Skipping meals or going on extreme cleanses
Missing out on essential nutrients, especially protein, turns your metabolism sluggish, says registered dietitian Joan Salge Blake, a clinical associate professor at Boston University's Sargent College of Health and Rehabilitation Sciences and a spokesperson for the Academy of Nutrition and Dietetics. It's okay for a few days, but after that, your body switches into "starvation mode," thinking that it needs to store, not burn, fat to keep you alive. That's why fasting isn't a smart idea. The same goes for any crazy diets that encourage you to consume nothing but liquids for more than three days. "When you don't get enough protein, your body breaks down lean muscle mass, which is what slows your metabolism," says Blake.
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Bad news for the corporate set. "Even if you go to the gym for a half hour every day, if you sit at a desk for eight hours, you still have a sedentary lifestyle," says Blake. To avoid losing metabolism-boosting muscle mass, which happens when you don't move major muscle groups throughout the day, think about downloading a movement tracking app or buying a gadget like a Fitbit or Jawbone, which alerts you when you've been sitting still for most of the day. Sometimes, that's enough to encourage you to spend half of your lunch hour on a walk, not in the break room.
Skimping on sleep
Not getting enough zzz's can negatively impact your fat cells, according to a recent study from the University of Chicago Medicine. Researchers found that sleeping for 4.5 rather than 8.5 hours a night reduces the ability of fat cells to respond to insulin (a hormone that regulates energy) by 30 percent. "While you're probably getting more than 4.5 hours of sleep per night, you may not be getting 8 hours, and the further you drop below that, the more likely you'll experience carb cravings, which can lead to weight gain," says Matthew Brady, Ph.D., who coauthored the study.
Having your period
When you lose blood each month, you also lose iron, the mineral that helps deliver oxygen to your muscles. And if you're iron-deficient, your metabolism may sag, according to registered dietitian Tammy Lakatos Shames, author of Fire Up Your Metabolism: 9 Proven Principles for Burning Fat and Losing Weight Forever. To ward off the problem, fill your plate with iron-rich foods like spinach, beans, shellfish, lean beef, raisins, and artichokes--especially when it's that time of the month.
When you down a drink, be it wine, beer, or liquor, your body has to break down that alcohol before it can get to all the calories that you scarfed down earlier in the day. That slows down the metabolic process, so it's a good idea to limit yourself to one boozy beverage a day.
A report from the University of Utah College of Medicine showed that people who drank eight to 12 glasses of water every day burned calories faster than people who drank less water. Carry a bottle around with you so you don't forget to sip throughout the day.
Researchers at the Nutrition Institute at the University of Tennessee at Knoxville have found that the more calcium you consume, the more fat you burn. Good sources include milk, reduced-fat cheese, yogurt, and dark leafy greens--all of which have tons of other health benefits, too.
Not drinking coffee or tea
Caffeine can stimulate your metabolism for a few hours after consumption, according to research published in the American Journal of Clinical Nutrition. So consider this not just permission but encouragement to start off your day with a java or tea fix.
Doing only cardio
Running, biking, swimming, and rowing get your heart pumping, making them super-important for boosting your metabolism. But if you're not incorporating strength training into your regular routine, you're missing out on a double whammy. The more muscle you build, the more calories your body will burn, so grab some hand weights, do resistance training using your body weight (i.e., push-ups, lunges, and squats), or ask a trainer to show you how to best use some machines at the gym.
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