Insulin is a hormone produced by your pancreas. It plays an important part in controlling how you burn food for energy, store excess energy in your fat stores and break down your fat stores when you try to lose weight. Insulin is produced when you eat carbohydrate foods.
Some people make too much insulin, and this is called hyperinsulinemia or insulin imbalance. It can cause your blood sugar to go too low, making you feel tired and hungry for more food, even though you may just have eaten. Too much insulin also makes it easier for your body to store energy as fat, and harder for your body to break down your fat stores when you try to lose weight.
If you continually produce too much insulin, your cells can become insensitive to it. This is called insulin resistance. You produce more and more insulin but it has less and less effect. This causes sugar to build up in your blood and sometimes to spill over into your urine. Eventually, your pancreas can become worn out. At this point you are no longer able to produce enough insulin, and have become a type 2 diabetic. If you have insulin resistance, you may sometimes be referred to as -pre-diabetic for this reason.
It has been assumed for a long time that being overweight causes diabetes. It certainly makes your cells more likely to be insulin-resistant, and insulin resistance generally improves as excess weight is lost. However, many experts now see obesity as a symptom of diabetes, not the cause. They believe that the overweight is just the most obvious sign of what is going wrong in your body - it's your body's inability to cope with a diet full of insulin-triggering high carb foods that causes both the overweight and ultimately, the diabetes.
Experts believe that you can avoid type 2 diabetes, and often even reverse the disease once you have it, by avoiding the foods that stimulate the release of lots of insulin - that is, refined carbohydrate foods such as sugar, sweets and candy, cakes, cookies and pastries, white bread, pasta, white rice and potatoes.
Insulin resistance is one of the symptoms of a condition called metabolic syndrome or Syndrome X. It is also a symptom of PCOS (polycystic ovarian syndrome), which can cause excess body hair and weight gain especially around the waist and is also a leading cause of infertility. If you have one of these conditions, then losing weight is likely to be particularly difficult, especially if your diet is high in refined carbohydrates.
So the best diet for someone with insulin resistance or type 2 diabetes is a diet low in refined carbohydrate foods. This in effect means adopting a low GI (glycemic index), low GL (glycemic load) or low carb diet. However, many people have such a low tolerance for carbohydrate foods that they are unable to handle even the 'good' carbohydrates such as whole fruits and whole grains. If you are in this group, a low GI or low GL diet may not be effective in reducing your insulin levels and improving insulin sensitivity, and a low carb diet may be more suitable.
More about the connection between hormones like insulin and inability to lose weight can be found in the ebook "Why Can't I Lose Weight". If you want to know more about diets that help with insulin imbalance, insulin resistance and diabetes, the Easy Guide to Low Carb, Low GI & Low GL Diets explains what the differences are between these diets and how to do them. If you are looking for recipes which are good for insulin resistance and diabetes, the recipes in the "Low Carb / Low GI Cookbook" are particularly suitable.