ISLAMABAD: Previous research shows that what we eat and following certain diets can have a positive impact on the aging process and how long we live.
A recent investigation utilizing a mouse model has revealed that while consuming fewer calories may contribute to a longer lifespan, those that lived the longest lost the least weight on a calorie-restricted diet. Researchers have also noted that specific genetic factors might have a more significant influence on longevity than diet itself. Previous studies indicate that our dietary choices can affect the aging process and our lifespan.Healthcare in Crisis: Male Doctors Flee, Women Opt-Out, Warns PIMA
Various diets, including the Mediterranean diet, intermittent fasting, and caloric restriction, have been shown to promote longevity. Recently, scientists from The Jackson Laboratory in Bar Harbor, ME, and Calico Life Sciences in South San Francisco, CA, discovered through a mouse model that while lower calorie intake could help increase lifespan, the mice that lived the longest lost the least weight on a restricted-calorie diet.
In a new study published in the journal Nature, researchers also identified certain genetic traits, such as genetically encoded resilience, that may have a more substantial impact on lifespan than dietary habits.
Investigating Caloric Restriction and Intermittent Fasting
In this research, 960 genetically diverse female mice were assigned to five different dietary regimens:
• Caloric intake limited to 60% or 80% of baseline daily calories
• Fasting for one or two consecutive days each week without caloric restrictions
• Free access to food at any time
“We aimed to determine if lifespan-extending strategies like caloric restriction or intermittent fasting could be advantageous for everyone or just specific individuals. This is challenging to assess in humans, so we opted for a genetically varied mouse model,” explained Gary Churchill, PhD, Karl Gunnar Johansson Chair and professor at The Jackson Laboratory and the senior author of this study, to Medical News.
Caloric restriction has been known to prolong lifespan in rodents since its identification in rats in the 1930s, though the underlying mechanisms remain unclear, noted Andrea Di Francesco, PhD, principal scientist at Calico Life Sciences LLC and lead author of this study. “Recent findings indicate that the timing of feeding is crucial in addition to decreased caloric consumption. Additionally, recent research suggests that some mouse genotypes may have a shortened lifespan under caloric restriction. We sought to understand how universally effective lifespan extension through caloric restriction is and whether the benefits vary depending on the degree of caloric restriction (20% vs. 40%),” Di Francesco added.
Extended Lifespan in Calorie-Restricted Mice
By the end of the study, researchers found that mice with unrestricted access to food lived an average of 25 months, while those on intermittent fasting diets had an average lifespan of 28 months. Mice on caloric restriction enjoyed the longest lifespans, with those consuming 80% of their baseline calories living an average of 30 months, and those on a 60% calorie intake surviving an average of 34 months.
“We were astonished that the significant (40%) caloric restriction led to such a notable lifespan increase without any evidence of reduced lifespan in any of the mice. We expected that in a genetically diverse population — a distinctive aspect of our study — some mice would have shorter lifespans under 40% caloric restriction or a two-day intermittent fasting schedule,” Churchill remarked.
Weight Loss May Not Enhance Longevity
Researchers also found that genetic factors — such as genetically encoded resilience — played a larger role in lifespan than diet in the mouse model. “In mouse studies where we control the environment, we observe a substantial genetic influence. Genetics provides a ‘benchmark’ for evaluating the effectiveness of different diets. Despite the significant lifespan extension observed (e.g., with 40% caloric restriction), there remains considerable individual variability (both genetic and random). In other words, diets are not panaceas — they may increase average lifespan but do not ensure a long life for every individual. Other factors are equally important for lifespan,” Di Francesco explained.
Scientists noted that mice that maintained consistent body weight, body fat percentage, and immune cell health during periods of reduced food intake and stress, as well as those that did not lose body fat later in life, had the longest lifespans.
It has been suggested that caloric restriction may extend lifespan by mitigating obesity and prediabetes traits in mice. Enhancing metabolic health is vital for humans in contemporary societies, leading to the assumption that lifespan extension in mice might stem from reducing obesity and its adverse health impacts, Churchill mentioned.
However, this does not appear to be the case — lifespan extension was more pronounced in mice that maintained higher body weight. While weight loss is typically viewed as beneficial from a human standpoint, it does not inherently lead to increased lifespan; they are separate outcomes of caloric restriction,” he concluded.
