Keto Diet Only Beneficial for 1 Week Mice Study Suggests Everyday Health MenuNewslettersSearch Ketogenic Diet News Keto Diet Only Beneficial for 1 Week Mice Study SuggestsAfter one week on the ketogenic diet, mice began to accumulate fat, and develop obesity and type 2 diabetes. But more research in humans is needed. By Becky UphamJanuary 30, 2020Everyday Health ArchiveFact-CheckedFollowing the keto diet for more than seven days harmed mice's metabolic health, the early study found.Utamaru Kido/Getty Images; Everyday HealthYou probably know someone who has lost weight on the ketogenic diet. But critics argue that the high-fat, low-carb eating approach is difficult to sustain, and research on keto is limited. A mice study published in January 2020 in Nature Metabolism may help scientists understand the effects of the diet in humans — as well as its limitations. In their preliminary study, authors found that the benefits of keto ceased after only one week. After that, the rodents began to store fat and regain lost weight. The authors write that these findings suggest that the keto diet may provide benefits, such as a lower risk for type 2 diabetes and reduced inflammation, if followed short term, though more studies are needed. “Obesity and type 2 diabetes are lifestyle diseases,” says lead author Vishwa Deep Dixit, PhD, a professor of comparative medicine and immunobiology at Yale School of Medicine in New Haven, Connecticut. “Diet allows a way for people to be in control,” he says. Indeed, while genetics play a role in the development of obesity and type 2 diabetes, lifestyle choices also matter, according to a separate article published in June 2018 in Circulation: Genomic and Precision Medicine. RELATED: Does the Ketogenic Diet Work for Type 2 Diabetes? Keto Leads to Short-Term Metabolic Benefits in Mice For the current study, authors defined a ketogenic diet as one that provides 99 percent of calories from fat and protein and less than 1 percent from carbohydrates. (There are various versions of keto.) The mice in the standard diet group ate chow composed of 58 percent carbohydrates, 24 percent protein, and 18 percent fat. The ketogenic diet group ate chow with a calorie content breakdown of 87.5 calories from fat, 10.4 percent of calories from protein, and 0.1 percent calories from carbohydrate. When faced with a dramatic reduction in carbs, the body is deprived of the normal source of energy — the sugars from carbs — it starts breaking down stored fat into molecules called ketone bodies to use as a source of energy. That shift, called ketosis, usually takes about two to four days, according to Harvard Health. What Is the Keto Diet Researchers studied the mice for a few months. Once they began burning ketone bodies (a sign of ketosis), investigators observed an expansion in gamma-delta T-cells throughout the body. “Ketone bodies are a potent activator of gamma-delta T cells, which are key tissue protective immune cells,” says Dr. Dixit, noting that this was a key finding of the study. Though few in number, these cells are part of the initiation and spread of immune responses, according to Nature.com. The expansion of the gamma-delta T cells due to the keto diet are an important mechanism that improves metabolic health in mice, reducing inflammation and diabetes risk, he adds. RELATED: 10 Steps Beginners Should Take Before Trying the Keto Diet After 1 Week on Keto Fat Storage Obesity and Type 2 Diabetes Happened This situation was only temporary, though. When the body is in “starving-not-starving” mode brought on ketosis, the mice began to store fat simultaneously with fat breakdown. After about a week, the mice weren’t able to burn all the fat they consumed, and they developed diabetes and obesity. This is likely because the mice lost the protective gamma-delta T-cells in the fat, the researchers wrote. Researchers continued to follow the mice to see how the keto diet would affect their metabolic health. After two to three months, the keto mice gained significantly more weight compared with standard chow control group, and they also had elevated fasting blood glucose. The authors concluded, “All together these data indicate that long-term ad libitum keto diet feeding (eating as much or as little as one wants) in mice promotes obesity-related inflammation and loss of glycemic control.” RELATED: A Detailed Guide to the Potential Health Benefits and Risks of the Keto Diet Mice Research Doesn t Always Translate to Humans The fact that the ketogenic diet had a long-term negative impact on the health of the mice is not surprising, says Fatima Cody Stanford, MD, MPH, an obesity medicine expert at Massachusetts General Hospital in Boston. “The existing research on [the] ketogenic diet has mostly been in persons who have seizure disorders, particularly children who have refractory seizure disorders,” or epilepsy, says Dr. Stanford. “For us to presume that the ketogenic diet has long-term health benefits that are associated with weight loss is really a bit premature. We don’t have the data to back that up in a human population,” she says. It’s important to note that there are several steps up from mice to humans, though, says Stanford. “We need to take that into consideration when considering the findings of short-term benefits and long-term negative effects found in this study,” she says. “What we do know is that acutely we do see people lose weight on the keto diet; this mimics what we’ve seen with Atkins-type diets that are higher in fat with lower carbs, although keto is a little more extreme,” says Stanford. “But we find that this kind of diet is not sustainable over the long-term for most people,” she says. RELATED: What’s the Difference Between Keto and Atkins? Following the Keto Diet May Pose Health Risks to Humans “We also have to think about the health implications associated with this. According to this study, at least on mice, we saw fat being retained in areas that people may not have anticipated,” says Stanford. Stanford has seen negative effects in her patients who have put themselves on a ketogenic diet. “Not at my suggestion, because I never recommend this type of diet to my patients,” she adds. Stanford cites a case report that she published with a junior faculty member in January 2020 in the journal Cureus, which featured a participant who self-initiated a ketogenic diet that contained mostly eggs, cheese, butter, oil, nuts, leafy green vegetables, and almond and coconut milk. Over two months, the woman lost about 6 pounds (lbs) from her starting weight of 170.5 lbs, but she also had a marked increase in liver enzymes and her total LDL or “bad” cholesterol levels had climbed from 156 to 216 milligrams per deciliter (mg/dL). Lab testing and an ultrasound suggested hepatic steatosis, or fatty liver disease. After the participant stopped the keto diet and began eating a more balanced diet rich in fruits and vegetables, her liver enzymes resolved completely within eight months, and her LDL returned to its previous pre-keto diet level after one year. “This is just one example, but I think it highlights that people should be very cautious before jumping on the next diet fad,” says Stanford. “These kinds of diets are not without their potential side effects. Just because people look good on Instagram, they might think that means everything is good internally, and we’re often finding that that is not the case.” RELATED: The 11 Biggest Keto Diet Dangers You Need to Know About NEWSLETTERS Sign up for our Diet and Nutrition Newsletter SubscribeBy subscribing you agree to the Terms of Use and Privacy Policy. 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