Adverse effects of the diet include impaired growth, which can be caused by a nutrient deficiency, as well as an increased risk of getting kidney stones.
Research has shown that low-carb meals produce a chemical called beta-hydroxybutyrate (BHB)
BHB is a ketone, which is a chemical compound that is a byproduct of the process of fat breaking down in the liver. Ketones serve as alternative metabolic fuels for the brain and heart.
BHB is produced when someone adheres to a low-carb, high-fat diet. This happens because when they turn off access to gluclose - a primary fuel derived from eating carbohydrates - the body taps into its own fat stores for energy. This process is called ketosis.
For one of the two new studies, researchers from the University of California Davis fed mice a ketogenic diet, which was 90 percent fat. They started the mice on the diet when they had turned one, which is middle age for them.
Study researcher Jon Ramsey said: "We designed the diet not to focus on weight loss but to look at metabolism. What does that do to aging?"
The mice were tested at various ages in tasks such as mazes, balance beams and running wheels.
The study concluded that a ketogenic diet provided the mice that followed it with a host of health benefits.
The diet increased their memory, coordination and strength during old age. It also reduced inflammation and the incidence of tumors.
The ketogenic diet-fed mice had a lower risk of dying as they aged from one to two years old but their maximum lifespan did not change.
They performed at least as well on memory tests during their old age - two years old - as they had during middle age. This was compared to mice who were fed a normal diet and showed an expected age-associated decline.
Additionally, the mice on the ketogenic diet explored more.
Professor Ramsey said: "The results surprised me a little. We expected some differences but I was impressed by the magnitude we observed: a 13 percent increase in median life span for the mice on a high-fat vs high-carb diet."
"In humans, that would be seven to 10 years. But, equally important, those mice retained quality of health in later life," he added.
Professor Ramsey also said that the results were applicable to humans.
"At a fundamental level, humans follow similar changes and experience a decrease in overall function of organs during aging," he said, adding that the study "opens a new avenue for possible dietary interventions that have an impact on aging".
The second study, from the Buck Institute for Research on Aging, confirmed that the keto diet improved lifespan and memory in aging mice.
Tests on the mice checked for heart function and gene regulation changes through DNA analysis.
Researcher Dr Eric Verdin, who worked on the second study, said: "The fact we had such an effect on memory and preservation of brain function is really exciting."
"The older mice on the ketogenic diet had a better memory than the younger mice. That's really remarkable," he added.
Dr Verdin said that the two new studies reinforce each other and "show the same global effect on healthspan".
Researchers are exploring a molecule that mimics BHB to see if simply taking it as a supplement can induce the same benefits of a ketogenic diet.
However, Dr Verdin expressed skepticism about its effectiveness, saying: "The ketogenic diet is a complicated, drastic diet to follow. Can we reduce all of this beneficial effect to one molecule?"
