In the article "The Overflowing American Dinner Plate", Bill Marsh cites USDA data showing a 59% increase in fat consumption from 1970 to 2006, coinciding with the doubling of the obesity rate in America. However, according to Centers for Disease Control NHANES nutrition survey data, total fat intake in the US has remained relatively constant since 1971, and has actually decreased as a percentage of calories. The apparent discrepancy disappears when we understand that the USDA data Marsh cites are not comprehensive. They do not include the fat contained in milk and meat, which have been steadily decreasing since 1970.
The change Marsh reported refers primarily to the increasing use of industrially processed vegetable oils such as soybean oil. These have gradually replaced animal fats in our diet over the last 30 years. Since overall fat intake has changed little since the 1970s, it cannot be blamed for rising obesity.
I wrote a letter to the New York Times about their recent article "The Overflowing American Dinnerplate", which I reviewed here. The letter didn't get accepted, so I will publish it here: