Do you sometimes wish your metabolism were under your control, and you could turn a knob to speed it up? Most people would like to give their metabolism a kick-start, so they can eat more of their favorite foods. Certainly, it would feel good to indulge in high-calorie treats and not have them show up on your hips and waistline. But having a super-fast metabolism may have some downsides if you hope to make it to a ripe, old age. Having a slower metabolic rate has been linked with greater longevity in animals and in some small human studies too. This means a faster metabolism could work against you from a longevity standpoint.
Slower Metabolism: A Recipe for Longevity?
The master gland for regulating metabolism is the thyroid gland. The thyroid releases two hormones called T3 and T4. Together these two hormones determine the body’s metabolic rate. Not surprisingly, people who have low levels of these hormones are prone to weight gain as well as a host of other symptoms.
According to a study published in the Journal of Clinical Endocrinology and Metabolism, lower levels of T3 and T4 are linked with greater longevity. Researchers looked at 421 Dutch families with exceptional longevity. They found the siblings of these families had lower levels of thyroid hormones in their bloodstream. Medically, it’s a common practice to supplement older people who have even marginally low levels of thyroid hormone. Now some experts are questioning whether this practice could be shortening their lifespan.
Another study published in the Journal of Clinical Endocrinology in 2010 followed a group of study participants for almost 15 years. They found their mortality rates rose between 23% and 28% for every 100-calorie increase in their resting metabolic rate. Other human research, as well as animal research, also supports the link between higher resting metabolic rates and decreased longevity.
The Role of Free Radicals in Longevity
Although research on this topic is preliminary, there are some compelling reasons why higher metabolic rates could be linked with a shorter lifespan. When food is converted to energy, more cell-damaging free radicals are formed. These free radicals can damage healthy organs and tissues. Free radicals may also explain why calorie-restriction in animal species prolongs their lifespan. The less food an animal eats the fewer free radicals that are formed.
Exercise, Metabolism, and Longevity
If a faster metabolic rate is linked with mortality, you might wonder why exercise isn’t harmful too. After all, exercise boosts your metabolic rate for variable periods of time both during and after exercise. But, according to experts, you don’t have to put away your exercise shoes. Exercise-induced rises in energy expenditure are still associated with increased, not decreased, longevity. Although exercise increases free radical production in the short-term, the body adapts to these free radicals. When it does, it becomes even better at protecting itself against their damaging effects by producing more cell protective antioxidant enzymes.
Of course, it may be possible to overwhelm the body’s ability to deal with exercise-induced free radicals. There’s some question as to whether people who run ultra-marathons or log 100 or more miles of running a week may be harming themselves. The verdict is still out. But moderate amounts of exercise are still your best defense against aging and early mortality.
Metabolism and Longevity: The Bottom Line?
Having a super-fast metabolism may have short-term benefits by allowing you to eat more of what you want without gaining weight, but it may shorten your lifespan as well. Stay healthy with moderate exercise and a diet rich in fruits and vegetables. They’re one of the best sources of natural antioxidants that keep your cells healthy.
References:
J Nutr. 2002 Jun;132(6 Suppl 2):1583S-97S.
J Clin Endocrinol Metab. 2011 Jun;96(6):E972-6. Epub 2011 Mar 30.
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