We all know that eating too much isn’t good for your health, but it’s also becoming increasingly evident that even eating a normal amount could be increasing your risk of developing various health problems and perhaps even shave years off your life. But this idea has largely been based on studies involving simpler organisms, although restricting calorie intake has recently been shown to reduce age-associated diseases and boost the lifespan of monkeys.

Now, scientists finally have some evidence that similar effects occur in humans, backing up what the same team observed in rodents. During a small trial, researchers discovered that following a diet designed to mimic the effects of fasting for just five days a month reduced risk factors for a range of health problems, including cardiovascular disease and cancer. Furthermore, all of these benefits came without any apparent major adverse effects.

At first glance, it seems an odd concept that slashing calorie intake should exert positive effects on health. But dietary restriction is known to induce changes in the cell and metabolism that affect things like inflammation and cellular damage caused by reactive, oxygen-containing molecules in the body, both of which are associated with a variety of diseases, such as cancer and dementia.

In support of this, intermittent fasting — an extreme form of dietary restriction — has been shown to help mice stave off cancer, heart disease and the progressive degeneration of brain cells. Furthermore, it has also been demonstrated to have some beneficial effects on humans, such as reducing blood pressure. But fasting is difficult for humans to follow, and can also be dangerous. So in order to examine its effects further, researchers from the University of Southern California instead came up with a diet that mimics fasting, eliciting the same effects on the body.

They first tested it out on mice in bimonthly cycles of just four days and starting during middle age, which was found to induce an impressive list of positive effects. It promoted the regeneration of multiple organs and systems, trimmed them of fat, reduced the incidence of cancer, rejuvenated the immune system and helped them outlive control animals by several months, which is lot for these short-lived animals.

Additionally, when they tried it out on old mice, it promoted the growth of brain cells in the region responsible for learning and memory, an effect complemented by an observed improvement in cognitive tests. And these effects weren’t simply due to an overall reduction in calories consumed since the control animals and the fasted animals were provided with the same total number of calories each month.

Taking this one step further, the researchers enrolled a small group of 19 human participants and trialed their diet on them. Daily Calorie intake was reduced to between 34 and 54% of the normal amount, or roughly 725 to 1090 Calories, which was followed for five consecutive days per month. After the fasting stint, they ate as they normally would.

As described in the journal Cell Metabolism, just three cycles of this diet tidied their waistlines, lowered blood glucose and reduced levels of molecules associated with diabetes, cardiovascular disease and cancer, compared to the control group.

These results are encouraging enough for the researchers to start thinking about seeking FDA approval for similar regimens, but they warn that people shouldn’t try fasting on their own as it isn’t suitable for everyone. Furthermore, if not carried out properly, it could be dangerous for health.