Does Calorie Restriction Extend Lifespan?

The relationship between calorie restriction and longevity has been a popular and controversial topic both in the lay press and scientific press for quite some time now. Before you drastically reduce your calories in hopes of adding years onto your life, you need to know all of the facts about this issue.

Calorie restriction (CR) is where you reduce daily calories by 30-50% in order to slow down your metabolism. Part of the idea behind CR is that if you slow down your metabolism, you allegedly slow down aging. The objective is to get very thin so that your smaller body doesn’t need many calories any more.

The biological mechanisms of potential lifespan extension through CR are not fully understood, but researchers say that in addition to changes in metabolism, it may also involve factors such as reduced oxidative damage, improvements in insulin sensitivity, and reduction of glycation.

Mouse studies on CR go back as far as 1935, monkey studies began in the late 1980’s, and humans have been experimenting with CR for some time. So far, the results are clear on one thing: restricting calories does increase lifespan in rodents and other lower species (yeast, worms and flies). Studies suggest the life of the laboratory rat is 25% longer with CR (even longer with aggressive CR). In primates and humans, biomarkers of aging show signs of slower aging with CR. Many CR proponents feel that these studies and results prove that CR extends lifespan in humans.

The truth is, there's no direct experimental evidence that humans will live longer from practicing CR. Due to the length of human lifespans, we will not have the necessary data for at least another generation, and perhaps multiple generations. Even then, it will still be highly speculative whether CR will extend human life at all, and if so, by how much.

Many experts are skepitical about calorie restriction. Jay Phelan, a biologist at UCLA, says: "There is no current evidence that lifelong caloric restriction leads to increased lifespan in primates. It's certainly tantalizing that things like blood pressure or heart rate look as though they're a lot healthier, and I believe they are. Whether or not this translates to a significantly increased lifespan, I don't know. I predict that it doesn't."

While some CR proponents claim that they don't get hungry and cite studies suggesting that hunger decreases during starvation, researchers say that hunger remains a big problem during CR, and that alone makes CR impractical.

Personally speaking, the CR advocates that I've seen don't look very healthy. They look gaunt and have little or no muscle mass. Until more is learned about the relationship between calorie restriction and longevity, I won't consider making it a part of my lifestyle. I'll continue doing what I do now - following a nutrition program that provides me with enough calories and energy to fuel my workouts and active lifestyle, helps me build and maintain lean muscle mass, and doesn't leave me feeling constantly hungry.

If that sounds like the type of nutrition program you would like to follow, Burn The Fat, Feed The Muscle will show you how to develop just such a program.

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