With commentary by lead study author Valter Longo, PhD, director of the Longevity Institute at the University of Southern California, Los Angeles
New research has found that following a diet that mimics fasting, but is less difficult, may slow aging and reduce the incidence of chronic diseases including diabetes.
The study builds on an existing body of research that shows that fasting can prolong life in animals, and reduce the incidence of chronic diseases like diabetes, heart disease cancer and dementia. Fasting “kills damaged cells, switches healthy cells into a protected mode, and generates new young cells,” says Valter Longo, PhD, director of the Longevity Institute at the University of Southern California, Los Angeles.
But fasting is very hard for people to do and in some cases risky. “We were searching for strategies that delay aging, rejuvenate and reduce disease incidence, but that would be feasible for most people. I think we found it,” says Longo, the lead author of the new study.
Longo’s group set out to find a way to mimic the effects of fasting with a low calorie diet. The study, published in Cell Metabolism, showed some of the same health benefits in people who followed the fasting mimicking diet (FMD) for five days.
The study had three parts, beginning at the cell level in the laboratory, moving to mice and then to a small group of people.
In the animal study, mice were fed the restricted diet for four days twice a month and could eat as much as they wanted in between those cycles. After each FMD cycle, the mice had lower blood glucose, insulin and had reductions in certain inflammation factors like insulin-like growth factor 1 (IGF-1), which is associated with aging and cancer.
At 28 months, the mice on the FMD also had lost weight and had less abdominal fat, the belly fat associated with diabetes, compared to control mice. And the fasting mice had increased life spans.
In the human trial, subjects followed a very controlled diet specifically designed to reduce risks of fasting but provide essential nutrients and minimize the psychological difficulty of fasting. They were given specifically formulated vegetable-based soups, energy bars, energy drinks, chips, chamomile tea and a supplement, all created by L-Nutra (Longo is a major shareholder in L-Nutra, but has committed 100 percent of his shares to charity).
On the first day of the five-day diet, they could eat 1,090 calories, and on the remaining days, they ate only 725 calories. The diet was 9 percent protein, 44 percent fat and 47 percent carbohydrates. A total of 19 subjects stayed on the diet for five days once a month for three months and were compared to 19 participants who ate their regular diet.
Those on the FMD diet lowered their fasting blood glucose by 11.3 percent. “This is one of the best treatments for diabetes,” says Longo. But he warned that it is unsafe for those taking insulin or any medication for diabetes because the diet could cause glucose to drop to unsafe levels.
The study also found that IGF-1 was reduced by 24 percent and CRP levels, a marker for inflammation, was also lower. Subjects lost 3 percent of their weight and had lower belly fat than controls, and saw a host of other benefits to their health.
Longo says he’d recommend a fasting-mimicking diet to anyone who wasn’t on medications, but if you have an illness, you should follow it under the care of a physician.
For those primarily concerned with improving glucose control, there are a number of structured very low calorie diets, like Jenny Craig, that can achieve this. “I often find that the patient who wants to achieve weight reduction, has type 2 diabetes or prediabetes and especially those who are overweight would benefit from a structured jump start approach,” says Laurie Block RDN, CDE, a diabetes educator at the pediatric obesity program at NewYork-Presbyterian/Weill Cornell Medical Center.
“This structure can help temporarily ease the preplanning involved in preparing healthy meals, prevent overeating, and provide an awareness of portion control,” she says. But these types of programs are not that easy for people to follow over the long term, she adds.