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Any analysis like this is truly informative only if all the variables are controlled for other than the one being studied, which the scientists didn't do. For example, I don't see how just looking at longevity figures is very helpful at all; obviously, an industrialized country where people are not periodically subject to famine conditions, live and eat in sanitary conditions, are immunized against many infectious diseases, etc. etc., are going to live longer. So, the comparisons that might be more helpful would be ones that compared all the industrialized nations to one another.
Also, in computing these longevity figures, the researchers are, of course, including cancer deaths...but so many cancer deaths can be attributable to smoking and those rates vary by country, so perhaps that variable should be controlled for as well.
The most obvious failing, to me, is the fact that they didn't consider that different types of protein might have a different effect. The proteins consumed in northern Europe, and eastern Europe, in particular, are animal proteins which are normally very high in fat. The Japanese consume mostly plant and fish protein. There may be other differences between these various types of protein than just fat levels, as well, differences and effects that we don't yet understand. What would be interesting would be a comparison of longevity and the consumption of various *types* or proteins, or longevity in terms of animal fat consumption.
I agree that *in general*,it seems that thinner people with a normal BMI live longer than obese or even slightly overweight people. Why the people in certain countries are more obese than others surely does depend on diet, although there are, once again, other variables, such as level of physical activity (how much walking do people do, for example), alcohol consumption, and just simple self-respect, to be unkind.
Genetic factors also impact these levels, I think. Just generally, I think that throughout human history people have been on the verge of extinction for lack of food. People who stored fat for the lean times would be more likely to leave offspring. That's no longer an adaptive trait. Diets also developed in certain parts of the world that were once adaptive, but no long are...it may be necessary, when trying to farm in cold countries, to eat a lot of high fat foods, but when people live and work in centrally heated spaces, and the most exercise they get is going to the refrigerator to get a snack, the diet is no longer optimal for health.
Ethnic influences have a part to play as well. Look at the North American Indians, who have terrible problems with Type II diabetes from eating a European diet...or the Polynesians. I do not, however, think that because we spent so much of our history as humans as hunter-gatherers, and some Europeans, for example, might have twenty-thirty percent more of this ancestry, that this means that a high animal fat diet is healthy for anyone. For one thing, much of the recent research into the diet of the hunter-gatherers shows that they had a much more varied diet than the stereotype might indicate...studies on the high proportion of total calories from nuts, fruits, honey, etc. depending on the area. Second, a very large percentage of their protein intake came from fish and the fats from fish are very different from the fats from meat. Third, much of the game, although not all, that they hunted was very lean indeed. It bore no comparison to the grain fed beef, for example, so popular today in certain parts of the world. (And deservedly so...I can think of few things more delicious than a well marbled Porterhouse Steak!)
However, looking at the data per country within the subset of the industrialized nations for percentage of the population with "normal" BMI's, I didn't see the correlation between obesity and animal fat intake that I expected to see, at least not perfectly. Longevity, the prevalence of certain diseases etc., might be a different matter.
Great Britain 33
Croatia 35.4
U.S. 35.7
New Zealand 36.1
Ireland 42.4
Portugal 44.0
Spain 44.9
Poland 45.6
Slovakia 48.6
Lithuania 48.6
Norway 51
Sweden 52
Italy 52.6
Finland 52.7
France 53.5
Romania 55.2
Denmark 55.3
Austria 56
China 58.9
Japan 68.9
Also, although I know people who are on it, and who lose weight on it, I've never heard that the Atkins diet is recommended by nutritionists or physicians. Quite the contrary in fact. They usually seem to recommend something like weight watchers, which, from what I can see, is just a well rounded diet with a calorie ceiling. Or, as my Dad used to say...just push yourself back from the table!
Non si fa il proprio dovere perchè qualcuno ci dica grazie, lo si fa per principio, per se stessi, per la propria dignità. Oriana Fallaci