But there are easy things you can do to stoke your fat-burning potential. "There's no reason you can't have the same metabolism in your 30s and 40s that you had in your 20s," stresses Pamela Peeke, M.D., author of Fight Fat After Forty. Here are some experts' tips on how to boost your metabolism — so you, too, can guiltlessly binge on Ben & Jerry's every now and then.
In a small German study, subjects who drank 16 ounces of water at a time experienced a 30 percent increase in metabolic rate during the following hour, burning an extra 24 calories. The researchers recommend cool water because the body expends extra calories warming it up to your body temperature. Water's not the only healthy drink. We sipped our way through dozens of smoothies, teas, and juices to find this list of the most delicious and nutritious liquids.
The theory makes sense: Your body burns carbs for energy, but if you eat them before you go to sleep, your body just stores them as fat. One study in the European Journal of Nutrition put two groups of men on identical weight loss diets. The only difference? Half of the group ate their carbs throughout the day while the second group reserved carbohydrates for nighttime. The result? The nighttime carb group showed a significantly higher diet-induced thermogenesis (meaning they burned more calories digesting their food the next day). Moreover, the daytime-carb group showed increased blood sugar levels.
Load up on low-fat dairy: Women who consumed milk, yogurt, and cheese three to four times a day lost 70 percent more body fat than women who didn't eat dairy in a study published in the January 2003 American Society for Nutritional Sciences Journal of Nutrition. The reason: Calcium, along with other substances in dairy, actually revs up your metabolism, telling your body to burn excess fat faster, according to study author Michael Zemel, Ph.D., director of the Nutrition Institute at the University of Tennessee in Knoxville. And no, fortified o.j. won't do the trick. The best results come from dairy products instead of from other calcium-rich foods (like broccoli), calcium-fortified products (such as orange juice) or supplements. Women reap the largest fat-burning benefit when they consume three servings of dairy and 1,200 milligrams of calcium a day, Zemel's research shows.
Eat six small meals a day to avoid blood-sugar spikes and minimize urges to binge. Try to schedule meals at the same time each day. If you feed yourself well throughout the day, you'll learn to understand when your body truly needs food. You can't starve yourself and expect to make good choices at the next meal. Need a few healthy lunch ideas? Check out these top food swaps from a nutritionist.
Spreading your meals throughout the day might keep you from getting too hungry and overeating. If so, it is a good idea. Athletes perform better when they eat more often in smaller amounts. If you are someone who has a hard time stopping once you start eating, 3 meals a day may make it easier for you to stick to an appropriate intake than lots of little snacks.
Caffeine may provide a bit of a boost to the metabolism, especially when ingested before exercise, but no amount of metabolic boost can burn off the empty calories that energy drinks supply. According to one study published in Mayo Clinic Proceedings, a typical energy drink serves up a quarter cup of sugar—calories that hit your body all at once and trigger fat storage. If you want to burn calories, try the miracle beverage known as tap water. According to a study published in The Journal of Clinical Endocrinology and Metabolism, after drinking two tall glasses of water (17 ounces), participants’ metabolic rates increased by 30 percent.
"Protein burns more calories than carbs and fat,” says Bustillo. About 30 percent of the calories in protein will go towards digestion and absorption, whereas that number is only about 10 percent for carbs, and even less for fats. Fiber's another nutrient that costs a little more energy, says Bustillo—so, getting adequate protein and fiber can definitely help maximize your BMR.
Why does eating lots of fish rich in omega-3 fatty acids (salmon, herring, and tuna) help amp up metabolism? Omega-3s balance blood sugar and reduce inflammation, helping to regulate metabolism. They may also reduce resistance to the hormone leptin, which researchers have linked to how fast fat is burned. A study in Obesity Research found rats that ingested large doses of fish oil while exercising lost weight. Take omega-3 fatty acid supplements; Hyman recommends 1,000 to 2,000 milligrams per day. Hate the fishy after-burp? Try flaxseed oil, walnuts, or eggs fortified with omega-3s. Or check out supplements (by brands such as Nordic Naturals) that have no fishy taste.
You’ve heard they're bad for you. But trans fats also slow down your body's ability to burn fat. "They have an altered shape and make your biochemistry run funny," Hyman says, explaining that trans fat binds to fat and liver cells and slows metabolism. Eating trans fat can also lead to insulin resistance and inflammation, both of which cripple metabolism and can cause weight gain.
Even when you’re at rest, your body is constantly burning calories. In fact, 75 percent of the calories that you burn each day are being used up just keeping you alive. “Resting metabolic rate” is much higher in people with more muscle, because every pound of muscle uses about 6 calories a day just to sustain itself. If you can pack on just five pounds of muscle and sustain it, you’ll burn the caloric equivalent of three pounds of fat over the course of a year.
Research shows that getting plenty of protein can boost your metabolism, causing you to burn an extra 150 to 200 calories a day, says Jeff Hampl, Ph.D., R.D., a spokesman for the American Dietetic Association. "Protein is made up mainly of amino acids, which are harder for your body to break down [than fat and carbs], so you burn more calories getting rid of them," he explains.
A striking new study published in the journal Diabetes suggests that simply turning on the AC may subtly transform a person’s stores of brown fat, the “good” fat stimulated by cold temperatures, that serves to keep us warm by burning through “bad” fat stores. Participants spent a few weeks sleeping in bedrooms with varying temperatures: a neutral 75 degrees, a cool 66 degrees, and a balmy 81 degrees. After four weeks of sleeping at 66 degrees, the men had almost doubled their volumes of brown fat. Cool!
While going on a diet or purchasing the latest weight-loss products might seem like a quick way to shed pounds, you might not get the results you hoped for if you don't take your metabolism into account. Dieters might count fats, carbs, and calories meticulously, but in order to lose weight successfully, you have to understand your metabolism and what it does for your body.
The smoothie revolution is here, and lots of people are swilling down bushels of leafy greens. Believe it or not, there’s a downside to this ingenious delivery method. A big part of the body’s job—breaking down food so that the body can absorb nutrients—has been outsourced to our Nutribullets and Vitamixes. That means that the body is expending much less energy than it would if we were eating kale, spinach, and bananas in their solid form. Smoothies are great for weight loss, but by prioritizing lean meats, fish, fibrous vegetables and fruit, you are driving up TEF (the Thermic Effect of Food, or your metabolic rate after eating) and expending more calories on digestion.
It's one of the most frustrating realities of dieting—if you cut out too many calories, your metabolism thinks times are lean and puts the breaks on fat-burning to conserve energy, Hunter explains. Here’s the trick to keeping your metabolism revved up while dieting: Eat enough calories to at least match your resting metabolic rate (what you'd burn if you stayed in bed all day; calculate yours here). That's about 1,330 calories for a 5-feet-4-inch, 150-pound, 40-year-old woman.
Going organic can be costly and leave a dent on your wallet, but it can speed up your metabolism. The antibiotics and growth hormones found in conventionally farmed foods could hamper your immune system and slow down metabolism. The amount of pesticides in non-organic foods can cause a above normal dip in metabolism in dieters who begin to lose weight, says Prevention.com.