Insulin, Weight & Fat Accumulation
Yes folks, if you go to any Biochemistry or Endocrinology text, you will find that insulin's action is to put fat into fat cells and suppress its release. Therefore insulin makes us fat. Lower insulin, lose weight. Raise insulin, get fat. Right?
I've recently posted on two rat studies (here and here) that demonstrate unequivocally that it is not so simple. I've also previously addressed the study that is the focus of this post in my Insulin Wars series with Todd Becker. But wanted to further highlight that study here in a separate post.
In this study, 7 young (13-30 yoa) obese women underwent various dietary interventions and basal insulin levels were measured.
The first leg involved diets intended to maintain weight. For 2 weeks they ate ad libitum usual diet to determine maintenance caloric levels, then they were given a low carb (25/53/22 C/F/P) isocaloric diet for 3 weeks followed by 3 weeks on an isocaloric high carb diet (62/18/20 ). The results are shown below.
The basal insulin had absolutely NO correlation to changes in weight. Five of the seven maintained their weights throughout the 8 weeks despite rather significant changes in their insulin levels. One subject seemed to lose a bit, but the weight loss in the LC phase continued through the HC phase despite skyrocketing insulin. One subject seemed to gain a bit on LC when insulin had been low, and maintained this but gained no more as insulin went up in the HC phase.
Next, they took 3 subjects and put them on 1500 cal/day hypocaloric diets. The protocol was as follows: 2 weeks ad libitum "maintenance", 4 weeks HC, 4 weeks LC, 4 weeks HC. The results are shown below:
Again, we see absolutely NO correlation between basal insulin levels and weight loss.
So ... Gary Taubes, as you continue to peddle your book and repeat how it is carbs and insulin that makes us fat, perhaps at some point you'll address evidence such as this that blows your hypothesis out of the water.
Four decades ago ...
Clearly, once obesity is established, insulin signaling goes out of whack and this study demonstrated that dietary carbohydrate does influence basal insulin levels. I've seen studies implicating impaired insulin clearance for this but can't put my finger on one just now.