CAN YOU REALLY BOOST YOUR METABOLISM?
Burn calories--even while you sleep!--with a little strength training. Sounds great. But does it work?
By Amby Burfoot
Let me say right up front that I'm a big fan of strength training. Muscle is sleek and sexy, and I wish I had more. Muscle is also functional; it helps you do stuff. More muscle can help you run faster, for example, or slow down the nasty effects of aging, or get you an invite every time one of your friends needs to move heavy furniture. The problem is, strength training has been vastly oversold as a metabolism-boosting calorie burner. It's time for a reality check.
First, let's do a quick review of Metabolism 101. To lose weight, you want to increase your total calorie burn, which scientists call TEE (total energy expenditure; get ready for a parade of acronyms). To raise your TEE, you need to increase one or more of its four key parts: BMR, TEF, PAEE, and EPOC. Got that? Don't worry, I'll explain.
Your basal metabolic rate, or BMR, is essentially the calories you burn at rest. Also called resting energy expenditure, your BMR is important because it makes up a large percentage of total calorie burn, but unfortunately you can't do much about it. Your BMR is mostly determined by your genetic makeup and body weight. The only big-time way to boost your BMR is to gain weight, which will do nothing to help you wiggle into a bathing suit.
The thermic effect of feeding (TEF) is otherwise known as the energy your body expends while digesting food. The TEF is generally about 10 percent of your daily calorie burn, and can be nudged a little by eating multiple small meals, drinking more stimulant beverages (like coffee, tea, or Red Bull), consuming more chile peppers, and eating more protein.
Your physical-activity energy expenditure, or PAEE, is the sum total of your workouts, plus other activities like walking the dog, climbing stairs, and break dancing. It can be anything from zero to a substantial number, depending on whether you're more enamored of your sofa or your running shoes. Your PAEE is the most important part of your daily calorie burn, because you can actually do something about it.
The excess post-exercise oxygen consumption (EPOC) of your workout is also known as the "afterburn," that is, the extra calories you burn after exercise. It will be zero if you don't work out, and a smallish number if you do.
Now, let's return to the supposed calorie-burning benefits of strength training. We'll start with a ridiculous review of two strength-training books that was published in The New York Times last year. The Times story quoted one author, Adam Zickerman, at some length. In his book, Power of 10: The Once-a-Week Slow Motion Fitness Revolution, Zickerman says that a single 20-minute strength-training workout burns as many calories as 25 miles of running. As he told the Times: "Three extra pounds of lean muscle burns about 10,000 extra calories a month, just sitting around."
You've probably read similar claims, which often sound like this: "Every pound of new muscle burns an additional 50 to 100 calories a day." Or "Muscle burns calories even while you sleep."
If you believe any of this, you might also want to try doing long runs in your sleep. It would sure beat that damnable alarm clock buzzing on weekends. While some personal trainers promote the calorie-burning power of muscle, most reputable experts don't. In her book Ultimate Fitness: The Quest For Truth About Exercise And Health, Gina Kolata talked to Claude Bouchard, Ph.D., a world authority on virtually all things related to obesity. His response: Sorry, but muscle actually has a relatively low metabolic rate at rest.
Bouchard is likely familiar with the article "Dissecting the Energy Needs of the Body," from a 2001 issue of Current Opinion in Clinical Nutrition and Metabolic Care. This article gave me new respect for my kidneys, which burn 182 calories per day for every pound they weigh, and for my brain, which clocks in at 110 calories for every pound it weighs. But my muscles, damn them, are lazy. They burn six calories per pound, barely edging out fat's two-calorie burn. In other words, if you lose one pound of fat and replace it with one pound of muscle, your net gain in calorie burning is four calories a day. Enjoy the celery stick.
If you're interested in boosting your metabolism to lose weight, aerobic training such as running and walking (and bicycling, swimming, Nordic skiing, snow shoeing, step climbing, elliptical training) is a better investment than strength training. Here's why, with all figures taken from the authoritative "Compendium of Physical Activities." Let's say you have time to exercise for 40 minutes a day. You weigh 150 pounds, and you can do either 40 minutes of modest running (8:30 pace) or 40 minutes of moderate strength training. The tally:
Physical-activity energy expenditure (PAEE): The running will burn 522 calories, the strength training 136, largely because strength training involves too much sitting and resting between lifts. Advantage: Running, by 386 calories.
Excess post oxygen consumption: EPOC was once thought to give your metabolism a decent boost, but the experts have grown more conservative in their estimates. Most now believe that EPOC burns an extra 20 to 30 calories, about the same between aerobic and strength-building exercise, with both dependent on the length and intensity of your workout. Advantage: Running still leads by 386 calories.
Basal metabolic rate: As noted earlier, BMR isn't easy to change, and increased muscle seems to boost it by just four to six calories per pound. Also, it isn't easy to create muscle, a dirty little secret that's rarely discussed. Eating spinach and lifting weights don't guarantee you biceps like Popeye. Women in particular won't find it easy to build muscle, due to their low testosterone levels. Still, I'm in a charitable mood, so I'll give strength training 30 extra calories a day, because you might be diligent enough to add several pounds of muscle, and that muscle will burn a few extra calories every time you chase the kids, the bus, or a basketball. Advantage: Running's lead has slipped to 356 calories per workout.
And there it stands: If you want to boost your metabolism to lose more weight, run (or walk) around the block as much as you can.
But first, eat less. The experts from the American Dietetic Association and the American College of Sports Medicine all agree, generally advising a 500- to 1000-calorie-a-day reduction. Without this--that is, with exercise alone--few people succeed in their weight-loss efforts. Weight loss works best when you: (1) Eat less; (2) Add exercise to increase your daily calorie deficit; (3) Keep exercising to keep the pounds off.
The more you exercise, the better. The National Weight Control Registry has followed more than 5,000 people who have lost at least 30 pounds and kept it off for more than six years. Their secret? They burn almost 400 calories a day in exercise, mostly by walking. This takes an hour or more a day, but by running you can cut that time almost in half.
When you're done, spend a few minutes on strength-training exercises. Strength training really is good. It adds variety to your workouts, rarely causes injuries, and can build extra muscle to go with the enhanced aerobic fitness that comes from continuous exercise.
And then there's the part about looking sleeker and sexier, and who can argue with that?