Since 1980, most major dietary guidelines have recommend that we consume around 30% of our calories from fat. And, since then, this has become the gospel, even in many of the the vegetarian and vegan communities. Recently, some organizations, like the American Heart Association, has begun to recommend even higher levels of fat, in certain conditions.
But does anyone really know how and why they came to this recommendation? Is there conclusive evidence that this level of fat is optimal?
What many people do not realize, is that there was no good evidence for this recommendation and the 30% was a compromise and based on some relevant data that was "unrealistic" in reference to the USA.
The following quotes are from William P James , who is from the London School of Hygiene and Tropical Medicine, and the head of the International Obesity Task Force, which is part of the International Association for the Study of Obesity.
In a very recent article, The epidemiology of obesity: the size of the problem (Journal of Internal Medicine 263; 336–352). in relation to how they chose the recommended amount of fat in the USA, he says;
"They specified a 15–30% range in total fat intakes because the Chinese and Japanese, with negligible CHD, diabetes and obesity in the 1970s, were consuming on average 14% fat, but this was totally unrealistic for the US and Northern European populations where intakes were well over 40%. So to choose a 30% figure was radical and a response to the need to reduce saturated fat intakes by simply reducing total fat."
So, in other words, the SE Asia level of 14% (or less) was closer to the optimal, but because we were over 40% (around 45%), they looked at picking a level that was a half-way measure, and compromised at 30%. This was a compromise, not an ideal. The were hoping that by reducing total fat, they would also reduce the levels of saturated fat in the American diet, which was the main problem at the time.
However, this was not ideal as it did not take into account activity levels and the potential impact on a sedentary population.
From the same article..
"Ancel Keys’ Seven Country Study observations that fat might be related to the BMIs of his samples but not to CHD because the Greeks, on a high olive oil diet, had a low saturated fat intake at that time. The subjects also happened to be incredibly physically active: the selected shepherds in Crete were walking and climbing mountains all day long so this is hardly a realistic basis for suggesting that fat intakes do not matter."
They do matter. And, as consumption figures from the time indicate, the "high" olive oil intake at that time in Greece, was just under 3 TB a day. Their food was not "drenched" in olive oil. (Changes in food supply in Mediterranean countries from 1961 to 2001. Public Health Nutr. 2006 Aug;9(5):661-2.)
The Greeks around the 1960's were a rare example of a population that, although they had a higher fat intake, also had a lower saturated fat level, due to the type of fat they consumed. And, because they were "incredible physically active," they also managed to keep their weight down.
But to use this rare example of the diet of a country that is incredible active in the Mediterranean is "hardly a realistic basis for suggesting fat doesn't matter" for other populations. To apply it to a sedentary overweight population, like the USA, was incredible dangerous and we are now experiencing the resulting fallout.
My earlier article:
In Health Jeff