More on Water Weight & Insulin

There's an interesting related conversation on this topic going on over at Paul Jaminet's site:

Water Weight: Does It Change When Changing Diets? Does It Matter?

For those not familiar with the Perfect Health diet, one component is to get ~400 cal in "safe starches" -- around 100g.  For those transitioning to their diet from a low carb diet, some have experienced a not-unexpected weight gain.  I've added some thoughts to the comments there and -- can't be sure and some is just a hunch -- but I think any weight bounce is probably more carb associated, predominantly glycogen repletion.  It may well be due to replenishing other "carb" molecules with their associated water as well.  My guess is that for the most part these changes show up on the scale more than in dimensions.  That was my experience during the almost 3 years of my "low carb cheating" plan.  I can't know for sure for the first year and a half or so of that, because I never weighed, but I didn't gain size during my cheats (pants still fit fine) and later after I weighed I sometimes saw a few pound gain, but again this didn't effect the fit of the skinny-jeans much if at all.  

However my current interest/focus is building on this recent post of mine:

Insulin, Weight Loss & Water Weight

In that post I referenced two studies that I'll repeat link to here:

Changes in abdominal subcutaneous fat water content with rapid weight loss and long-term weight maintenance in abdominally obese men and women - This one discusses how following rapid weight loss and improvement in insulin sensitivity of the fat tissue, fat mass increases due to increased associated water resulting from improved blood flow.

Disparate Hydration  in Adipose and Lean Tissue Require a New Model for Body Water Distribution in Man.  This one discusses various models of determining total body water content, and the contribution of adipose tissue often ignored for lean populations.  It also discusses the extra and intracellular distribution of water in adipose tissue and lean tissue.

So, adipose tissue is approximately 75% lipid and 14% associated water of which 11% is extracellular (between the cells) and 3% is intracellular (within the cells).  The remaining mass is presumably relatively constant comprised of the cell walls, connective tissue, organelles, etc.  The ECW:ICW ratio is 3.5:1

Non-adipose tissue is approximately 79% water, and in papers I've read on intramyocellular lipids (IMCL), lipid comprises between 1% "normally" and 2% when "elevated".   This leaves the rest comprising roughly 20%.  Interestingly, although by all indications AT water distribution is similar in lean vs. obese, it varies for AFM (adipose free mass).  In lean ECW:ICW = 0.42 while for obese it ranged from 0.49 to 0.99 averaging 0.72.  The obese tend to have higher levels of IMCL, the ratio of ECW:ICW correlated with degree of obesity, so it seems that increased IMCL content results in a water shift from inside to outside of the non-adipose tissue cells.  I am not sure the implications of this, but perhaps we need not even really bother because the associated water weight was not significantly different.  IOW, even if we double the lipid content of the cells, the mass of AFM will remain fairly constant.

So, a little math.   

Let’s say you have 75 g lipid in your fat cells, this represents 100 g adipose tissue mass (lipid content is 75% of total fat mass), and of that 100 g AT, 14% is water (14 g), 11% being extracellular (11 g), 3% intracellular (3 g).   So:  75 g lipid is associated with 14 g water in adipose tissue.  Or for every gram lipid released from an adipocyte, you "lose" almost 1.2 g "total weight" and "fat mass".

If the lipid is oxidized we can assume the water is eventually excreted.  But with reduced insulin (as in that DZ study) more lipid is released.  That study showed, however, that more was not oxidized.  So, it was taken up by AFM where the associated water is inconsequential.  Now for every gram lipid released you retain that gram of lipid, but "lose" almost 0.2 g "water weight".  

How does this match up for DZ vs. placebo in that study?  Well I can't do a total mathematical analysis, but insulin reduction did lead to greater FA release with a concurrent "freebie" loss of ~20% of the released mass.  That wouldn't seem to explain double the weight loss, but perhaps the "dehydrating" of the non-adipose cells could also lead to more losses.  And I'm not at all sure we could measure IMCL and extrapolate that to total AFM lipid mass.  Lastly, the hyperinsulinemic placebo group may have seen increased water content in AT as insulin sensitivity improved.    I would note that for whatever reason, the "after" placebo insulin levels still exceeded the "before" DZ group levels, despite being reduced by approximately half the absolute amount achieved by DZ treatment.  What this means?  Dunno.

Yes, dear readers, lots of ifs and perhaps here.  But I'll leave you with this.  If someone is 100 lbs overweight, they probably have about 80 lbs excess fat.  Of the 80 lbs excess AT, that's 60 lbs "fat" and about 11 lbs water.  Hormones, like insulin, CAN and DO influence the distribution of lipid stores in our tissues.  Lower insulin and higher fat consumption and circulating FFA's do shift some stores from AT to AFM with a resulting loss of associated water weight.

So ... there you have it folks.  A non-metabolic advantage!

It remains to be seen (and herein lie my concerns) whether:

• A shift of lipid stores to ectopic (non-adipose) tissues is preferable, deleterious or innocuous
• The "dehydrated state" is preferable, deleterious or innocuous

And it does appear, based on the weight loss trajectories of long term studies as well as anecdotal evidence, that once weight loss has occurred and the body stabilizes over a period of months and years, if this repartitioning persists or re-adjusts.  Also, since I can take a diuretic pill and shed water weight in a matter of hours, how much does this impact our total body water content in the long haul?