When Christopher Gardner, researcher of the famous A to Z diet study, went back through his data, he found those women who were most insulin resistant did better on a low carb diet, and those who were more insensitive did better on a low fat diet. http://www.nutritionaction.com/dail...-gain-and-loss/

If you want a good short explanation of IR, watch this 18 minute TedTalk. http://forum.lowcarber.org/showthread.php?t=467437

Most people can guess they are insulin resistant if they are overweight and have larger waist size.