Coffee is flavoured water.... it doesn't do ANYTHING for weight loss, it is all psychological.
Not one scientific report proving it works, in fact not even one scientific report.... cos they know it'll be a waste of money .... do you with companies spending $Billions on research and looking at atomic levels of proteins to try and find an easy slimming technique they'd have at least first spent a few quid to look at coffe?
People's weight goes up and down, mine can fluctuate a stone a year. Do these people have a baseline who say they lost weight? That would be their weight recorded daily over a few months, not the staring weight.
Like the Docs favourite 'magic' water, it's all in the mind
