A new mouse study finds potential risk of taking up the popular diet.

Though many people claim the keto diet to be a game changer or a lifesaver, a newly released study raises questions about its ability to cause type 2 diabetes.

The study, which was conducted on mice, evaluated the keto diet.

The keto diet is a low-carb, high-fat diet plan that causes the body to burn fat instead of carbohydrates — a process known as ketosis. This is said to help with weight loss.

The Journal of Physiology published the research, which said following the diet in its early phases could boost the risk for type 2 diabetes.

ETH Zurich along with the University Children’s Hospital Zurich conducted the study.

They fed mice ketogenic diets and high-fat diets and then tested their metabolisms and sugar responses.

They found that keto diets don’t allow the body to properly use insulin, so blood sugar isn’t properly controlled. That leads to insulin resistance, which can raise the risk for type 2 diabetes.

The researchers say they didn’t evaluate if the diet causes obesity after long-term use.

They called for additional research to better understand how keto diets affect the body. Researchers want to look at the mechanism behind the effects.

“Although ketogenic diets are known to be healthy, our findings indicate that there may be an increased risk of insulin resistance with this type of diet that may lead to type 2 diabetes,” said Christian Wolfrum, PhD, a professor at ETH Zurich and co-author of the research.

Gerald Grandl, PhD, co-author of the study and professor at the German Research Center for Environmental Health, said that insulin resistance and the keto diet have been studied before.

Studies on mice report different things, mostly improved or maintained insulin in muscle but impaired glucose tolerance systematically or in the liver alone.

A century ago, doctors had recognized that fasting or starvation for several days, or strict carbohydrate restriction (without starvation), can cause something called ‘starvation diabetes’ in rodents, dogs, and humans. Now Grandl thinks that’s similar to the findings in his paper.

“No one will get type 2 diabetes while on keto, simply because the carb intake is not high enough to develop any form of hyperglycemia,” he said.

What happens is the liver becomes insulin resistant, which he thinks is reversible when the person switches back to a high-carb, low-, or medium-fat diet. But adding carbs to a diet high in fats is definitely a bad idea, he said.

Dr. Stephen Phinney, co-founder and chief medical officer at Virta, a program that claims to reverse type 2 diabetes by drawing on ketosis, said there are no human studies that indicate a well-formulated keto diet causes type 2 diabetes.

“To the contrary, based upon many biomarkers that predict the incidence of type 2 diabetes, nutritional ketosis benefits all of them,” he told Healthline.

There’s a lot of research that’s suggested using carbohydrate restriction can help the disease, he added.

Phinney said that people struggle to follow a ketogenic diet if they have type 2 diabetes because they don’t find it sustainable.

Following a ketogenic nutrition plan can be difficult, which can be due to confusion around what constitutes a well-formulated ketogenic diet.

“There is simply no ‘one-size-fits-all’ solution, making individualization extremely important,” Phinney noted.

Phinney said research on mice is valuable, but not all conclusions in mice studies can be replicated in humans.

He also pointed out some limitations of the study, which include the diet only being used for three days. Additionally, the high-fat content of the diet was mostly from high amounts of vegetable shortening, which isn’t recommended for humans because it’s been shown to boost blood sugar and may harm the liver.

The study in mice is at odds with some previous research on the benefits of low-carb diets.

Previous short-term studies have shown that low-carb diets — including the keto diet — can improve glucose control in people with type 2 diabetes and lower the amount of medications they need, noted Dr. Reshmi Srinath, director of the weight and metabolism management program at the Icahn School of Medicine at Mount Sinai in New York.

There isn’t much data on long-term effects of low-carb eating.

“We also know that limiting carbohydrates to such a degree can be challenging for some patients and there can be a risk of hypoglycemia [low blood sugar] particularly in patients with type 2 diabetes,” Srinath said.

She said that short-term use of low-carb diets in people with diabetes has to be closely monitored by doctors.

She recommends carbohydrate moderation, and provides instruction on how people can count and manage carb intake along with the addition of physical activity.

Srinath said it’s too soon to establish a correlation between the keto diet causing type 2 diabetes. More research is needed.

Stephanie McKercher, a Colorado-based registered dietitian and recipe developer at Grateful Grazer, agreed. “It’s impossible to know whether the same results would occur in humans.”

“Overall, ketogenic research is still very limited, and we need more human studies to fully understand its effects.”

There are five basic recommendations for people who are overweight or obese, or experience adiposopathy, insulin resistance, prediabetes, and diabetes.

They focus on what to eat instead of what not to eat, according to Dr. J. Michael Gonzalez-Campoy, medical director and CEO of the Minnesota Center for Obesity, Metabolism, and Endocrinology, who worked on healthy eating guidelines with the American Association of Clinical Endocrinologists, the American College of Endocrinology, and The Obesity Society.

He said these recommendations include portion control, eating fresh foods, consuming plant-based meals, limiting animal products, and drinking water.

“The human body needs protein, carbohydrate, and fat. Digestion reduces these to circulating amino acids, glucose, and lipids, respectively,” he explained. “Depriving the body of any of the three macronutrients is not sustainable by most humans, and it forces the body to change its metabolic pathways to make up for the deficit.”

The observation that insulin resistance develops after fasting is not new, he added.

“The generation of ketones, free fatty acids, and an acid environment then contributes to a state of insulin resistance and also to impaired beta-cell function,” Gonzalez-Campoy said.

Gonzalez-Campoy doesn’t recommend going on any diet because that’s a short-term solution.

“It is best to teach patients the essence of healthy eating so they can sustain it over the course of their life,” he said.

Regardless of whether or not you want to try the keto diet, there are some people who shouldn’t for medical reasons.

Gonzalez-Campoy noted that people with chronic renal failure in stages 3, 4, or 5 should not follow the keto diet.

“The kidneys are essential to buffering the blood and the acidosis that develops from fasting may not be corrected. People with type 1 DM would be best off avoiding the keto diet — they are already at risk of ketoacidosis,” he explained.