A USC study suggests that a “fasting-mimicking” diet can lower biological age by 11 years.
The study, coordinated by the USC Leonard Davis School of Gerontology and peer-reviewed, was published on February 20 in Nature Communications, a scientific journal. It examined two clinical trial populations, each containing men and women aged 18 to 70. A randomized group of patients followed a plant-based fasting-mimicking diet (FMD), whereas the control groups ate a normal or Mediterranean-style diet.
The FMD patients went through three to four monthly cycles in which they followed the new diet for five days before returning to their regular diet for 25 days. The FMD included vegetable-based soups, energy bars, energy drinks, chip snacks, and tea, as well as a supplement with “high levels of minerals, vitamins, and essential fatty acids,” according to the study.
Patients may pick when they ate, but the amount they could eat was regulated. On day one of their five-day diet, they would ingest 4,600 kJ, or approximately 1,099 calories (11 percent protein, 46 percent fat, and 43 percent carbohydrates). From days two to five, they would ingest 2000 kJ, or approximately 717 calories (9 percent protein, 44 percent fat, and 47 percent carbohydrate).
To determine how FMD changed biological age, the researchers examined blood indicators as well as other cellular and metabolic studies.
According to Beth Newcomb’s article on the USC website, the FMD group had lower diabetes risk markers, such as insulin resistance and HbA1c levels, based on blood sample analysis from trial participants.
“Magnetic resonance imaging also demonstrated a reduction in stomach and liver fat, which is related with a lower risk of metabolic syndrome. In addition, the FMD cycles appeared to enhance the lymphoid to myeloid ratio, indicating a more young immune system.”
According to the study, FMD patients reduced their biological age by an average of 2.5 years. It is vital to highlight that biological age is determined by the efficiency with which one’s cells and tissues work.
However, the study found that if the diet was maintained for a few decades, one’s biological age might be reduced by approximately 11 years.
“A simulation of the effect of 3 FMD cycles for twenty years assuming continued efficacy of this dietary intervention suggests a potential decrease in biological age of about 11 years,” the authors of the study stated.
Dr. Dave Bridges, an associate professor of nutritional sciences at the University of Michigan School of Public Health, discussed the study’s shortcomings.
“I should mention that the authors acknowledged these as well. “They’re using a proxy to measure age—a biomarker-based measure of age… none of those biomarkers are extraordinarily accurate, reproducible, or generalizable,” he explained.
“The best possible design would be to follow people for long enough to see if they get age-related diseases, which isn’t feasible enough in a three-month study.”
Bridges also questioned what was in the soups and snacks provided to FMD patients.
“I would say the other big limitation is there’s some lack of transparency about exactly what the diet was because it’s these proprietary blends of soups and energy bars and things like that,” he went on to remark. “So, for other people to be able to reproduce these effects, they would have to know exactly what the composition of the diet is.”
Dr. Lisa R. Young, a registered dietitian nutritionist and associate professor of nutrition at New York University, discussed the benefits of a fasting-like diet.
“A fasting-mimicking diet can offer various benefits, such as weight management, blood sugar control, inflammation reduction, and potential longevity advantages,” she went on to say. “The caloric restriction inherent in this diet enhances longevity by lowering fasting insulin levels and basal metabolic rate (BMR). Additionally, it may reduce oxidative stress, potentially lowering the incidence of age-related illnesses.”
In the same breath, Young warned of the harmful consequences of a low-calorie diet.
“I am not quick to recommend [FMD] to the clients I work with. Its limited nature may not be suitable for everyone. Low-calorie diets can be difficult to maintain over time and may cause feelings of weariness and deprivation.
“It is also not realistic or practicable in the long run. Potential adverse effects such as dizziness, weariness, sugar cravings, and weakness should be evaluated because they can impair both physical and mental function,” she stated.
Bridges also cautioned that “if people on this diet are potentially less able to exercise,” due to weariness, “that might counteract the pretty well-established benefits of exercise.” The professor stated that exercise is “probably the lifestyle modification that people can do that is most supported in terms of prolonged lifespan and healthspan.”