"We studied 15 428 adults aged 45–64 years, in four US communities, who completed a dietary questionnaire . . . "
So obviously 100% accurate then. I know that when in the past I've discussed what I eat with doctors there has been a suggestion that the only way to accurately monitor what you eat is to weigh everything and I have done that for certain periods of time. Not something I wanted to do for ever, but a worthwhile exercise in showing just how wrong you can be when estimating food consumption.
And another thing:
". . . . who did not report extreme caloric intake (<600 kcal or >4200 kcal per day for men and <500 kcal or >3600 kcal per day for women)."
Even if I was exercising a lot more than I do, I would only be on about 2700 calories a day. How come they didn't consider caloric intake extreme until it went over 4200 cals per day for men.