The role of insulin resistance in the development of muscle wasting during cancer cachexia.

BACKGROUND: Cancer cachexia is a complex syndrome associated with multiple metabolic abnormalities. Insulin resistance is present in many cancer patients and may be one mechanism through which muscle wasting occurs. METHODS AND RESULTS: The present review examines evidence in support of a role for insulin resistance in the development of muscle wasting during cancer cachexia and identifies areas for future research. Patients suffering from cancer cachexia tend to exhibit insulin resistance and improvements in insulin resistance have the potential to improve cachexia symptoms. In addition, evidence suggests that insulin resistance may occur prior to the onset of cachexia symptoms. CONCLUSIONS: Further investigation of the role of insulin resistance in cancer cachexia is needed. The use of translational research in this area is strongly encouraged, and has important implications for clinical research and the treatment and prevention of cancer cachexia.

Glucose tolerance in response to a high-fat diet is improved by a high-protein diet.

Consumption of a high-fat (HF) diet results in insulin resistance and glucose intolerance. Weight loss is often recommended to reverse these metabolic alterations and the use of a high-protein (HP), low-carbohydrate diet is encouraged. In lean rats, consumption of a HP diet improves glycemic control. However, it is unknown whether this diet has a similar effectiveness in rodents with impaired glucose tolerance. Rats were fed a HF or a chow (CH) diet for 6 weeks and then switched to a HP diet or a CH or pair-fed (PF) to the amount of kcals consumed per day by the HP group. Following the diet switch, body weight gain was attenuated as compared to HF rats, and similar between HP, CH, and PF rats. Despite similar weight progression, HP and PF rats had a significant decrease in body fat after 2 weeks, as compared to HF rats. In contrast, CH rats did not show this effect. Glucose tolerance was attenuated more quickly in HP rats than in CH or PF rats. These results indicate that a HP diet may be more effective than a balanced diet for improving glycemic control in overweight individuals.