A shorter explanation from a gent with some nifty insights in the relationships between obesity, insulin, leptin and what causes what.
There's a key point here with relevance to the Taubes/Guyanet highlighted debate between the palatability theory of weight loss and the carb theory of weight loss. Guyanet and others in that camp point to the fact that insulin injected directly into the brain results in satiety, therefore, the carb theory, which hinges on the action of insulin in causing overeating and under activity, must be false.
Whenever I've read a report on that study - that insulin injected exogenously reduces hunger - I wonder why anyone would take that to mean anything significant. The idea that we can deduce the effect of insulting in the system, in the organism, from the effect of it being exogenously injected, is fraught with peril - as is any rational analysis of diet without massive long term well controlled intervention studies.
Lustig does a nice job of pointing out the difference between short term impacts of hormones, and the longer term impacts or chronic impacts.
It does make sense, of course, that if the body is secreting insulin to control a carb bolus, that it should also reduce hunger - at that moment. After all, there's a glucose crisis to deal with, which eating would exacerbate. Two hours later, when insulin is overdoing the job of saving the body from too much glucose, and blood sugar levels of dropping, it would also make sense that appetite would increase, which is what many people experience in their pattern of high carb eating. To say that the short term effect of exogenously injected insulin disproves the carb theory shows, to my mind, some defect of thinking - due to either a desire for the carb hypothesis to be wrong, or due to the tendency of many to mistake a measurable, discreet fact for the whole picture, which it is only a factor (and perhaps a minuscule one) in the whole picture. It appears that this kind of defective thinking often results from the specialist's confidence that they know more, perhaps their desperate need to believe that they know more, than those who don't share their credentials.
There's a key point here with relevance to the Taubes/Guyanet highlighted debate between the palatability theory of weight loss and the carb theory of weight loss. Guyanet and others in that camp point to the fact that insulin injected directly into the brain results in satiety, therefore, the carb theory, which hinges on the action of insulin in causing overeating and under activity, must be false.
Whenever I've read a report on that study - that insulin injected exogenously reduces hunger - I wonder why anyone would take that to mean anything significant. The idea that we can deduce the effect of insulting in the system, in the organism, from the effect of it being exogenously injected, is fraught with peril - as is any rational analysis of diet without massive long term well controlled intervention studies.
Lustig does a nice job of pointing out the difference between short term impacts of hormones, and the longer term impacts or chronic impacts.
It does make sense, of course, that if the body is secreting insulin to control a carb bolus, that it should also reduce hunger - at that moment. After all, there's a glucose crisis to deal with, which eating would exacerbate. Two hours later, when insulin is overdoing the job of saving the body from too much glucose, and blood sugar levels of dropping, it would also make sense that appetite would increase, which is what many people experience in their pattern of high carb eating. To say that the short term effect of exogenously injected insulin disproves the carb theory shows, to my mind, some defect of thinking - due to either a desire for the carb hypothesis to be wrong, or due to the tendency of many to mistake a measurable, discreet fact for the whole picture, which it is only a factor (and perhaps a minuscule one) in the whole picture. It appears that this kind of defective thinking often results from the specialist's confidence that they know more, perhaps their desperate need to believe that they know more, than those who don't share their credentials.
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