Eating Fewer Calories Can Slow Down Aging
Via. NPR
Slowing human aging has reached the pinnacle of scientific research in the 21st century. As our understanding of the inner workings of the human body deepens, the avenue to longevity only widens. One aspect of age reversal that science has unraveled is the effects of calorie consumption on aging. It was always widely established that eating certain kinds of food was better for longevity than other kinds; however, science has found that eating simply less contributes to longevity as well. Is it that simple, though? And does it mean you should cut down your calorie intake to 1,500 calories a day if you want to live longer?
In 1991, eight volunteers sealed themselves into a large greenhouse in the desert near Tucson, Arizona. They were part of an experiment attempting to discover whether a carefully managed selection of plants and animals could develop into a self-sustaining ecosystem, which they labeled “Biosphere 2.” For the two years they were inside Biosphere 2, the volunteers consumed a low-calorie, nutrient-dense diet of vegetables, fruits, nuts, grains, and legumes with small amounts of dairy, eggs, and meat. This totaled to a daily intake of only 1,750-2,100 calories, nearing half of the average American’s daily intake of 3,540 calories. Soon, the biospherians, lean to begin with, slimmed down. However, after eight months, their weight stabilized. Despite being gaunt, their energy levels remained high, and their blood tests showed physiological responses corresponding to those of calorie-restricted rodents with extended lifespans. This result provoked an interest in finding what eating fewer calories really has to offer for longevity.
To understand the effects of caloric restriction on longevity, we must first understand what calories are. Calories are a measure of the amount of energy cells can get from breaking food into its basic chemical components. Looking at only this, eating more calories may seem better for living longer and healthier, as more calories will equate to more energy for the cells. However, a closer look suggests otherwise. The breaking down of the food consumed and what happens with the consequent components are handled by a range of signaling pathways, whose job is matching what the cell is doing with how much energy the organism needs and has available. Malfunction in these nutrient-signaling pathways is a crucial mark of aging.
A general truth behind caloric restriction is that when energy—derived from consumed calories—is scarce, the nutrient-signaling pathways in cells pay greater attention to what is happening and keep the cell in better shape. A 2022 study in mice led by neuroscientists at UT Southwestern’s Peter O’Donnell Jr. Brain Institute corroborated this: researchers compared the lifespans of a group of mice fed without constraint and another group of mice fed restrictively. Their findings showed that mice that ate as much and whenever they wanted lived nearly 800 days, an average lifespan for their species. However, mice whose calorie intake was restricted lived for 875 days, a 10% increase in their lifespan. A counterintuitive yet important aspect of the study is that the body weight of the mice was not affected by the eating pattern—there were no differences in body weight between mice in the two groups despite the considerable difference in their calorie intake.
These findings have stirred longevity enthusiasts to off-label prescriptions that were found to lengthen the lives of lab animals. A popular example is rapamycin, which, when taken late in life, increases lifespan by 9-14%, equating to more than seven years of human life. Imagine a pill that adds nearly a decade to your life—it sounds incredulous, but it already exists. It works by upregulating the rate at which cells break down damaged internal structures—autophagy—which is the same impact that consuming less food will have. It also influences the balance of the body’s protein content—a process known as proteostasis—and the reproduction of the mitochondria. All of these effects have been found to be vital biomarkers of longevity. However, there are side effects to the use of rapamycin, primarily anemia and insulin insensitivity, making it ill-suited for widespread use. Developing adequate medicine to make eating less for longevity the least uncomfortable is yet to be developed, however, and large corporations are feeling the weight of a fortune heading their way.
Humans have always pursued longevity—what human would not want to live longer, even just a few years? And now that we live free from continuous threats that our primal ancestors had struggled with, coupled with the unprecedented development of modern medicine, this desire has only heightened. For now, eating less to live more seems to be viewed as a favorable tradeoff by many.