Good Mood, Better Metabolism
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A fast metabolism, a happy outlook—these are two things we can all agree are worth chasing. And now, scientists are realizing that going after one may naturally deliver both.
What we know for sure: The key to this connection is the hunger hormone leptin, which tells your brain that you feel full. "Leptin impacts not only your food intake but your mood as well," says Paul Burghardt, Ph.D., an assistant professor of nutrition and food science at Wayne State University in Detroit. This is partly because of the hormone's relationship with dopamine, a neurotransmitter that controls happiness and motivation. Generally, when leptin levels dip, the release of dopamine increases, says Stephanie Fulton, Ph.D., an associate professor of nutrition at the University of Montreal. That's when mood starts to rise.
The following five strategies will help deliver a happy mind-body balance.
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Working out, especially running and cycling, causes your leptin levels to fall, triggering a surge of dopamine, Fulton says. "When leptin declines, it sends a signal to your body that you need to eat. That stimulates dopamine production, which in turn increases your motivation to exercise longer," Fulton explains. This response is a holdover from prehistoric times. Back then, our drive and outlook were boosted whenever hunger kicked in to set us up for success in finding food. To take full advantage of this effect, hit the road or the gym in the morning, before breakfast. Since you haven't eaten for hours, your leptin levels will already be low, and you'll be able to go longer, which may rev your metabolism even more. (Here, even more health benefits of morning workouts.)
Pump Up the Iron
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If you're deficient in this mineral, you'll be less likely to score the perks of the leptin-dopamine response. People with the lowest amounts of iron had 3.2 times higher leptin levels than others, reports the Journal of Clinical Investigation. This could even lead to leptin resistance, which occurs when leptin levels remain too high for too long; the hormone stops affecting your brain, contributing to weight gain and moodiness. Aim for about 18 mg of iron a day. (Plus, exercise and an iron-rich diet might make you smarter too.)
Find Your Funny
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Your body responds to laughter the same way it does to a short bout of moderate exercise, researchers from Loma Linda University in California discovered. They found that people's leptin levels decreased after watching a comedy film. A study from Vanderbilt University found that genuine laughter increases your metabolism by up to 20 percent, and there's plenty of evidence that it makes you happier. The trick is to laugh every day. (P.S. did you know there's such a thing as laugh yoga?)
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It's no secret that a lack of z's makes you cranky, but losing just two hours of sleep for three days can also cause your metabolism to grind to a halt, according to a 2015 study. Sleep deprivation increases your cravings for junk food, Fulton adds. "It's a cycle. You don't sleep well, so you're more stressed and crave comfort food that's high in saturated fats. This increases inflammation, worsening mood."
It's not just how much you snooze but how restorative those hours are too. Sleep interruptions are worse for your mental state than not logging enough shut-eye, the journal Sleep reports. Invest in blackout curtains and a white-noise machine, and dim the brightness of your phone to tone down the sleep-sapping blue light. (Seriously, your before-bed scrolling habit could be wrecking your metabolism.)
Eat Better Fats
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Replacing saturated fat from meat and dairy with polyunsaturated and monounsaturated fats in salmon, avocados, and nuts may benefit your metabolism and your mood, research in the journal Frontiers in Neuroscience reveals. Saturated fats make you accumulate visceral fat, which slows the metabolism and produces inflammatory molecules that are linked to depression, says Fulton. Visceral fat also cranks out leptin and may increase your odds of leptin resistance. (And another study shows nuts may help boost your mood and aid weight loss.)