How does keto, Mediterranean diet, or intermittent fasting lead to healthy aging?
A new scientific review published in Nutrients examines how diet influences aging, highlighting its crucial role in contributing to both longevity and healthspan.
The review examined four specific dietary patterns, including caloric restriction, intermittent fasting, the Mediterranean diet, and the ketogenic (keto) diet, for their potential aging benefits.
The findings suggest that these dietary patterns may support healthy aging by influencing critical pathways in the body, including those related to cellular repair, inflammation, and metabolic regulation.
Understanding how diet directly impacts aging is crucial for improving or maintaining quality of life as we age and preventing age-related chronic diseases.
What dietary patterns lead to healthy aging?
As birth rates decrease and people live longer, the global population is aging significantly. However, living longer does not necessarily mean enjoying more years in good health.
So, there is a pressing need to enhance healthspan — the period of life spent in a healthy state, free from chronic diseases and age-related disabilities.
To address this issue, researchers in Romania reviewed various studies to determine how four particular diets might influence healthy aging, analyzing their impact on molecular pathways in the body.
These diets included:
intermittent fasting
the Mediterranean diet
the ketogenic diet.
The researchers chose these diets for their significant presence in current research and their diverse methods of supporting health and longevity.
As a scoping review, the team broadly searched for studies that evaluated the effect of these diets on longevity and healthspan in microorganisms, animal models, or humans.
Their research involved examining databases like PubMed, Scopus, and Web of Science. They excluded studies not in English or published before 2000 unless they were considered “foundational.”
While further studies are needed, the findings from the reviewed studies highlight the distinct impacts that each dietary pattern might have on promoting healthspan.
Caloric restriction
Restricting calories appears to mainly promote healthy aging by contributing to weight loss and obesity prevention, reduced inflammation, improved cardiometabolic health, and slowed biological (cellular) aging.
This potentially delays the onset of age-related diseases.
Calorie restriction has also been linked to longevity across various species.
Intermittent fasting
Intermittent fasting involves alternating between periods of fasting and normal eating.
This dietary pattern may offer short-term benefits in body composition and cardiovascular health. It may also provide long-term advantages, such as better cholesterol, thyroid modulation, and decreased pro-aging amino acid methionine.
Compared to continuous calorie restriction, intermittent fasting cycles may lead to superior improvements in insulin sensitivity and cellular stress responses, potentially offering greater benefits in cellular stress resilience and longevity.
Mediterranean diet
The Mediterranean diet is abundant in plant-based foods like fruits, vegetables, nuts, legumes, whole grains, and olive oil. It also generally includes moderate amounts of dairy and omega-3-rich fish while limiting meat and ultra-processed foods.
Following a Mediterranean-style diet may lower body mass index (BMI), support cognitive function and memory, slow biological aging, and reduce frailty in older adults.
This dietary pattern focuses on nutrient-dense, high-quality foods. It appears to enhance gut health and reduce inflammation by encouraging healthy gut bacteria and the production of short-chain fatty acids.
It is generally high in nutrients like unsaturated fats, fiber, and antioxidants that promote insulin sensitivity, cardiovascular health, and healthy aging.
The review authors suggest a Mediterranean-like diet may offer metabolic benefits similar to calorie restriction or intermittent fasting without cutting calories.
Ketogenic diet
The ketogenic diet is a high-fat, moderate-protein, very low-carbohydrate diet that causes the body to burn fat rather than carbohydrates for fuel.
The present review suggests this dietary pattern may improve triglyceride levels, increase good cholesterol (HDL), and help with short-term weight loss. However, it may also raise bad cholesterol (LDL) levels, at least temporarily, which could be a heart health risk for some.
By substantially reducing carbohydrate intake, the ketogenic diet decreases insulin-related activity and encourages autophagy, potentially aiding cellular detoxification and promoting longevity. According to the review authors, these effects are similar to those triggered by calorie restriction and intermittent fasting.
However, the ketogenic diet might also reduce appetite and promote gastrointestinal issues. This suggests further research is needed to assess its safety as a long-term dietary strategy for healthy aging, especially for older adults.
Understanding the main metabolic pathways
Medical News Today spoke with Thomas M. Holland, MD, MS, a physician-scientist and assistant professor at the RUSH Institute for Healthy Aging, RUSH University, College of Health Sciences, who was not involved in the study.
He described the main metabolic pathways involved in the health benefits of the four studied diets, including, most prominently:
These key pathways are involved in insulin signaling and may directly enhance longevity and prevent age-related diseases.
Holland said that “the mTORC1 and AMPK pathways are critical in regulating cell growth, energy balance, and metabolism, which are all essential for healthy aging.“
He noted that “mTORC1 is like a growth switch in cells that responds to nutrient levels.” This pathway becomes overly active when we are consistently in an overfed state with an abundance of nutrients available, “which can speed up aging by focusing on growth rather than maintenance.”
“By reducing mTORC1 activity—through dietary interventions like caloric restriction or intermittent fasting—cells shift towards repair and maintenance processes, such as autophagy, rather than growth, which can help slow aging,” he explained.
On the other hand, “AMPK is the body’s energy sensor. It gets activated when energy is low, like during fasting, and it works to conserve energy and protect cells from stress. AMPK also helps keep mTORC1 in check,” Holland stated.
Calorie restriction, intermittent fasting, and ketogenic diets may similarly impact these pathways by lowering calorie or carbohydrate intake. However, the Mediterranean diet might influence these pathways indirectly through its rich unsaturated fats and antioxidants, which can enhance insulin sensitivity and blood vessel function.
Holland summarized that “together when mTORC1 activity is reduced and AMPK is activated, cells manage energy more wisely and reduce damage, which can help extend both lifespan and the time we spend in good health.“
How to combine dietary strategies for healthy aging
Alyssa Simpson, RDN, CGN, CLT, a registered dietitian, certified gastrointestinal nutritionist, and owner of Nutrition Resolution in Phoenix, AZ, who was not involved in the study, told MNT that “the evidence on dietary interventions is valuable for impacting healthspan and quality of life, but varying study quality and methodological limitations [in the present review] require cautious interpretation.”
Still, among the studied diets, Simpson recommends the Mediterranean diet “due to its wide-ranging benefits and overall support for health.”
For individuals with weight management goals, she suggests including moderate calorie restriction to promote healthy aging, provided that nutritional needs are met.
Kiran Campbell, RDN, a registered dietitian specializing in heart health at Kiran Campbell Nutrition, who was not involved in the study, advised the same pairing of dietary patterns.
“Because of the increasing incidence of obesity and obesity-related disorders, a Mediterranean diet with caloric restriction may be a feasible approach to disease prevention,” she noted.
Both dietitians cautioned against intermittent fasting or ketogenic diets for healthy aging or disease prevention, citing concerns over long-term sustainability, potential nutrient deficiencies, and questionable effects on heart health.
On the other hand, Holland argued that combining the Mediterranean diet with calorie restriction or intermittent fasting strategies might amplify their benefits. “For example,” he said, “pairing intermittent fasting with the Mediterranean diet can provide both metabolic flexibility and a steady supply of nutrients that promote healthy aging.”
However, he emphasized that:
“A one-size-fits-all approach may not work; individual preferences, metabolic health, and specific health goals should guide the choice of dietary interventions. Additionally, ensuring actual implementation and maintenance of these dietary strategies is an important facet that requires knowledge dissemination and motivation.”
Ultimately, the experts agree that promoting healthy aging requires a comprehensive approach. This includes dietary changes, regular exercise, stress management, and fostering social connections.
Consult your doctor or registered dietitian to develop a personalized plan to enhance your healthspan and suit your specific needs.
Written by Kelsey Costa, MS, RDN on September 9, 2024 — Fact checked by Jill Seladi-Schulman, Ph.D.
Image by Jan Mateboer from Pixabay
