Can Weight Training Really Boost Metabolism?

Thursday Jun 25, 2015 | BY |
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Boost Your Metabolism card with colorful background with defocused lights

Is it really true that we can “boost” our metabolism?

One really frustrating thing about getting older is that the eating habits that have served us well for years suddenly start eroding our health.

We’re not doing anything different, but we’re putting on the pounds, or feeling more tired, or finding our thinking isn’t quite as sharp as it used to be.

Many of us blame it on our metabolism. It’s slowing down, we say. Age, hormonal changes, and activity changes all work together to make it harder to burn calories.

Still, we’re told, we can get that metabolism revved up again. All we have to do is commit to exercise and strength training.

But how much do these activities really raise basic metabolic rate?

Turns out it’s not as much as we thought.

What Happens to Metabolism?

There is a lot of confusion about metabolic rate. We can think of it as the number of calories needed to keep the body going when it’s at rest—the calories required to run basic processes like breathing, pumping blood, and managing waste. (It’s not about how fast we burn calories, but about how many we need for the body to survive.)

This is called your basic metabolic rate (BMR), and it accounts for about 75–80 percent of the calories you use each day. The rest go to helping you digest food and to supporting physical activity. Anything that’s not used in these three processes is stored as fat.

The Mayo Clinic puts it simply: metabolism is influenced by three things:

  1. Body size and composition
  2. Sex (men typically have less fat and more muscle, burning more calories)
  3. Age

Here’s a closer look at what can affect our BMR, or reduce our daily caloric burn:

  • Age and metabolism: After the age of 25, which is when we stop growing bone, our metabolic rate goes down, but only slightly—by about two percent per decade. That means that a woman consuming 1,800 calories a day up to age 25 would have to cut back to 1,728 per day in her next decade, and 1,658 in the decade after that. That may not seem like much, but you’ll notice if you try to cut that amount of calories every day that it’s likely to be difficult. A 2010 study also noted that resting metabolic rate changes with age even in situations where body composition doesn’t change: “There is indirect evidence suggesting that the metabolic rate of individual organs is lower in older compared with younger individuals,” researchers wrote.
  • As muscles go, metabolism goes: We tend to lose muscle as we age and gain fat, and muscles, in general, burn more calories than fat. This muscle loss also seems to be associated with some decline in metabolism. A 1988 study, for instance, concluded that age-related loss of muscle mass in both men and women was associated with a slight decline in metabolism rate.
  • Metabolism increases/decreases with size: Overweight people typically have a faster metabolic rate than slim people, simply because it takes more energy to support and manage the larger body. When you lose weight, your metabolism may actually drop just a little, because your body now needs less energy than it did before. That can really mess up your mind when it comes to figuring out how much food you need to eat to support a smaller body—even if it is more active than the larger one was.
  • The body is efficient: We may sometimes wish it wasn’t, but the body is an efficient machine, and is constantly adapting. It gets used to physical exercise, and over time, gets to where it can do the same exercise with fewer calories. This doesn’t necessarily affect your BMR, but it can affect the amount of calories you burn each day—and the amount that’s converted into fat.
  • Medical conditions: Hypothyroidism, diabetes, Prader-Willi Syndrome, and other medical conditions can slow down metabolism.

All these things and more can work together to create a body system that simply doesn’t need as many calories as we’re giving it. Meanwhile, we can continue to overload ourselves out of habit.

The Truth about Weight Training and Metabolism

As we find ourselves aging and our systems slowing down somewhat, we may feel frustrated that we’re essentially eating the same amounts of food, but we’re gaining weight.

The solution?

Boost the metabolism!

Advice abounds on the Internet for how to accomplish this. The most common suggestion, by far, is to commit to a program intended to increase muscle mass.

Whether you call it weight training, resistance training (RT), or strength training (ST), it’s today’s panacea for a sluggish metabolism. Get more muscle in the body, the thinking goes, and you’ll require more calories for basic functioning. Even if you’re just sitting around, if you have more muscle, your body will burn more calories.

There’s no doubt that muscle burns more calories than fat. But does additional muscle actually increase the amount of calories the body needs to perform basic functions?

Turns out that this isn’t as clear-cut as we may have been led to believe. Researchers from the University of New Mexico, for instance, note: “speculation exists as to whether resistance exercise can truly accelerate a slowing metabolism or provide substantial success to a weight loss intervention.”

They go on to state that though muscle is the largest tissue in the body, “it’s estimated metabolic rate is much less than has been advertised in the consumer media and suggested by many ill-informed fitness product advertisers.”

Research shows that muscle has a metabolic rate of about 4.5 to 7.0 kcal/lb per day, with muscle contributing about 20 percent of total daily energy expenditure (TDEE) vs. 5 percent for fat tissue—but keep in mind that 80 percent of TDEE goes to running the heart, lungs, kidneys, brain, liver, and more.

“These organs have a metabolic rate that is 15-40 times greater than their equivalent weight of muscle and 50-100 times greater than fat tissue,” researchers state.

Still, it seems that gaining more muscle would help. According to a 2003 study, it does—but a lot less than you may think. Scientists conducted a large review of the literature, and found that most peer-reviewed resistance training studies showed increases of only 2.2 to 4.5 pounds of muscle mass. That would translate to an increase in resting metabolic rate of only about 50 calories a day (for 4.5 pounds of muscle).

That’s about 12 cherries, or ½-cup sugar snap peas.

Other studies have shown similar results, with high-intensity strength training boosting metabolism the next day. In 1994, for instance, scientists reported that male subjects 22-35 years who engaged in a strenuous bout of resistance exercise had “significantly” elevated RMR’s 14.5 hours after they’d finished.

A 1993 study showed similar results—men who completed a 90-minute, high-intensity weight lifting session had about a 9 percent increased RMR 15 hours later. (High-intensity may be the key, here.)

A smaller study in 1994 supported the same idea. Participants went through a 12-week program of resistance training and gained, on average, about 3.1 pounds of lean muscle weight. Their RMR increased by about 6.8 percent.

Women Benefit Much Less Than Men

Other studies have shown that while men may boost their metabolism with weight training (even if it’s only by 7–9 percent), women may see few metabolic benefits.

Take a 2001 study, for instance. Researchers followed about 40 participants. After 24 weeks of strength training, when all results were pooled together, resting metabolism increased by only about 7 percent. The results were the same for both young (20-30 yr) and older (65-75 yr) adults.

When the results were split up between the genders, though, they were quite different. Men increased resting metabolism by about 9 percent, whereas women showed no significant increase. When resting metabolic rate (RMR) was adjusted for fat-free mass, men still showed a significant elevation, but women did not.

“In conclusion,” the researchers wrote, “changes in absolute and relative RMR in response to ST are influenced by gender but not age.”

It Really Is About How Much We Eat

In 2012, researchers published a very interesting study. They compared daily energy expenditure between Hazda hunter-gatherers (an ancient culture still in existence today) with that of modern Westerners.

Surely the hunter-gatherers would use up more energy each day and have higher metabolic rates!

But results showed the opposite—though physical activity level was greater among the foragers, average daily energy expenditure (calories burned) was no different between the groups after controlling for body size. The metabolic cost of walking, for instance, and resting, were similar.

“The similarity in metabolic rates across a broad range of cultures challenges current models of obesity suggesting that Western lifestyles lead to decreased energy expenditure,” scientists wrote. They concluded that differences in obesity prevalence—the hunter-gatherers had less body fat and mass—came from differences in energy intake (how much we eat) rather than in energy expenditure (how much we burn).

What About the “After-Burn?”

There is also the idea that even if exercise and weight training don’t boost your metabolism much on the whole, they will help you burn calories for hours afterward—the so-called “afterburn” effect.

According to a 2009 study, this has probably been overhyped as well.

Scientists published their findings in the journal Exercise and Sport Sciences Review. They studied active people who, on separate days, performed either low- or high-intensity cycling, or no exercise at all. They compared endurance athletes as well, and sedentary obese people with sedentary lean people, and older men with younger men.

Not once did they find that people burned more fat in the 24 hours after exercise than they did when they didn’t exercise.

“Bottom line is that we once thought that exercise would burn calories, especially fat calories, for a long period after a bout of exercise,” said exercise physiologist Gerald Endress, fitness director for the Duke University Diet and Fitness Center. “This does not seem to be the case.”

He added that the idea exercise significantly boosts resting metabolism is also not supported by evidence. “Average fitness enthusiasts will only add four to five pounds of lean mass,” he said, and burn an additional 28 to 50 calories a day.

Looking to the Future

There are many health benefits to both regular exercise and resistance training. Exercise reduces risk of just about every disease known to man, and strength training improves muscle strength and tone, protects joints from injury, improves balance, increases bone density and strength, and increases stamina.

Expecting either to significantly boost metabolism, though, may be a mistake. There are books out there saying that if you replace 10 pounds of fat with 10 pounds of muscle, you’ll maintain a similar weight but burn 500 additional calories a day—while at rest.

We just have no evidence showing this to be the case.

What do you think about exercise/weight training and metabolism? Please share your thoughts.

* * *

Sources
Gabriella Boston, “Basal metabolic rate changes as you age,” Washington Post, March 5, 2013, http://www.washingtonpost.com/lifestyle/wellness/basal-metabolic-rate-changes-as-you-age/2013/03/05/d26b1c18-80f1-11e2-a350-49866afab584_story.html.

Johannsen DL, et al, “Metabolic slowing with massive weight loss despite preservation of fat-free mass,” J Clin Endocrinol Metab., July 2012; 97(7):2489-96, http://www.ncbi.nlm.nih.gov/pubmed/22535969.

Shari Roan, “Metabolism, Weight-Gain Link Refuted: Research: Dieters’ ability to burn off calories bounces back, a study finds. But weight loss is still difficult to maintain for reasons that are poorly understood,” LA Times, August 8, 1990, http://articles.latimes.com/1990-08-08/news/mn-165_1_metabolic-rate.

Mayo Clinic Staff, “Metabolism and Weight Loss: How you burn calories,” Mayo Clinic, September 19, 2014, http://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/metabolism/art-20046508.

“Sarcopenia: Muscle Loss from Aging,” Berkeley Wellness, December 4, 2013, http://www.berkeleywellness.com/fitness/injury-prevention/article/sarcopenia-muscle-loss-aging.

J.L. Fleg, E.G. Lakatta, “Role of muscle loss in the age-associated reduction in VO2 max,” Journal of Applied Physiology, September 1, 1988; 65(3):1147-1151, http://jap.physiology.org/content/65/3/1147.

Susan Bowerman, “Can your metabolic rate make you gain or lose weight?” Discover Good Nutrition, September 23, 2013, http://www.discovergoodnutrition.com/2013/09/metabolic-rate/.

Marie-Pierre St-Onge, and Dympna Gallagher, “Body composition changes with aging: The cause or the result of alterations in metabolic rate and macronutrient oxidation?” Nutrition, February 2010; 26(2):152-155, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2880224/.

Paige Kinucan and Len Kravitz, “Controversies in Metabolism,” University of New Mexico Exercise Science, http://www.unm.edu/~lkravitz/Article%20folder/metabolismcontroversy.html.

Donnelly, J.E., Jakicic, J.M., Pronk, N., Smith, B.K., Kirk, E.P., Jacobsen, D.J., Washburn, R. “Is Resistance Training Effective for Weight Management?” Evidence-Based Preventive Medicine. 2003; 1(1): 21-29.

Lemmer JT, et al., “Effect of strength training on resting metabolic rate and physical activity: age and gender comparisons,” Med Sci Sports Exerc., April 2001; 33(4):532-41, http://www.ncbi.nlm.nih.gov/pubmed/11283427.

Jacqueline Stenson, “Exercise not likely to rev up your metabolism,” NBC News, May 26, 2009, http://www.nbcnews.com/id/30826120/ns/health-fitness/t/exercise-not-likely-rev-your-metabolism/#.VWS1rWRVhBc.

C A Gillette, et al., “Postexercise energy expenditure in response to acute aerobic or resistive exercise,” International Journal of Sport Nutrition, 1994; 4(4);347-360, https://www.mendeley.com/catalog/postexercise-energy-expenditure-response-acute-aerobic-resistive-exercise/.

C Melby, et al., “Effect of acute resistance exercise on postexercise energy expenditure and resting metabolic rate,” J Appl Physiol, 1993: 75: 1847-1853, https://www.mendeley.com/research/effect-acute-resistance-exercise-postexercise-energy-expenditure-resting-metabolic-rate/.

Campbell WW, et al., “Increased energy requirements and changes in body composition with resistance training in older adults,” Am J Clin Nutr., August 1994; 60(2):167-75, http://www.ncbi.nlm.nih.gov/pubmed/8030593.

Colleen M. Story

Colleen M. Story

Colleen M. Story, a northwest-based writer, editor, and ghostwriter, has been creating non-fiction materials for individuals, corporations, and commercial magazines for over 17 years. She specializes in the health and wellness field, where she writes and ghostwrites books, e-books, blogs, magazine articles, and more.

Colleen is the founder of Writing and Wellness. Her fantasy novel, “Rise of the Sidenah,” was released with Jupiter Gardens Press in September 2015. Her literary novel, “Loreena’s Gift,” is forthcoming in spring 2016 from Dzanc Books. She lives in Idaho. www.colleenmstory.com

3 COMMENTS ON THIS POST

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  1. Carole says:

    Wow, what a downer article. So you’re saying that your metabolism is definitely going to slow down, you’re going to get fat if you don’t decrease your food intake, and exercise doesn’t matter. I disagree.

    Most of us consider metabolism how fast our body burns the food we eat. OK, not scientific, but so be it.

    As we age, we are doing things differently. We’re not chasing kids around, living with sports and school schedules, worrying about kid’s nutrition. Many stop worrying about healthy dinners altogether. There’s less to clean, less laundry and shopping… Now you can come home, pop your microwave dinner in and watch the standard 3 hours of TV.

    We all know that eating healthy, getting enough sleep, and exercising are the way to keep fit and full of energy. The more active you are, the better quality of life you will have for longer.

    I’m 59. I wear a size 3. I have a very active lifestyle. I’ve been nagging (I mean coaching…) my sister for years. She recently told me that she thinks she is losing too much weight.

    Maybe our way of looking at things is not scientifically perfect, but it works and we’re sticking to it. Don’t be disheartened by articles like this.

  2. Chris Califano says:

    Actually, the average person can significantly boost their fat burning metabolism, but not with average resistance, weight or strength training as people call it. The studies that are cited, and many more like them, are done for limited lengths of time, and thus with subjects with limited experience. Unless you have experience with metabolism- boosting weight training (not the way most people do it at all) then you will be misled and even discouraged by seeing these study “results”. Unless you read and study the entire “study” then you will not know how they did it. Time, duration, and intensity are very loose terms. Since I am a certified physical specialist for 35 years training clients, I know what works in the real world, and I have yet to find one single study yet that has even similar results, unless it is lesser known (but I do have them and I reserve them for my own clients and intsructional program).

    What matters is that 99% of food or fitness studies are not real world, as most of you know from nutrition, especially vegan and GOSH! raw vegan studies… Seemingly miraculous results, for example never suffering cold or flu for a dozen years in a row… are common with the PROPER raw vegan diet… but not the way the typical health food store customer does it…

    Food and fitness studies are the hardest to do… since most people either lie on the surveys, plus the methods used are varied. What one person calls “exercise” is not at all what another one actually does…. and so on….

    So again the best knowledge is not easy— or fast— or from a study.. It must come from experience, especially nutrition and fitness.. which are HUGE “abstract” areas for most people.

  3. William says:

    If body temperature is an accurate indicator of RMR, then too much exercise can also decrease RMR. It has happened to me. For years, my body temperature averaged 97F and has even dipped to 95.5F. I felt cold most of the time. It was only after cutting back on exercise that my body temperature went above 97F and sometimes 98F. Other benefits include thicker hair, decreased urination frequency, and skin that is no longer dry. My six-pack is not as defined as before but I’ll gladly trade that for thicker hair.

    Increasing RMR may not be the goal to aim for with advancing age. Why should metabolism remain the same when our body is in maintenance mode and not in a growth phase as a person in their 20s? As our cells approach the Hayflick limit, we should respect our body’s mechanism to promote longevity by slowing down our metabolism (such as decreasing T4 with increasing age: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2682478). With slower metabolism, it follows that we should eat less.

    I do believe that we burn more calories with exercise — but too much will backfire and decrease RMR once the the preservation threshold has been breached.

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