Research Suggests Diet Plan May Reduce Biological Age by 11 Years

A University of Southern California (USC) study has suggested that a “fasting-mimicking” diet may reduce biological age by 11 years.

The study, which was led by the USC Leonard Davis School of Gerontology and peer-reviewed, was published on February 20 by Nature Communications, a scientific journal. It looked at two clinical trial populations, which each contained men and women between the ages of 18 and 70. A randomized set of patients adhered to the plant-based fasting-mimicking diet (FMD), while the control groups ate either a normal or Mediterranean-style diet.

The FMD patients underwent three to four monthly cycles in which they would adhere to the new diet for five days and then eat a normal diet for 25 days. The FMD consisted of vegetable-based soups, energy bars, energy drinks, chip snacks, and tea, as well as a supplement that provided “high levels of minerals, vitamins, and essential fatty acids,” according to the study.

The patients could choose when they would eat, but the amount that they could eat was limited. On day one of their five-day diet, they would consume 4,600 kJ or roughly 1,099 calories (11 percent protein, 46 percent fat, and 43 percent carbohydrate). On days two through five, they would consume 2000 kJ or roughly 717 calories (9 percent protein, 44 percent fat, and 47 percent carbohydrate).

The study used blood markers and other cellular and metabolic measurements to see how the FMD affected biological age.

“An analysis of blood samples from trial participants showed that patients in the FMD group had lower diabetes risk factors, including less insulin resistance and lower HbA1c results,” according to an article about the study written by Beth Newcomb and posted on the USC website.

“Magnetic resonance imaging also revealed a decrease in abdominal fat as well as fat within the liver, improvements associated with a reduced risk of metabolic syndrome. In addition, the FMD cycles appeared to increase the lymphoid to myeloid ratio – an indicator of a more youthful immune system.”

The study also showed that on average, FMD patients reduced their biological age by 2.5 years. It is important to note that in this context, biological age is measured by how well one’s cells and tissues are functioning.

However, the study suggested that if the diet was followed for a couple of decades, it could decrease one’s biological age by about 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 study said.

Limitations of the study

Dr. Dave Bridges, an associate professor of nutritional sciences at the University of Michigan’s School of Public Heath, explained the limitations of the study to Newsweek via telephone on Friday.

“I should say these were acknowledged by the authors as well. So, they’re using a proxy to measure age— a biomarker-based measure of age … none of those biomarkers are extraordinarily accurate or reproducible or generalizable,” he said.

“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 given to the 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 said. “So, for other people to be able to reproduce these effects, they would have to know exactly what the composition of the diet is.”

What does a dietitian say?

Dr. Lisa R. Young, a registered dietitian nutritionist and adjunct professor of nutrition at New York University, explained the benefits of a fasting-mimicking diet to Newsweek via email on Friday.

“A fasting-mimicking diet can offer various benefits, such as weight management, blood sugar control, inflammation reduction, and potential longevity advantages,” she said. “Calorie restriction, inherent to this diet, promotes longevity by lowering fasting insulin levels and reducing basal metabolic rate (BMR). Additionally, it may mitigate oxidative stress, thereby potentially reducing the risk of age-related ailments.”

But in the same breath, Young warned against the negative side effects of a low-calorie diet.

“I’m not quick to recommend [FMD] to clients I work with. Its restrictive nature may not suit everyone. Low-calorie intake can pose challenges for long-term adherence and may induce feelings of fatigue and deprivation.

“It is also not realistic or practical for the long term. Potential side effects like dizziness, fatigue, sugar cravings, and weakness should also be considered, as they may affect both physical and mental performance,” she said.

Bridges also warned that “if people on this diet are potentially less able to exercise,” because of fatigue, “that might counteract the pretty well-established benefits of exercise.” The professor said that exercise is “probably the lifestyle modification that people can do that is the most supported in terms of prolonged lifespan and healthspan.”