sâmbătă, 16 octombrie 2010

insulin

ultima parte dintr-o serie de articole interesante despre insulina aici

The bottom line is that insulin does not deserve the bad reputation that it has been given, and the “carbohydrates drive insulin which drives fat storage” mantra is wrong. To summarize:

Insulin suppresses appetite; it does not increase it
A high carbohydrate diet does not cause chronically high insulin levels
Protein is insulinemic, and in certain cases, can be just as insulinemic as carbohydrate
Contrary to popular belief, glucagon does not “cancel out” the suppression of lipolysis by insulin when protein is ingested
The insulinemic effects of protein are due to a direct stimulatory effect on the pancreas, and not because the protein is converted to glucose
The combination of protein and carbohydrate can produce greater insulin secretion than either one alone, yet high protein, moderate-to-high carbohydrate diets are very effective for weight loss
Very high carbohydrate diets have been demonstrated to produce weight loss when people are in an energy deficit
Dairy is extremely insulinemic, just as insulinemic as white bread, yet does not promote weight gain in the absence of an energy surplus. This is supported by a very large number of studies, including animal studies, observational studies, and randomized controlled trials.
Insulin is not required for fat storage
Insulin levels are not predictive of weight gain or weight loss in the majority of prospective studies
Exenatide restores rapid phase insulin release in diabetics, yet causes weight loss
The effects of insulin injection cannot be compared to normal physiological insulin release, since amylin is co-secreted with insulin from the pancreas
Insulin mainly functions as an inhibitory hormone rather than a storage hormone, acting as a brake on many important physiologic processes
A type I diabetic without insulin becomes hyperglycemic because of overproduction of glucose by the liver, not because insulin can’t get into cells
Insulin enhances the uptake of glucose into cells, but is not required for it
Insulin regulates blood sugar after a meal both by stopping the liver from producing glucose and enhancing glucose uptake into cells.
In a fasted state, insulin regulates blood sugar by controlling glucose production of the liver, not by affecting the uptake of glucose into cells
You cannot simply look at the temporary effects of insulin on lipolysis and glucose storage. You have to address what is happening over a 24-hour period; body fat will not increase if there is no overall energy surplus.

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