Saturday, March 19, 2011
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!). The rat model was developed to allow rats to gain weight under hypoinsulinaemic conditions. So GnK had a high carbohydrate diet and a low carbohydrate diet for their rats, both of which promoted weight gain, but the LC diet did it without raised insulin. Here are the diets:
But here's the funny part. They did a whole load of experiments (very interesting, seminal work on pancreatic glucokinase induction/suppression) which required equal calorie intake between a group on the high carbohydrate diet and another group on the zero carbohydrate diet. Let me quote:
"Since the low carbohydrate-high fat diet is less palatable to rats than the high carbohydrate diet, pair feeding was accomplished by determining the caloric intake of the low carbohydrate fed rats and then offering a comparable [ie less than they would have eaten] caloric amount of the high carbohydrate diet the following day to another group of animals."
You just have to admire the palate of those hypoinsulinaemic rats. Of course it's just possible they weren't ratty gourmands, it might actually be that they just weren't hungry because their fasting insulin was low and no one was ordering them to eat more than they felt like................
The giggles that come from following CarbSane's leads! Gotta get them from somewhere.
More on the cited Grey and Kipins 1971 paper when I've finished with the modern studies looking at the same question. There are some nice ones.