
...Because the sometimes-arbitrary conditions of laboratory studies don't necessarily match real-world situations.
"Science" can be very good at pinning down mechanisms and processes once they're identified, but until they are, conducting studies can just confuse the poor myopic plodders who do things like feed, exercise and test nocturnal animals during the daytime.
So -- sorry -- claims of scientific evidence are not a clinching argument, but rather a starting point for enquiry into ways and means. You may feel your study is definitive, but until you can show that it works in real people under normal circumstances, it doesn't actually MEAN diddly-squat.