We’ve long blamed carbs for making us fat. What if that’s wrong?
This latest salvo in the low-carb debate strikes me as ironic – a diet that actually works in search of a theory to explain why.
Read the full article at: www.vox.com
Burning More Fat
The original inspiration behind low-carb diets was simple: in the absence of carbohydrates, it was hypothesized, the body would turn to fat stores for energy. It turns out that this model is oversimplified so it was replaced by the “carb-insulin” model, which addresses the fat-storing effects of insulin.
Insulin not only helps your body absorb glucose for energy but it is also remarkably efficient at storing fat. People with metabolic syndrome and type 2 diabetes are insulin resistant, so they have high levels of circulating insulin, which explains why they store more fat.
The Carb-Insulin Model
Extrapolating on that concept, scientists developed the “carb-insulin” model to explain the fat loss seen with low-carb diets: eat fewer carbs – lower your insulin levels – store less fat. Simple, right?
The latest study published in the American Journal of Clinical Nutrition is a refutation of the carb-insulin model. In a highly-controlled environment (confinement to a hospital with every morsel of food accounted for), subjects’ drop in insulin levels correlated only weakly with increased energy burn and decreased fat storage.
NIH obesity researcher Kevin Hall, who led the study, concludes that the regulation of body fat storage has to do with more than just insulin levels and carbs consumed.
The End of Low-Carb?
This is hardly a death-knell for low-carb diets. Ok, so the carb-insulin model is flawed or incomplete. But the study only addresses the metabolic component of a change in macronutrient ratios – it fails to address what is arguably the more important effect: hunger control.
Hunger is the Key
The study was isocaloric and calorie-restricted – both diets had the exact same number of calories. This bears no resemblance whatsoever to real-world eating habits. Most Important, there is no way to know what effect the macronutrient ratio change had on subjects hunger and satiety. So what if they were allowed to snack, like everyone in the real world does? Would the low-carb subjects have eaten fewer junk-food calories between meals?
Even if the metabolic component makes a small contribution to fat loss, the appetite control that results from a macronutrient ratio change may make all the difference.