Anytime insulin sensitivity is reduced it takes more insulin to get the job done (deposition of glycogen etc.) Prolonged low carbohydrate diets have been known to reduce insulin sensitivity thereby raising insulin levels with the re-introduction of carbohydrates. As to how much carbohydrate this takes in order to show its effects (elevated insulin) its been my experience as shown with blood test results that it doesn't take much and most definitely less than what glycogen stores in the muscles and/or liver are empty. Try this little experiment. Go on a very low carbohydrate diet for 1 week (<50 grams per day) and then get your hands on a glucometer and take fasting blood sugar results then take in a fair amount of carbs (100 grams or so) and chart the results every 30 minutes for 3 hours. What you'll probably find will closely resemble a hypoglycemic response curve which is indicative of high insulin levels.....this is despte the fact that obviously your muscle and liver glycogen levels would have been depleted beyond this 100 gram level. As to bodybuilders and cyclical ketogenic diets the re carb up does help to keep muscles full and help them lift heavy weights but the diet was originally created 20 some-odd years ago as a weight gain diet (The Ultimate Diet by i believe it was Zumpano). Insulin is a very anabolic hormone and by first depleting carbs and then re-carbing one is able to better reap the anabolic effects of insulin and thus induce an anabolic state which would results in greater muscle mass. _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp.