"Before the diet mania, the average American woman
took in 3,000 to 5,000 calories a day; today that average woman eats
less than 1,600 calories daily and is on some type of weight loss
program,"

It fails to mention an additional factor: various conveniences has made it
such that the average person is a lot more sedentary now than they were in
the past. i.e., 3000 to 5000 calories a day in the past was a lot less
'damaging' that it is now.