The letter was triggered by a recently reported and heavily publicized study that suggested energy intake has decreased significantly since 2003-2004 - with an average reported decrease of 98 cals/day. The letter's authors note that the data used to come up with the exciting decrease has been shown to be flawed before, and moreover, that it would appear as if bias in reporting of energy intake may be increasing (perhaps due to increased attention and bias versus those with obesity). They also note that were it in fact true the population ought to have lost an average of nearly 8lbs since 2003.
Their final conclusion is firm and one I agree with in regard to studies designed to look at ways to prevent or treat obesity,
"Going forward we should accept that self reported energy intake is fatally flawed and we should stop publishing inaccurate and misleading energy intake data."[And for good measure, up above is another of my collection of photos of gigantic fruit - this time a 10oz plum bigger than an apple.]