Not eating over 500 calories a day! Yow!
Your body probably thinks it's starving so it is storing fat instead of burning it off. I would suggest that you take up your calorie intake. Your body needs food in order to have the energy to burn off the fat!
The difference between impact carbs vs. total carbs is as follows:
"Effective Carbs & Non-impact Carbs. The FDA previously preferred a disclaimer on all wrappers, which was an asterisk noted on the bar stating that, "not all the carbs were counted in the total carb count as they have a neglible impact on your blood sugar." This was the standard until recently, when the FDA contacted manufacturers regarding a change in guidelines. They now require full disclusure of total carbohydrates, but because they recognize that not all carbohydrates effect the body, the non-effective carbs (Maltitol, Glycerin & Fiber) are subtracted from the total to give the consumer the number or carbs that will effect their body and blood sugar.
All carbohydrates cause a spike in blood sugar. Simple carbs cause it quickly and complex carbs more slowly. (Simple carbs consist of all sugar, white flour, white flour pasta's, all rice and potatoes, to name a few. Complex carbs are veggies and salad greens, just to name a few) To complicate matters, carbohydrates are comprised of several sub-groups, which include dietary fiber, sugar, sugar alcohol, and "other" carbohydrates-kitchen sink grouping of gums, lignans, organic acids and flavenoids. (These individual items can be assayed.) The FDA requires that a nutrition label include the total carbohydrates.
Not all types of carbohydrates behave the same way in your body. For example, when your body digests table sugar, it turns immediately into blood sugar. So sugar and most other carbohydrates are what we call "digestible carbohydrates." Other carbs, such as sugar alcohol or glycerin, can be digested but do not turn to blood sugar. Still others, such as dietary fiber, are indigestible and pass through your body without impacting your blodd sugar level at all." from
www.thinkproducts.com/effective.html
So when you see impact carbs those are the bad boys that can effect your blood sugar levels much quicker than the "good" carbs.
Hope this helps!
Kiks