Well…if its not metabolism then what is it? Could it be medication? We might be taking more meds as we get older, so could that be to blame? or do we just get lazier as we get older and not burning it off like we did?
Prof Tom Sanders, from King’s College London, said: "Interestingly, they found very little differences in total energy expenditure between early adult life and middle age - a time when most adults in developed countries put on weight.
“These findings would support the view that the obesity epidemic is fuelled by excess food energy intake and not a decline in energy expenditure.”
Dr Soren Brage, from the University of Cambridge, said the total amount of energy used had been “notoriously difficult to measure”.
“We urgently need to turn our attention not only to the global energy crisis defined by the burning of fossil fuels but also the energy crisis that is caused by not burning enough calories in our own bodies.”