Notwithstanding the "fat-free everything" fad, the best epidermiological data we have so far suggest that fat consumption is highly correlated with coronary heart disease and all sorts of late-life complications. This could be wrong or out-dated, but FDA is only acting on the mainsteam scientific opinion that fat should be limited in a typical diet.

http://onlinelibrary.wiley.com/o/cochrane/clcentral/articles...

USDA, on the other hand, has been deeply troubled by the public's distaste of fat as they have an obligation is keep dairy farmers afloat. To this day they have been trying all sorts of things to promote fat consumption without much thought to the health consequences. South Park touched on the subject in the episode "Gluten Free Ebola", but I guess most people missed that point. New York Times have done a good article explaining the economic and politics between the FDA-USDA feud.

http://www.nytimes.com/2010/11/07/us/07fat.html

Finally, one must note that individual idiosyncracies play a major role in how we respond to external inputs such as diets, exercise and medication. I am glad that paleo diet worked out for you, however please bear in mind that it may and may not work for everyone when you push it.

As from the article quoted: "dietary intake at total and saturated fat"

I wanted to see a study comparing the average fat intake of Paleo practitioners with the target of that study.

Oh by the way, trans fats are poly-insaturated (good for you! - and sold as such). Until it wasn't.

I'd love to see a study like that as well. And you're right, not all trans fats are bad. There’s a good trans-fat called conjugated linoleic acid (CLA) that is mainly found in meat and dairy from pastured ruminants. Grass-fed cattle produce 500% more CLA than grain-fed [2]. Only man-made industrial trans-fats are bad.

[1]: http://chriskresser.com/can-some-trans-fats-be-healthy

[2]: http://www.journalofanimalscience.org/content/78/11/2849.ful...

> Notwithstanding the "fat-free everything" fad, the best epidermiological data we have so far suggest that fat consumption is highly correlated with coronary heart disease and all sorts of late-life complications. This could be wrong or out-dated, but FDA is only acting on the mainsteam scientific opinion that fat should be limited in a typical diet

Yet if we look at other peoples and cultures around the world we can find several with high fat diets without the coronary heart disease and other problems that seem to plague high fat consuming Americans. Some examples are the natives of many South Pacific islands, the Inuits, and the Maasai.

Components of a diet do not act in isolation. It really has to be looked at as a complete system. If reducing fat in the American diet reduces coronary heart disease, that does not mean fat is bad or fat is causing coronary heart disease. It could be that if some one component instead of fat were removed the same reduction in coronary heart disease might occur (carbohydrates might be a good candidate, since the traditional high fat Inuit diet was very low in them, and they have much lower coronary heart disease than mainstream Americans do).

For nearly every rule, supposedly backed by the then current science when the rule was published, it is usually possible to find some place where the traditional diet breaks that rule yet the people there are doing fine, not suffering from the afflictions we've been told will befall is if we violate the rule.

The tendency to look at things in isolation doesn't just show up in unjustly declaring particular things bad. It also sometimes declares things good without sufficient justification. People look at, say, traditional Mediterranean diets and see that they have good outcomes, and figure it must be due to their heavy use of, say, olive oil. So then they start slathering olive oil over everything and expect they are going to get healthy no matter how crappy the stuff they are drowning in olive oil. In reality, there is probably no magic ingredient in the Mediterranean diets...it is the totality of their diet that is good.

What should be a simple task--regularly eating in a healthy way--is ridiculously complicated and requires way more research than it should in the US. And that's without getting into processed foods, and how the goals of processed food providers don't necessarily align with the goals of those trying to eat healthy.

I read somewhere (don't remember where, so can't give a good cite) that biochemists say we only understand about 10% of the chemical processes in our bodies. We know some things various nutrients are used for, but there are many we don't know. We often don't understand exactly how particular nutrients go from being part of our food to being being available at the places they are used in a form usable to our cells.

So it looks like the only reasonably effective way to eat healthy is to find some group of people whose traditional diet is known, and who have or had good outcomes in the health areas you are interested in, and had those good outcomes for a long time, and eat like you are one of them.

What I've not seen discussed is whether or not you can mix different diets this way. For instance, if you like the outcomes of traditional Mediterranean culture diets, and the outcome of traditional South Pacific Island diets, and so on for several cultures and their traditional diets, should you expect good outcomes if one day you eat like a South Pacific islander, and the next day like someone from a Mediterranean culture, and so on? Or do you need to stick with each culture's diet for some kind of extended period?

>I read somewhere (don't remember where, so can't give a good cite) that biochemists say we only understand about 10% of the chemical processes in our bodies. We know some things various nutrients are used for, but there are many we don't know. We often don't understand exactly how particular nutrients go from being part of our food to being being available at the places they are used in a form usable to our cells.

I think we know more far than 10% about our own biochemistry, but you are right in saying that there are plenty of processes we don't know enough about. Because the system is too great at adapting to changes that attempts to measure response from a single factor usually fails quite miserably. For example, Robert Lustig has been preaching for years that fructose is bad for you. His theory is scientifically sound, yet we have not observed the apocalyptic consequences he envisioned decades back. Similar debates on fat has been going on for decades and either side is backing up. Throw some economics and politics in there, and we have the mess we are dealing with today.

The main thing that set us apart from the indigenous peoples and perhaps our grandparents' generation is that we are feeding ourselves ad libitum which is very much unprecedented. After all, caloric restriction is the only proven way to enhance longevity in lab animals so it is quite likely that there is no magical diet but to eat and move as little as possible like the tortoise of Galapagos. Whether this lifestyle is conductive to a fulfiled life to open to (another) debate.

My son went from 320 to 210 in nine months while I went from 263 to 188 in the same amount of time so I can verify it certainly helps though overeating is possible on paleo, too.

However, I should note that we were working out in a gym three times a week and, after quitting that due to boredom and quitting paleo cause I love bread and ice cream, I went to 208 pretty quick.

So Paleo is not a cure all. Being a programmer who sits on his butt all day doesn't help at all.

I chronically under-exercise. I did so during that first year, I still do. My weight loss is explained by change in diet alone.