The diet-heart hypothesis is the idea that saturated fat, and in some versions cholesterol, raises blood cholesterol and contributes to the risk of having a heart attack. To test this hypothesis, scientists have been studying the relationship between saturated fat consumption and heart attack risk for more than half a century. What have these studies found?

~ Stephan Guyenet from, The Dirty Little Secret of the Diet-Heart Hypothesis

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Body fat produces a hormone called leptin, which signals to the brain and other organs to decrease appetite, increase the metabolic rate and increase physical activity. More fat means more leptin, which then causes the extra fat to be burned. The little glitch is that some people become resistant to leptin, so that their brain doesn’t hear the fat tissue screaming that it’s already full. Leptin resistance nearly always accompanies obesity, because it’s a precondition of significant fat gain.

~ Stephan Guyenet from, The Body Fat Setpoint, Part II: Mechanisms of Fat Gain

This part of his series is short and non-technical. But his whole series is, probably, the greatest explanation of why one gets fat which I have ever read.

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The bottom line is that experimental models of atherosclerosis appear to rely on overloading herbivorous species with dietary cholesterol that they are not equipped to clear. SFA does exacerbate the increase in LDL caused by cholesterol overload. But in the absence of excess cholesterol, it does not necessarily raise LDL even in species ill-equipped to digest these types of fats. Dietary cholesterol has a modest effect on LDL cholesterol in humans, and it has even less effect on LDL particle number, a more important measure. So there may not be a cholesterol overload for saturated fat to exacerbate in humans.

~ Stephan Guyenet from, Animal Models of Atherosclerosis: LDL

In the context of actual amounts that you can actually consume (animal studies feed cholesterol to herbivores as if you eat 20+ eggs EVERY day) there is no evidence (not in animal studies and certainly not in human studeis) that cholesterol and saturated fat cause atherosclerosis. If you think eating cholesterol or saturated fat is bad, I hope you’ll investigate where you obtained that knowledge, and look into the factual basis of that knowledge. If you’re avoiding cholesterol and saturated fat, what are you replacing it with?

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Do whole grains prevent smoking too? An alternative explanation is that the women who were eating whole grains were all-around more conscientious and concerned about their health than those eating refined grains. And why not? They “knew” from mainstream diet advice that whole grains are healthier than refined grains. When is the last time you saw someone smoking a cigarette while eating whole grain muesli with skim milk and half a grapefruit for breakfast? Is it easier to imagine someone smoking while eating a donut and sweetened coffee?

~ Stephan Guyenet from, Modern Diet-Health Epidemiology: a Self-Fulfilling Prophecy? Part II

I recommend reading everything on the Whole Health Source blog; Very science-intensive, but you’re life will be imrpoved. And, the above piece is a great explanation of things like “correletion”, “confounding factors”, and more. But, there’s also a HUGELY useful take-away that he doesn’t explicitly state:

By being health-conscious — reading, learning, making small changes — you’re going to have a huge affect on your health. In the long run, you don’t need to learn every little scientific nuance (because who has time for that, right?) Instead, you learn a little each day and continuously work to make small improvements.

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