The New Paleo Diet Study: Just the Fats Ma'am

A Palaeolithic-type diet causes strong tissue-specific effects on ectopic fat deposition in obese postmenopausal women

I don't know that this study is worth three posts -- grin -- but I decided to break it up anyway.  I blogged on the diet itself here, and the weight loss here.  This post will address the impact on ectopic fat.  So first, I want to mention the "misleading title" peeves.  Ectopic fat is defined in the abstract:

Ectopic fat accumulation in liver and skeletal muscle may be an essential link between abdominal obesity, insulin resistance and increased risk of cardiovascular disease after menopause.

Here's the relevant synopsis of the results:

Liver triglyceride levels decreased by 49% whereas IMCL [intramyocellular lipid] levels in skeletal muscle were not significantly altered.

Which apparently garnered the conclusion:

A modified Palaeolithic-type diet has strong and tissue-specific effects on ectopic lipid deposition in postmenopausal women.

Rather than "tissue-specific effects on ectopic fat deposition" this title should have just stated "hepatic triglycerides" or something like that.  I also believe that a the caloric reduction and/or weight loss should have been "credited" in the title, if you're going to credit anything using the *causes* word.   They saw a large effect in liver fat.  Say so!  Furthermore, they saw reduction of existing fat while the title gives the impression that the "paleo diet" alters fat deposition patterns.  So this wording is awkward.

Without a control group, there is no justification for the words "causes" or "effects".  There was fairly significant weight loss -- about 10 lbs average -- in a relatively short time -- 5 weeks.  This weight loss alone, irrespective of diet composition, may well have been the cause of the reduction in liver fat observed.   That's what I tend to believe based on the various and sundry studies that have demonstrated reductions in liver fat with weight loss, especially fairly rapid, short term losses.

So here are the ectopic fat results:

Intramyocellular lipid to water ratios:

Tibialis ant:

• before:   Q1= 51   , Median= 93   ,   Q3= 166
• after:     Q1= 100 ,  Median= 114 ,  Q3= 173

Soleus

• before:  Q1= 187  ,  Median= 343  ,  Q3= 573
• after:     Q1= 243  ,  Median= 560 ,  Q3= 795

Hepatic Fat/Water Ratios:
{values estimated from plot}

Q1= 1.5 , Median= 8.0 , Q3= 10
Q1= 0.5 , Median= 1.5 , Q3= 8.0

It would be interesting to have plots like the one at right for the muscle fat, weight changes and change in caloric intake for the individuals.   As it looks like the IMCL trended upwards if not statistically significant.  This may not be a bad thing, but this was a pretty low carb diet so one might expect a bit more "fat burning" going on and IMCL "local stores" to increase a bit (as they do in trained endurance athletes).  This might also account for differences in both weight and fat loss between LC and HC diets as lipid stores shift slightly to lean tissue with less associated intercellular water mass (see the two related posts here).

But I won't speculate more on the muscle lipids since we have no individual data. The liver fat is quite interesting but I'm glad they gave the individual data as the 49% reduction (in the mean) is somewhat misleading in both negative and positive ways.  Looking at the plots we learn:

• 40% of the women didn't have significant liver fat to begin with.  Thus not all overweight/obesity is associated with fatty liver as some tend to portray.
• Of those with low starting lipid content, there is negligible loss of liver lipids. This is as to be expected. 
• The two women with really fatty livers lost substantial liver fat! While the content didn't go down to "normal", the reduction was greater than the 49% mean.  Another way to put it, is that the mean reduction in liver fat for the 60% with fat to lose, the loss was likely around 100%.  
• One individual gained liver fat (doubtful it is significant) on paleo.  That's just one, but that is 10% and I'd love to know the intake and weight changes for this person.  

So basically, without any control group we have no evidence that diet composition impacted the ectopic fat.  If anything, the IMCL increased on the 40% fat diet which may have been the reason why whole body insulin sensitivity didn't improve.  But this study does demonstrate that if you "drain the swamp", with a dramatic reduction in intake (25% average) and lose a bunch of weight (10 lbs) relatively quickly (5weeks, 2lb/wk), you stand a good chance of reducing your liver fat substantially if you have any accumulated there in the first place.  My speculation is that the IMCL response may have differed with diet composition, but the hepatic fat "drain" is probably more of a function of the caloric deficit than composition.

There have been some discussions on sat fats and fatty liver that I will try to get to.  If folks could repost the links here I'd greatly appreciate it.

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Eades Fact Check:

I was also reminded in comments on the last post of the confusion the Eades are partly responsible for in some ways about types of fat, etc.

In 2009 I purchased their 6 Week Cure for the Middle Aged Middle because I still thought Eades actually had a clue about nutritional science at the time.  I was promised research would back up their diet to specifically reduce belly fat.  

The first two weeks of this plan (low carb SlimFast = shakes and 1 meat and LC veggie meal) were for detoxifying your liver.  They presented a hodge podge of studies to reduce "visceral fat" that were actually studies -- like this one -- showing losses in liver fat.  Now visceral fat is adipose tissue surrounding our internal organs, within our abdominal cavity under the muscle wall.  Liver fat is fat in the organ itself.  To be fair, it is often included in the general term visceral fat, but these are different things.  If I have liver fat, and lose it, it's likely not altering my waistline.  It's not "belly fat".  (I note that Eades advises you to give blood after this phase to rid yourself of toxins -- and give them to others, but don't worry about that as you aren't really doing that somehow.  If you don't, they'll just find their way back into your liver!)  

In any case, hepatic fat, that might interfere with liver function, and visceral adipose tissue, which is considered more "metabolically active", are two different things. Circulating free fatty acids (FFA or NEFA) are largely regulated by release from upper body fat.  If you have a lot of visceral fat you have a "beer belly" (NOT a wheat belly!  LOL) that protrudes but is relatively hard.  If you have a lot of subQ belly fat you have the "muffin top", the "pannus", the "belly roll", the "Michelen Man" look, etc.  There is evidence that this is less harmful and/or associated with risk than visceral fat, but there is a TON of confusion and conflict to be found in this regard vis a vis the type of abdominal fat.  So sorry Dr. Lustig, you aren't entirely off the hook if you just have excess glucose induced subcutaneous adiposity.

In the end, if you take to this version of LC, you'll lose weight and some of it will come off your belly. There's no magic "targeting" backed by credible science to be had here.