Insulin resistance (IR) is a pathological condition in which cells fail to respond normally to the hormone insulin.
To prevent hyperglycemia and noticeable organ damage over time, the body produces insulin when glucose starts to be released into the bloodstream, primarily from the digestion of carbohydrates in the diet. Under normal conditions of insulin reactivity, this insulin response triggers glucose being taken into body cells, to be used for energy, and inhibits the body from using fat for energy, thereby causing the concentration of glucose in the blood to decrease as a result, staying within the normal range even when a large amount of carbohydrates is consumed.
Carbohydrates comprise simple sugars, i.e. monosaccharides, such as glucose and fructose, disaccharides, such as cane sugar, and polysaccharides, e.g. starches. Fructose, which is metabolised into triglycerides in the liver, stimulates insulin production through another mechanism, and can have a more potent effect than other carbohydrates. A habitually high intake of carbohydrates, and particularly fructose, e.g. with sweetened beverages, contributes to insulin resistance and has been linked to weight gain and obesity. If excess blood sugar is not sufficiently absorbed by cells even in the presence of insulin, the increase in the level of blood sugar can result in the classic hyperglycemic triad of polyphagia (increased appetite), polydipsia (increased thirst) and polyuria (increased urination).
Avoiding carbohydrates and sugars, a no-carbohydrate diet or fasting can reverse insulin resistance.