Time to end the war against saturated fat?

I'm partial to this explanation:

http://www.mprize.org/blogs/archives/2010/01/hi_dr_feinman_a...

>What I think we're seeing is exactly the divergence within these populations that you know: that carb is really rather bad for overweight, insulin-sensitive people, such that replacing it even with SFA is relatively harmless -- whereas for lean, insulin-sensitive people, SFA (and dietary cholesterol, its fellow-traveller in omnivorous diets) is likely more relatively harmful, because carb is less able to derange the metabolism. We have to remember that any time we look at these studies and see only modest or borderline-significant effects: 66% of the US population is overweight, and half of that majority is obeese; Europe is somewhat better-off, at 49.8% and 13.3% in men and 36.0 & 13.5% in women per MONICA. So the deleterious effects of any nutrient with a differential effect on low-BMI, insulin-sensitive people will tend to be blunted by the much larger number of people for whom such effects are blunted by their "larger" problem.

>It also means that the deleterious effects of a rise in SFA intake are at least temporarily outweighed if it is is part of a dietary shift into a lower-carb diet when it is successfully used for weight loss (as opposed to just being a person's self-selected default diet, which of course is what's going on in teh studies in Jakobsen and in the Swedish, Greek, and US Nurses low-carb/high-protein studies). But it's reasonably clear that if you're insulin-sensitive -- which, interestingly, is what one is likely to become after losing weight on a successful low-carb weight-loss diet! -- the effects of SFA become more relatively harmful as teh deleterious effects of carb recede.

>t the end of the day, we have to go with what we've got. Until we get a couple of thousand healthy twenty-year-olds locked up in metabolic wards for sixty years or so for a really vigorous diet trial, I think saturated fat AND carbs (especially starchy carbs) stand out as things to reduce in the diet, in exchange for vegetables, fruit, lean protein, and PUFA (and probably MUFA) as things to maintain or increase. And most people should lose weight!

One interesting question that I do not know the answer to is the kinetics of metabolism for different macronutrients. How quickly can our bodies metabolize fat, protein, and carbohydrates? Is it possible that our bodies convert carbohydrates into energy very quickly, thus leading to an excess of energy that gets stored as fat? While other nutrients get digested much more slowly and only used if needed?

The basic question is do all ingested calories get used? Does the body have a mechanism for maintaining a certain "ideal" weight that can function across a range of caloric intakes?

Different foods make you eat more or less, by eg filling you up faster or keeper you satiated (and satisfied) for shorter or longer. So if you want to test your hypothesis, you'd have to carefully control for these effects, in order to rule out that caloric input is king. (I.e. my null hypothesis here is that caloric input is what counts in the end, but different foods have an influence on how many calories you actually consume.)

Anyway, the caloric surplus was just a simple example. Perhaps a clearer example would have been `trying to gain weight through fasting'.

Yes, climate does change, for sure, and it's probably bad - but so many of the climate scientists were wrong in their predictions from 30 years ago, that they need to do more to be convincing with their predictions for 30 years from now. And the data crunching they are doing, every time I looked at it, is not convincing.