overfeeding study comparing palm (kernel?) oil and sunflower oil

by 4338 · March 28, 2014 at 10:45 AM

does anyone have full access to this study published last month, Overfeeding Polyunsaturated and Saturated Fat Causes Distinct Effects on Liver and Visceral Fat Accumulation in Humans.

Their conclusion was "overeating SFA promotes hepatic and visceral fat storage whereas excess energy from PUFA may instead promote lean tissue in healthy humans."

I would be interested to hear some comments.

here's the press link & first para, Abdominal fat accumulation prevented by unsaturated fat

"New research from Uppsala University shows that saturated fat builds more fat and less muscle than polyunsaturated fat.

This is the first study on humans to show that the fat composition of food not only influences cholesterol levels in the blood and the risk of cardiovascular disease but also determines where the fat will be stored in the body. The findings have recently been published in the American journal Diabetes."

Edit: I put 'kernel?' in brackets in the heading because i presume that they used palm kernel oil in this study & not palm fruit oil (red palm oil). In the abstract it is just referred to as palm oil, but since they were looking for a high sfa oil, kernel rather than fruit would make sense. May be it is defined better in the full text.

I'm sure (guessing really) that there are some confounding factors; like what happens to the oils when they are baked in the muffins. were the calories of the post baked muffins equal. did both groups gain equal amounts of weight. how processed were the oils. what would have happened if the study ran longer than seven weeks...

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3 Replies

4338 · March 28, 2014 at 10:25 AM

this article (link below) may shed some more light on why that study found that "overeating SFA promotes hepatic and visceral fat storage whereas excess energy from PUFA may instead promote lean tissue in healthy humans."

#1 Thigh and Buttock Fat Depots more Unsaturated than Abdominal Fat Depots

my guess would be that both groups gained weight, in the form of fat & probably some muscle as well (would need access to full study to confirm). But the 'sunflower oil' group added their (unsaturated) fats to their buts and thighs, rather than around their 'middle'. From the abstract, it looks like they did Not mri the study subjects buts & thighs, if that is true then they would have totally missed this fat deposition.

16813 · March 23, 2014 at 12:17 PM

We mostly store MUFA, then SFA, then, in smaller amounts, PUFAs.

http://ajcn.nutrition.org/content/74/5/585/T3.expansion.html (from

http://ajcn.nutrition.org/content/74/5/585.long ) It's possible that we're more likely to burn off unwanted PUFAs the same way as we'd burn off excess carbs by fidgeting, and store the types of fat we most likely find helpful for storage.

Now, that study was from obese folks, would have been nice to see the MUFA, SFA, PUFA breakdown similarly in fit, healthy folks in another study. If anyone has a pointer to such a table, that would be useful in figuring out what breakdown of fats are ideal for healthy humans to consume (if there are differences in the percentages.)...

That said, after several billion years of evolution, I highly doubt we'd store fat types in ratios that are harmful to us, so it's likely that our bodies has some way to sort the types of fat we eat and decides what to burn off and what to store based on need. We wouldn't want to store all MUFAs and SFAs, because those will become solid when it's freezing, so we'd need some PUFAs as protection against the cold, as well as for nerve tissues.

I'd imagine, we won't store (much?) oxidized PUFA as those are harmful to us and we'd need to eliminate them. After all, we don't store MCTs, we rapidly convert them into ketones and burn them off. So perhaps a similar mechanism for excess PUFA?

Of course, I question the definition of "high fat" in the paywalled study the question is asking about, after all, they overfed the subject with muffins - we're not told what kinds of carbs and how many are in the muffins in the abstract, vs how much fat. Certainly, high carb intake will trigger insulin, which will cause all macros to be stored, including the fats, and will certainly convert the carbs into fat. Gee, I wonder what kind of fats carbs convert into, I'll give you a hint, it isn't PUFA.

Interesting that the article is paywalled, yet at the bottom it says it's licensed under Creative Commons - would that mean that the full article is available somewhere else, or that it can be shared freely? A google of the title didn't return any free versions.

45 · March 22, 2014 at 03:37 AM

You can tell by the conclusion wording "SFA blah blah", that its not a objective study. Saturated fatty acids are all different. You can't generalize that stuff.

Same with their statement about cholesterol. Only some SFA's raise LDL in animal studies (not that this is the cause of heart disease, only a factor once the process of disease has begun already). Indeed some SFA's like coconut oil seem to raise HDL and not effect LDL at all.

Only really palmitic acid is the LDL raiser (from beef and dairy). And given the numbers of SFA

s, this "SFAs raise LDL" malarky, or even the notion that LDL is a central cause of heart disease when we know now that it is oxidation, and inflammation.

From this you can tell they are _loaded_ with bias coming into the study. You cannot trust such people, who generalize the ungeneralizable, and jump from association to causality, to actually come up with sound conclusions.

I reckon, presumably over eating PUFA doesn't result in as much fat storage because its harder to convert to useable energy. Although Id like to see the study, and question the visceral fat conclusion, because vegetable oils are like fructose and are heavily associated with NAFLD in other studies.

And I am never eating anything that pro-inflammatory, no matter how biased people are against saturated fat. I prefer not to get stroke and heart disease etc (and our brains clearly had to have evolved on sat fats and omega fats)

It would be interesting to see some of these less logical scientists think now an again.

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