First off I'll admit that nutrition science is something I know very little about, but it seems to me that you're veering towards making the same sort of mistake you're claiming the people giving nutrition advice made in the '80s. They blamed fat for obesity, you blame carbohydrates, but the picture is probably more complex.
While trying to check some other claims you made in this thread, I found a comparison of how much fat and sugar different countries eat. The article where found the statistics made the point that Germans eat considerably more fat per capita then Americans, yet they are below the average in the OECD for obesity. This would seem to support your point about fat, but it made me do a bit more checking.
Another thing Germans consume more of than Americans is carbohydrates. They have a high fat/high carbohydrate diet... and yet they're thinner than Americans. I don't know what to make of this exactly, except that this is clearly complex, and statements like
quote:Some of the negative health effects of low-fat/high-carbohydrate diets are very visible, like obesity,
Americans' consumption of carbohydrates and rates of obesity both increased dramatically in concert. The currently ongoing change of emphasis from low-fat to low-carbohydrate diets is a direct reaction to this fact. There's no doubt here.
On the contrary, there seems to be considerable doubt. It seems you are correct that carbohydrate consumption was increasing while the obesity rate was increasing, but that was hardly the only change going on. Sugar consumption increased dramatically; the types of carbohydrates changed - with a huge increase in consumption of refined carbohydrates; the proportion of fibre in the diet went down; and probably most significantly, the total caloric intake went up.
Absolutely the picture is much more complex than just carbohydrates. The point I'm making isn't that only carbohydrates are to blame for obesity, because that's not even true, but that past government and mainstream dietary advice about fat and carbohydrates are to blame for the obesity/diabetes/heart-disease epidemic of the last half century and more.
Along with rising carbohydrate and sugar consumption, Americans have also eaten a lot more fat since the 70s (and more protein). I'm not sure you can blame government advice when people were clearly not listening to it, since they did not eat less fat.
I've copied in below a graph from a 2004 study in the American Journal of Clinical Nutrition. The dotted line along the top tracks carbohydrate consumption over the 20th century. Note that it's the same at the beginning as at the end. I'm unaware of any obesity and diabetes epidemic at the turn of the 20th century.
The bars underneath track fibre consumption. That, as you can see, has plummeted, and this is probably a big part of the problem. Did government advice ever really consist of 'stop eating whole grains and consume a lot more refined corn syrup?'