Insulin resistance is thought to be an important contributing factor to the modern diseases of civilization such as metabolic syndrome, blood lipid disorders, hypertension, obesity and type II diabetes.1 Although genetics play a role in insulin resistance, the observation that obesity and diabetes are increasing at alarming rates worldwide suggests that there are vital environmental factors that also need to be considered.2 


Although carbohydrates play an integral role in insulin resistance by elevating glucose levels, there is also strong evidence that the amount and quality of free fatty acids consumed contributes to insulin sensitivity.3 It has been shown in rats that under certain circumstances, free fatty acids are required for glucose-stimulated insulin resistance. Essentially, when rats are infused with a high level of glucose, in the absence of fatty acids, the insulin response is non-existent.4 In contrast, when this occurs in the presence of high levels of free fatty acids, glucose-stimulated insulin resistance is extremely elevated. It was shown in these studies on rats that the amount of saturation of the fatty acid was also correlated with insulin secretion.5 The more saturated the fat, the higher the insulin burst. Thus, in rats, it seems that free fatty acids are vit al to produce glucose-stimulated insulin resistance, and, of these, saturated fats have the
 most detrimental effects.


Whether this occurs in humans was investigated by Vessby et al. (2001), who established that the amount and quality of fat in the diet could also be important for the development of insulin resistance in our species. A group of 162 healthy subjects were given an isocaloric diet high in either saturated or monounsaturated fat for three months. As in rats, insulin resistance depended on the amount of fatty acids consumed and the saturation of those fatty acids. When the amount of energy gained from fat was greater than 37%, it was found that insulin sensitivity was impaired in both the saturated fat group (-7.8%) and the monounsaturated fat group (-3.3%). However, when the amount of energy coming from fat was less than 37%, a significant difference was found with saturated fat still decreasing insulin sensitivity (-12.5%) and monounsaturated fat increasing it (+8.8%). Within the context of this study, it would seem that insulin resistance can be improved
 on a diet c onsisting of less than 37% of energy from fat, with this fat coming predominantly from monounsaturated fatty acids.




'Government is like a baby: An alimentary canal with a big appetite at one end and no sense of responsibility at the other.' 
- Ronald Reagan