Fasting Insulin & Weight Loss
Some folks have been having a bit of a go at me over at Peter/Hyperlipid's blog. I guess it all started by Peter taking some sort of offense to my post on his Potatoes and weight loss post entitled Insulin Caused Cerebral Stress. My intent with my post was not to mock Peter. It was to point out how so inconsistent with observations the carb/insulin hypothesis is, so as to elicit elaborate explanations such as the scenario Peter described to explain a simple phenomenon: Voight lost weight eating potatoes by estimating his energy needs and eating a controlled amount of predominantly potato-derived calories. Peter, himself, started that post discussing the time/pages he had spent developing his theory. I don't question/contest that what he says regarding insulin, sensitivity, etc. may actually be true. I do believe, however, it is irrelevant. I say that because I just do not see consistent evidence to support his assertion that:
My point was that, there was a much simpler explanation for why Voight lost weight: He expended more calories than he took in. Why? Well, likely because Voight monitored his intake. Perhaps he underestimated maintenance levels, maybe potatoes make him hyper and increase NEAT, maybe he has digestive issues and didn't absorb all his potato-derived calories. Who knows? But my premise is that:
The ultimate determinant of weight loss is being in energy deficit. ~Penelope Jones
Therefore when someone loses weight eating potatoes or cream cheese, Twinkies or beef & coconut oil, I do not have to do any mental gymnastics to "wrap my head around" the results. Whatever they did, purposefully or spontaneously, to ELMM resulted in being in energy deficit - made up for by feeding off energy stores ==> weight (fat) loss. Peter, however has been unapologetic about his insulin-centric bias (on his own blog, I'm not putting words in his mouth). As such, he has expressed a liking or disliking for certain studies, and/or surprise or disappointment for the results of others, based on whether they tend to support or refute his belief system.
So Peter referred to one of my recent posts here, Insulin, Weight & Fat Accumulation, in a post of his own entitled Gourmand Rats. In my post, I expanded on the work of Grey and Knipnis. This study looked at fasting insulin levels compared with body weight in some young obese women under maintenance level and fixed hypocaloric conditions. The results are shown below again.
The fasting insulin levels are all over the map, and yet the subjects either maintained or lost weight predictably. Before we get to Peter's analysis of G&K, I will address his Gourmand Rats post. He begins it with:
You know how it is when CarbSane quotes a paper which refutes the carbohydrate hypothesis of obesity. You really can't be *rsed to chase it but you also know that there will be a fundamentally flawed approach which needs looking at. CarbSane was my route in to Kathleen Axen's work with transfats, which I've probably not finished with yet, but which markedly ramped up my dislike of these industrial lipotoxins. I really enjoyed digging back through the Axen papers, though it took hours, and there's no way I would have hit on them without CarbSane's dire (and incorrect) opinion of LC eating based on the last of the triad. Cracking.So it is with Grey and Kipnis' paper on the irrelevance of fasting insulin to weight loss. It leads back to a rat paper (aren't you surprised!).
So ... "it leads back to a rat paper" because the authors cited a rat study (that they happened to be the researchers responsible for). How does this in any way mitigate the results of the HUMAN study to which I was referring? In any case, his readers had a bit of a field day at my expense spinning tales of conspiracy theories and whatnot. In the end, the only thing I got out of why Peter cited the whole rat thing was to show some sort of Axen-like bias on the parts of G&K who (paraphrasing) then "designed a study to get the desired result". This was first asserted by commenter Chris. Try as I may in the comments at Peter's, nobody seems to have any idea of how the study was designed to demonstrate that fasting insulin had NO bearing on weight loss in G&K's studies on human women, but it seems to be enough to some for these guys to merely state this in order for many to dismiss the study. *sigh*
Unless there was amputation/liposuction involved (there was not) or insulin levels were artificially manipulated (they were not), simply stating that G&K designed their study to garner a pre-determined desired result doesn't hold water. Put up or shut up on that point, to be blunt.
Eventually, Peter did address the actual G&K paper in humans. Fasting insulin and weight loss
I think that it might be a good idea to state here that I'm a calories-in calories-out sort of a person. Arguing about metabolic advantage is pointless. When a person loses weight they convert tissue to energy, amputations excepted. Where the calories go, whether it is BMR, thermogenesis, glycosuria, increased spontaneous movement, shivering etc, the calories always go somewhere. As far as I am aware no one is suggesting that calories evaporate. Certainly I'm not....Let's make this clear. Fasting insulin determines weight loss. The effect is primarily through reduced dietary caloric intake secondary to lipolysis-mediated access to adipose tissue calorie stores.
In between, he highlights the case of one subject who lost weight on maintenance level calories. Despite the fact that her fasting insulin jumped around, Peter's explanation was essentially that she ate less because with low fasting insulin she was less hungry. You can go see for yourself that I asked for clarification of this and received a rather nasty response. Somehow I'm the one incapable of reading and interpreting data for a study where fasting insulin levels and body weights were actually measured and reported. In his article, however, Peter cites another study where insulin levels were not reported, but "if we accept anything from GnK's work, I think we have to accept that under weight stability we can dial fasting insulin by adjusting carbohydrate intake." Huh? How scientific, to assume anything rather than looking at actual data.
So, here I will provide two more weight loss studies, among the hundreds I've read, and maybe thousands that have been conducted where fasting insulin levels HAVE been measured and reported.
First let's look at this study, I've blogged on previously and continues to provide evidence countering LC dogma. In a nutshell, this was NOT a weight loss study. " a weight-maintaining diet (15% protein, 35% fat, and 50% carbohydrate) for 2 wk, an isocaloric diet (30% protein, 20% fat, and 50% carbohydrate) for 2 wk, and an ad libitum diet (30% protein, 20% fat, and 50% carbohydrate) for 12 wk." Despite being given extra foods during the 12 week ad lib phase, the subjects reduced intake by ~440 cal/day on average and lost an average of 4.9 kg weight and 3.7 kg fat mass.
Did insulin levels, fasting or otherwise, have an impact here? Nope. Behold.
(square = maint. phase 1, dot = HP isocaloric, triangles = HP ad lib)
Not only did fasting insulin not differ, but overall insulin seems to differ very little here.
OK, but ... but ... but ... These diets were all 50% carbs ... whattabout low carb? Well, for this one we have a study that was cited by Westman et.al. discussing how low carb diets (really) work. Here, the obese men spontaneously cut around 1000 cal/day when carbs were severely restricted - and didn't replace carbs with increased fat or protein. The predictable result? They lost weight! Everyone please see King's avatar amongst my followers ;-)
(filled = before, open = after/LC)
Fasting insulin darned near identical.
So ... how many more studies should I post to support my contention that fasting insulin changes in an individual has absolutely squat to do with weight loss before someone challenges Peter on his unsubstantiated assertion?
I'm the one who can't read?