Ketogenic diet is a form of diet that consists of high fat and protein content and very low carbohydrate content. It has been known to promote weight loss and is considered to healthy. It has been adopted by many people globally.
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Now a new study on laboratory animals shows that ketogenic diet can raise the risk of getting type 2 diabetes. The study titled, “Short-term feeding of a ketogenic diet induces more severe hepatic insulin resistance than a obesogenic high-fat diet” appeared in the latest issue of the Journal of Physiology.
The researchers at the ETH Zurich compared the effects of western-style high-fat diet (HFD) and ketogenic diet (KD) on laboratory mice and found that the animals fed on KD were initially metabolically healthy but soon showed symptoms of reduced glucose tolerance. Impaired glucose tolerance is a key feature of type 2 diabetes. The impaired glucose tolerance among the KD group of mice was greater than those in the HFD group, the researchers noted.
Christian Wolfrum, Ph.D., co-corresponding author and associate professor of the Institute of Food Nutrition and Health at the ETH Zurich explained that diabetes is one of the largest public health issues at the present time. He said that although ketogenic diet is considered to be healthy, this study reveals that it may raise the risk of insulin resistance and type 2 diabetes.
The next step for the team is to find the underlying cause behind the diabetigenic effects of this type of diet. Dr. Wolfrum said that they are trying to discover if this glucose intolerance and insulin resistance that is seen due to ketogenic diet a form of physiological adaptation by the body.
He explained that in persons or animals on a ketogenic diet the body utilizes energy after breaking down fatty acids rather than carbohydrates. The break dwon products of the fatty acids could be signalling the brain in altered manner, he said and that could be the underlying reason for impaired glucose tolerance.
At present type 2 diabetes affects millions of people worldwide and till date the disease has been linked to unhealthy western style high fat and high carbohydrate diet along with a sedentary life with little or no exercise. There is a slow decline in insulin sensitivity in these patients. The blood glucose initially remains within control but the body requires more and more insulin to maintain the blood glucose. Eventually the insulin production from the beta cells of the pancreas fails to meet the demands of the body and glucose intolerance and type 2 diabetes develops.
The researchers write, “These early impairments of glucose homeostasis typically present as a failure of elevated glucose or insulin levels to suppress hepatic glucose output, leading to decreased glucose tolerance.” This is said of the animals fed on the high fat diet that also develop glucose intolerance and insulin resistance in the liver and brain after a few days. It may take longer for them to develop profound insulin resistance in the major organs.
There have been studies that show that starving oneself or eating a diet very low on carbohydrate such as in ketogenic diets can result in glucose intolerance and this is called starvation diabetes. However this is the first study that shows the long term effects on glucose tolerance and insulin sensitivity. It is well known that ketogenic diets help in weight loss but the effects on glucose tolerance and insulin sensitivity have been debated.
The team looked at the effects on glucose tolerance and insulin sensitivity on HFD and KD using metabolic tests and saw the effects on glucose production in the liver and glucose uptake in the muscle along with the sensititivity to insulin. They noted that mice fed on a HFD for three days showed a slightly impaired insulin signalling but no real glucose intolerance.
On the other hand mice fed on KD for three days had a little effect on insulin sensitivity. They were actually in a “healthy, glucose-tolerant state.” Now these KD and HFD fed animals were given a glucose challenge after three days. Both sets of animals showed impaired glucose clearance and insulin tolerance.
Results revealed that KD fed mice had developed hepatic insulin resistance. “The results of the present study demonstrate that, in the context of ad libitum feeding of both HFD or KD for a short period, the effect on systemic glucose tolerance is a result of the inability of insulin to suppress hepatic glucose output, whereas muscle and adipose tissue glucose uptake are completely unperturbed,” the authors wrote.
They explain that starvation diabetes and insulin resistance developing from short term KD diets may be occurring due to different mechanisms. More detailed studies are necessary to understand both, they explain.
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