In my previous article I discussed with you the life quality benefits that can be realized through the application of a regimen of regular exercise in your lifestyle. In this article, we will discuss recent studies that delve deeper into the system wide changes wrought by regular exercise, and show that exercise actually mimics gene expression associated with caloric restriction.

In a myriad of species, (spiders, rats, Fish) calorie restriction has been shown to increase longevity. (1) The mechanisms that produce this increase of life span in these creatures are thought to be the accumulated effects of a wide array of genes that are turned on by the environmental stressor of calorie restriction. However, the benefits of calorie restriction lose their luster when applied to humans. It is thought (though it has never been studied scientifically) that the same array of gene expression will be evinced in humans that partake of a calorie restricted diet, but the sacrifices attendant with a calorie restricted diet appear unacceptable when measured against the meager lifespan gain. (1)

Miranda Hitti writes:
“It’s long been known that rats live much longer than normal on extremely low-calorie diets.” You can practically double their lifespan,” says researcher John Phelan, PhD, in a news release.

”The same result has been found in fish, spiders, and many other species,” he continues. ”If it works for them, some thought, it should work for us; I’m here to tell you it doesn’t.”

Phelan is an evolutionary biologist at UCLA. He and his colleagues crunched numbers from rat and human longevity studies.

Their bottom line: Severely cutting calories might extend human life a little bit, but not much, and the sacrifice likely wouldn’t be worth it. The report appears in Ageing Research Reviews.

Not Your Average Diet
The researchers aren’t writing about cutting out a bonbon here or there or making diets a bit leaner. Instead, rats in longevity studies got so few calories that they could no longer reproduce. The rats simply didn’t have enough energy to breed and rear the next generation. That saved the rats a lot of effort. Without the wear and tear of parenting, their bodies got a break, and they lived longer. But people are different. They don’t give birth to litters of babies per pregnancy or reproduce as often as rats. So even if someone starved themselves enough to shut down fertility—and stayed that way throughout adulthood—they wouldn’t live much longer than their well-fed peers, Phelan’s team reasoned.

Researcher: ‘Payoffs Are Not Worth It’
”To undergo decades of calorie restriction, suffering chronically reduced fertility and increased hunger, for the sake of a much smaller proportionate increase in longevity than is seen in rodents seems unappealing and ill-advised,” write the researchers. “¹

Although, for the sake of practicality (not to mention comfort), calorie restriction is not a viable approach to longevity and quality of life, exercise is. The biological methods that are utilized through caloric restriction, namely gene expression and the cascading effects of these newly activated genes on the body are in large part mimicked by long term, sustained physical activity (exercise). ² For instance, SREBP gene expression (genes responsible for insulin resistance and the bio synthesis of triglycerides and fatty acids) is activated through both exercise and calorie restriction. ²

The SREBP series of gene expression is just one of a myriad of duplicate gene expressions shared by caloric restriction and regular (at least 3 times a week) exercise. Given the extreme stress of living within the calorie restriction lifestyle, the relatively easy to live with regimen of regular exercise is an easy choice to achieve both quality of life and longevity associated with beneficent results through exercise.

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Sources:
¹Extremely Low-Calorie Diet Won’t Extend Life
Researchers Say Severely Cutting Calories Helps Rats Live Longer, but Not Humans
By Miranda Hitti / WebMD Medical News.

²Exercise training and calorie restriction increase SREBP-1 expression and intramuscular triglyceride in skeletal muscle

Kristen J. Nadeau,1 Lindsay B. Ehlers,1 Lina E. Aguirre,2 Russell L. Moore,3 Korinne N. Jew,3 Heidi K. Ortmeyer,4,5 Barbara C. Hansen,6 Jane E. B. Reusch,2,7 and Boris Draznin2,7
1Division of Pediatric Endocrinology, Department of Pediatrics, University of Colorado Health Sciences Center; 2Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Health Sciences Center, Denver; 3Department of Integrative Physiology, University of Colorado, Boulder, Colorado; 4Geriatric Research, Education and Clinical Center, Baltimore Veterans Affairs Health Care Center; 5Departments of Medicine and Physiology, University of Maryland School of Medicine, Baltimore, Maryland; 6Departments of Internal Medicine and Pediatrics, University of South Florida, College of Medicine, Tampa, Florida; and 7Veterans Affairs Research Service, Denver Veterans Affairs Medical Center, Denver, Colorado

Submitted 9 November 2005; accepted in final form 26 January 2006.

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