The largest component of our daily energy budget is resting metabolic rate. The direct effects of physical activity are relatively small compared to how many calories we expend just living and breathing. Now, during something like training for the US Army’s Special Ops or climbing a four-mile-high mountain, we may burn 4,000 calories a day. For most people, however, the calories we burn just lying around existing exceeds normal physical activities. Thus, our resting metabolic rate can have implications for controlling our weight.
Researchers have shown that dietary nitrate found in beets and green leafy vegetables improves the efficiency of the little power plants within our cells, boosting athletic performance by extracting more energy from every breath. So, if we eat a lot of vegetables, might it slow our metabolism since our body can function so much more efficiently with the calories we give it?
Indeed, researchers found that after giving people a dose of nitrate equivalent to a few servings of spinach or beets, their resting metabolic rates slowed on average about 4 percent. That’s nearly a hundred calories a day. If our bodies burned that many fewer calories each yet we didn’t eat any less, we could put on a few pounds. Of course, green leafy vegetables may be the healthiest food on the planet, so we shouldn’t decrease our greens intake to try to control our weight. So what’s going on? Researchers think perhaps it was a way our body evolved to use vegetables to help preserve energy during lean times in our ancient past. That is, slowing our metabolism may have benefits for our longevity.
What else similarly slows our metabolism? Caloric restriction, such as eating every other day. This may be one reason why caloric restriction is associated with a longer lifespan in many animals. Maybe like a candle, burning with a smaller flame allows us to last longer. It’s hard to walk around starving all the time, but it’s easy to replicate that same metabolic benefit by eating a big salad every day.
This may be why eating leafy green vegetables is among the six most powerful things we can do to live longer, along with not smoking, not drinking heavily, walking at least an hour a day, getting seven hours of sleep a day, and achieving an ideal weight. Doing even just one of these six may cut our risk of premature death by around 20 to 25 percent.
Michael Greger, M.D.
PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations—2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet, and my latest, 2016: How Not to Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers.
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