The health benefits of calorie restriction are well documented, but the reality of it for most people is more difficult. Fasting, even intermittent fasting, can be hard on the body – and not all researchers are convinced that its benefits outweigh its risks across the board. Now, a new study by a team at the University of Southern California finds that restricting calories for just five days out of the month can have profound effects on cancer risk, heart disease, inflammation, and maybe even brain disease. And the results seem promising not only in yeast and in rodents, but in humans as well. Of course, it still needs some more research before we all take it up, but the results are promising so far, and the FDA will evaluate its safety shortly.
The team first tried a fast mimicking diet (FMD) in middle-aged mice: Twice a month they were given a calorie-restricted diet for four days in a row. The rest of the month they ate as usual. By the end of the study, the mice who were on the regimen lived longer, had lower incidence of cancer, inflammatory diseases, and less bone loss; they were also better at learning and memory tasks than control mice (who ate the same amount of total calories but steadily, without the calorie-restricted times). The FMD group also had evidence of cell regeneration, including bone, liver, brain, and immune system cells.
In humans, the regimen was a little different: The 19 people, from 27 to 70 years old, ate their regular diets – whatever those might be – for 25 days of the month, and then ate a FMD for the last five days. For the humans, it consisted of 34-54% of the participants’ regular daily calories, broken down like this:
- On day 1, they ate just under 1100 calories, with 10% coming from protein, 56% coming from fat, and 34% coming from carbs.
- On days 2-5, they ate about 725 calories, with 9% coming from protein, 44% coming from fat, and 47% coming from carbs.
By the end of three months, the participants in the FMD group had reduced markers of aging, diabetes, inflammation, heart disease, and cancer. Importantly, the FMD was linked to lower levels of the hormone insulin-like growth factor 1 (IGF-I), which previous work has found is connected to cancer risk and aging. Protein consumption also appears to be connected to higher levels of the hormone, which is why the FMD used in this study had such low protein content.
The takeaway of the study, says researcher Valter Longo, is that the level of intensity of the “fasting” isn’t that great – and you may not even need to do it once a month. “You can obtain strong and long-lasting benefits against aging and diseases by undergoing a complex plant based diet we have formulated to obtain the anti-aging benefits of fasting without its detrimental effects. The FMD lasts only 5 days every month. We believe for most people this periodic intervention could still be very beneficial even if done every 3-6 months.”
Larger clinical trials are the next steps, and if they confirm the results seen here, then it’s possible that doctors and dietitians will prescribe the diet as a way to address various diseases, and as a tool for healthy aging in general.
“The diet will become available very soon for effects on biomarkers of aging," says Longo, "but it will have to wait for FDA approval to be prescribed to treat and prevent diseases. I will soon be presenting our data to the FDA in a seminar series organized in collaboration with the National Institute on Aging. Also, the company that makes the FMD (L-Nutra) will soon begin discussions with the FDA to pursue claims on the prevention and treatment of diabetes, cancer and cardiovascular diseases. We anticipate that the FDA will require rigorous protocols and trials but will be supportive.”
Longo adds that ultimately the diet is a way to help the body reboot itself every so often. “It’s about reprogramming the body so it enters a slower aging mode, but also rejuvenating it through stem cell-based regeneration and rejuvenation in multiple systems,” he says. “It’s not a typical diet because it isn’t something you need to stay on.” And that's very good news for most of us.
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