You’ve probably seen countless pills, potions, and headlines promising to help you unlock, unleash, or otherwise master your metabolism, as though it were some magical, flab-frying gremlin you can order to toss more fat cells into the fire. But it’s not quite like that. Your metabolism isn’t even a “thing;” it’s a process. Let’s break it down.
What is Your Metabolism?
“Metabolism” is an umbrella term for a host of chemical reactions going on inside you every moment of every day. It’s what changes the food you eat and the fuel stores you have into usable energy. It’s what breaks down and rebuilds muscle tissue after a hard run. It’s what keeps you living, breathing, and thinking.
The reason so many people are interested in it is because the higher your metabolism, the more calories you burn, and the easier it is to lose or maintain weight. Despite the hype, there are no real “secrets” or magic bullets for blasting fat in your sleep, but there are some scientifically-sound ways to maximize your energy-burning metabolism and to keep it humming along on all cylinders as you age.
Metabolism by the Numbers
When you talk about metabolism, you’re referring to your resting metabolic rate (RMR), the calories you burn doing nothing more strenuous than sitting and scrolling through this story. RMR accounts for 60 to 75 percent of your total calorie burn (the rest comes in the form of daily activity and digestion) and varies from person to person.
“Bigger people have higher metabolisms than smaller people, so do muscular people. Men tend to use more energy than women. Hormones and age influence it. Some people just genetically idle at a higher rate,” says Polly de Mille, R.N., an exercise physiologist at the Women’s Sports Medicine Center at the Hospital for Special Surgery in New York City.
On average, the RMR is around 1400 calories for women and 1800 for men. Unless you take action (literally), your RMR declines about 2 to 3 percent per decade during adulthood, says Brian St. Pierre, R.D., a certified strength and conditioning specialist and director of performance nutrition at Precision Nutrition. That doesn’t sound like a lot, but it adds up quickly, and you could be looking at burning 200 to 300 fewer calories every day by the time you hit later adulthood.
The good news is that you don’t have to be at the mercy of this gradual metabolic meltdown, de Mille says. “Your RMR isn’t set in stone. Your lifestyle has a big influence. You can slow down age-related decline and even raise your RMR by as much as 15 percent, depending on where you start.” Here’s how to boost your metabolism—according to science.
This is a biggie for weight-conscious runners. It’s tempting to cut calories while you’re training to drop weight, but cutting too much can backfire and effectively slow down your metabolism. Because your body doesn’t have enough energy to fuel your runs, repair from your workouts, and keep all its systems running optimally, it goes into conservation mode, and your metabolic rate drops.
“Runners, especially distance runners, are always riding that razor’s edge where they’re training hard, and everything is humming ” de Mille says. But when everything starts to slow down, there’s a name for it: Relative Energy Deficiency in Sport (RED-S), a syndrome that used to be deemed the “female athlete triad,” until researchers realized that men suffer from it in equal numbers.
“It’s a product of too much training without the fuel to support it,” de Mille says. Your performance generally slides at this point, as you can experience a cascade of negative symptoms such as decreased training response, reduced strength and endurance, weight fluctuations, low mood, and loss of menstruation in women.
How to Calculate Your Numbers:
To put enough energy in, you have to know how much energy you’re using. The only true way to measure RMR is in a lab, de Mille says. “But the following formula (The Harris Benedict Equation) comes close. “I’m always impressed by how close the equation is to the measurements I do in the lab.” Just pop in your weight and height.
Women: BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)
Men: BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in year)
Or use this handy online calculator
For a good ballpark of your total daily calorie burn, add in your activity level. Multiply your BMR by the following, depending on how much running and other activity you do.
1.2 = sedentary (little or no exercise)
1.375 = lightly active (light easy runs 1-3 days/week)
1.55 = moderately active (recreational spirited running 3-5 days/week)
1.725 = very active (training, running, and/or racing 6-7 days a week)
1.9 = extremely active (racing, hard running, and physical job)
Once you have your total daily calorie burn, take in at least that many calories each day or slightly less if you are trying to lose weight. This will ensure you’re putting enough logs on the fire that is your metabolism to keep it burning strong.
Crank Up the Intensity
In one study, researchers measured the metabolism in exercisers after a hard 45-minute cycling session at 70 – 75 percent VO2 max, where they burned about 520 calories (the equivalent of a 40-minute run at a 7:30 pace) and then again on a rest day. They found that the volunteer’s metabolisms stayed elevated for 14 hours, burning 37 percent more calories (190 total) after the hard sweat session compared to what they burned on the rest day.
Running intervals, because there is more impact and greater muscle damage than in cycling, may also have the benefit of giving you a metabolic bump, de Mille says. “You need a little more repair afterwards.” Try these high-intensity interval drills on your next run or blast through a series of HIIT sessions to boost your strength and prevent injury with the IronStrength Workout.
“Muscle burns more calories at rest than fat—four to six calories per pound versus two calories per pound per day,” St. Pierre says.
So hit the weight room. “Runners may think they’re maintaining muscle by running hills and doing hard workouts, but the only real way to build or maintain muscle is to work it to absolute fatigue, which means strength training,” de Mille says.
And don’t worry about getting huge. You can build all the strength you want without the hypertrophy (bulk) you don’t by lifting fewer sets at a heavy weight. A recent study comparing exercisers performing multiple sets of seven moves for more than an hour in the gym to another group doing just one set of each move, taking only 13 minutes, found that the one-set group gained just as much strength as their multiple-set performing peers, but only the high volume lifters put on significant muscle mass.
Change It Up
Long term, running can help keep your metabolic rate high. Research finds that highly-trained runners who stop running see their resting metabolic rate dip by about 7 to 10 percent. That said, the more you do the same thing, whether it be your usual five-mile training loop or kettlebell circuit, the more efficient your body becomes, the less energy it takes to perform the task. So for the best results, make it a point to change up your routine from time to time.
Efficiency is valuable from a competitive standpoint because it allows you to go harder and longer at a faster pace, St. Pierre says. “But it’s valuable from a metabolic standpoint to perform varying types of training to provide different variables for your body to adapt to. This is part of why coaches employ periodization and different training blocks in athlete’s programs.”
Regular running and gym workouts help keep your metabolism motoring along, but if you spend the other 12 hours of the day planted on your posterior, your metabolic rate slides, and you could end up no leaner or healthier than your sedentary counterparts. It’s called being an “active couch potato.” One study of 168 men and women reported that regardless of how much (or how little) moderate to vigorous exercise the volunteers did, those who took more breaks from sitting had slimmer waists, lower BMIs, and healthier blood fat and blood sugar levels than those who sat the most. More striking, researchers at The University of Missouri found that non-exercisers who spent little time sitting burned more calories than folks who ran 35 miles a week but were otherwise sedentary.
Interrupt your sedentary time as often as possible. Stand up every half hour if you can. If you have to sit for longer, take a longer, more active break and get up and move around for a few minutes before you sit back down. Taking every opportunity to just get up and move will have a big impact on your overall health.
Dial in Your Diet
Eating plenty of protein is the best way to give your metabolism a diet-related bump. Protein not only helps you build and maintain metabolism-revving muscle tissue, but it also temporarily increases your metabolism after you eat it. Research shows that protein causes the largest rise in the thermic effect of food (TEF), the energy you burn during digestion, which accounts for about 10 percent of your daily energy expenditure. Protein-rich food increases your metabolic rate by 15 to 30 percent, compared to a rise of 5 to 10 percent following carbohydrates, and a 0 to 3 percent bump after eating fat. Aim for 30 grams of protein at each meal.
Other commonly recommended metabolism-revving foods and drinks, including green, white, and oolong tea, hot peppers, and coffee aren’t metabolic miracle workers, but may increase metabolism up to 5 percent, according to research. If you enjoy them, it’s worthwhile to include them in your daily diet, de Mille says. “Sure it might just be 5 or 10 calories, but it all adds up over time,” she says.
Interestingly, green tea appears to amplify the metabolism-boosting effects of resistance training. In a study of 36 women, those who drank green tea and followed a resistance training program for eight weeks enjoyed a significant increase in RMR and lean body mass and a decrease in body fat and waist circumference, compared to those who did neither or either by themselves, who saw little to no increases in RMR or even RMR decreases.
Drink Water Daily
As a runner, you need to stay hydrated to perform your best. Research also shows drinking water is good for your metabolism. One study found that metabolism rises about 24 percent for an hour after you down a pint of water. For the best metabolic-boost, opt for ice water: Your body burns energy warming it to body temperature.
Not all fat is slothful. We all have a bit of metabolically active fat known as brown fat that helps regulate our temperature and keep us warm when it’s cold out. Keeping your thermostat turned down and exercising in chilly temps can significantly increase your RMR, according to research.