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Q: I read that slow walking burns more calories than
walking the same distance at a faster pace. Is this true?
A: That was the finding stated in a News Release
issued by the University of Colorado at Boulder News Center. It was also reported in Tufts
University Health & Nutrition Letter (October 2005) and elsewhere. Ray
Browning, a doctoral student at CU-Boulder’s Integrative Physiology Department
and lead author of the study referenced in the News Release, said people who walk a mile at the leisurely
pace of two miles per hour burn more calories than if they walk the same
distance at three miles per hour. Browning also said the slower pace reduced the
load on the subject’s knees by up to 25 percent. “The message is that by
walking more slowly, obese individuals can burn more calories per mile and may
reduce the risk of arthritis or joint injury,” he said. Because slow walking
doesn’t significantly improve cardiovascular fitness, he recommended also
doing more “vigorous low-impact activities.”
The News Release says a paper on the study was published in
the journal Obesity Research. We were unable to find a report on
the study, however. We looked for the Obesity Research journal
online and at the University of New Mexico Health Sciences Library &
Informatics Center without success. We wanted more details, such as the number
of additional calories burned at the slower pace. Frankly, we are dubious about
the finding. Nevertheless, we believe that Browning’s recommendations have
merit. First, the doubts.
As explained in the nearby FAQ, Walk or Run?, it is
a simple matter of physics: moving a specific mass a specific distance
requires a given amount of energy. As long as you don’t significantly change
gait or break into a run, it makes no difference whether you walk 2- or
3-miles-per-hour. Cover a mile and you burn the same number of calories. Weight
makes a difference, of course; a 250-pound person burns more calories walking a
mile than a person weighing 150.
Princeton Longevity Center Medical News: “The amount of energy is exactly
the same whether that distance is covered in a second, a minute or a year. Walking
slower means taking more time to cover the same distance. Therefore, it
takes you longer to burn those calories when you walk slower.”
Fein added pointedly: “So, it
is much more likely that an unidentified error accounts for the findings of the
[CU-Boulder] study.”
Combining slow walking and more vigorous low-impact
activities, as Ray Browning and his colleagues recommend, makes a lot of sense,
however. That was my suggestion in Challenge Yourself. I do a
combination of high-intensity intervals and low-intensity walking—and very
little of the moderate-intensity aerobics that most people do. I call this my barbell
aerobics strategy because, like a barbell, it uses both ends of the
intensity spectrum—with almost nothing in between.
The rationale is pretty straightforward. Walking at a
comfortable pace burns calories without interfering with recovery from weight
training and high-intensity aerobics. In fact, I believe it speeds recovery by
improving circulation; it brings building materials to the muscles and carries
away fatigue products. What’s more, there is good evidence that leisurely
walking burns peripheral fat--love handles, for example--without interfering
with energy stores in the muscles.
On the other hand, high-intensity intervals build fitness and burn calories--and fat--more effectively than training in the so-called fat burn zone. For more details, see Challenge Yourself.
* * * *
Thanks to Dave Herzel, UNM Libraries Circulation and Reserves Coordinator (and frequent visitor), we now have a copy of the Browning study as reported in Obesity Research. The study is more involved than the news reports suggest. Focusing on slow walking burns more calories diverts readers from the main point.
Browning and his colleague Rodger Kram did find that obese adults burn more calories walking 2520 meters slow than walking the same distance at a normal pace, but it took 40% longer (42 minutes compared to 30 minutes) and the calorie-burn difference was negligible (182 versus 177).
The key point isn't that slow walking burns more calories, but that obese people are generally less fit and, relatively speaking, have to work harder walking at a given pace than someone of normal weight. Plus, brisk walking is more stressful on the joints of obese people.
Browning and Kram had obese and normal weight people walk for 5 minutes at six different speeds. Surprisingly, they found that the preferred walking speed for obese adults is not slower than the pace favored by normal weight people. "It is not known whether obese adults would maintain the same walking speed during a longer trial, [for example] 30 minutes," they wrote. "Given the limited functional aerobic capacities of obese adults, they may prefer to walk slower if duration or distance of the trial is extended."
The researchers main objective was not to find the walking speed that burns the most calories, but to find a pace that would encourage obese individuals to walk more. In summary, they wrote: "Our results suggest that walking slower for a set distance [as opposed to a set time] may be an appropriate exercise recommendation for a weight management prescription in obese adults."
Feedback from a formerly obese reader after reading our original FAQ confirms and amplifies the Browning report conclusion. Walking was his salvation. "At 300+ lbs, running stinks!" he wrote. "I looked terrible in spandex, everything wobbled and wiggled as I jogged, it hurt, and I could not go very far at all. Perhaps 100 ft before being winded and disappointed." Fast walking, I assume, would've posed a similar problem. Rejoicing, he reported: "Ultimately it was walking that played a big part in losing close to 100 lbs and getting back to a healthier weight."
The bottom line is that the best pace is one you can do--and enjoy.
Q: You recommend weighing once a week. Why?
A: I’ve been weighing myself regularly, daily in
the early years and more recently weekly, for over 30 years. That’s one of the
reasons why I’ve never found it necessary to count calories. I follow a
consistent eating pattern and let the scales do the counting for me.
Weighing once a week--always on the same day and under the
same circumstances--tells me whether I’m gaining, losing or maintaining. It
lets me know when to make small adjustments in my eating or activity level. With
the help of this regular feedback, my weight has rarely fluctuated more than a
few pounds either way.
It works for me—and now there’s a study showing that
monitoring weight will work for others as well. Lead researcher Rena R. Wing, a
psychologist and director of the Weight Control and Diabetes Research Center at
Brown University Medical School in Providence, RI, presented the details at an
obesity conference in Vancouver, British Columbia, Canada, on October 16, 2005.
Wing’s presentation was covered by The Associated Press
and widely reported.
The study focused on the main challenge that all successful
dieters face—keeping the weight off. It involved 291 people, mostly women,
average weight 171, who had lost an average of 44 pounds over the last two
years. The subjects were divided into three groups with different levels of
communication: face-to-face, Internet and newsletter. The first two
groups had more direct contact than the third group. They
were counseled weekly for four weeks--with special attention given to those who
had gained 5 pounds or more--and then monthly for 17 weeks. The third group was
counseled by means of a monthly newsletter. All participants were given scales
and encouraged to use them every day.
All three groups were relatively successful at maintaining
their weight. At the end of the study, 18 months later, the face-to-face group
had gained only 2.5 pounds on average, the Internet group gained 6 pounds and those
receiving the newsletter gained 10.4 pounds. Obviously, the intensity of support
and contact made a difference. That was expected. The surprise was the inverse correlation between weight gain and weight monitoring.
Those receiving the most attention weighed themselves more
often—and were more successful at maintaining their weight loss. At the start
of the study only 40% were weighing themselves daily. A year and a half later, that figure
had fallen to 30% in the newsletter group, but increased to 65% in the online
group and 72% in the face-to-face group.
Most notably, only 39% of the daily weighers gained five
pounds or more, while 68% of those who weighed themselves less often gained five
pounds or more.
“You’re more likely to catch changes in body weight” if you weigh every day, Wing explained. “It’s much easier to get back on track if you’ve just gained a pound or two.”
That’s correct, but weighing weekly is more convenient and,
I maintain, more helpful in the long run.
It’s true that you can learn a lot about how your body
works by weighing every day. For instance, you’ll discover that you can’t
get fat in one day; lasting changes of a pound or two, up or down, do not
occur in a day, or two or three. You’ll learn that body weight naturally
fluctuates from day to day, with no real change in body composition. That’s why daily weighing can
actually be counterproductive. The normal ups and downs
can be very unsettling for a weight conscious person, without indicating much at
all about real changes in body composition.
On the other hand, weighing once a week, on the same day
and under the same circumstances, tells you what’s really happening. After a
few weeks of record keeping, a trend will be apparent. You’ll know
whether you’re gaining, losing or stable.
My advice is to weigh every day until you get a handle on normal day-to-day fluctuations. After a short time, you’ll realize that weekly weight is much more meaningful. It indicates what’s really happening, and tells you whether action is necessary.
With practice, and a record of success, you’ll find that maintaining an ideal weight becomes easier as time goes on.
That was one of the findings in a new
update of the National Weight Control Registry: a database of 4,000
people who have lost an average of 33 kg (73 lbs) and kept it off for more than
five years. (See article 14, Fat Loss & Weight Control category, for more
about the NWCR.) Rena R. Wing and Suzanne Phelan (an assistant professor of
psychiatry and human behavior, also at Brown University Medical School), co-authors of an article on
long-term weight loss maintenance for the Registry update, wrote: “After
individuals have successfully maintained their weight loss for 2-5 years, the
chance of long-term success greatly increases.” (American Journal of
Clinical Nutrition, July 2005)
People who maintain their new weight for two years “have
a greater likelihood of keeping if off for two more years,” Phelan told Washington
Post staff writer Sally Squires. “Those who maintain it for five years
have even greater odds of maintaining their weight loss. With time, the odds of
regaining weight go down and down and down.”
Most Registry members, of course, step on the scales regularly.
Q: How much exercise will it take to burn off the fat on
my belly?
A: Until very recently I would’ve told you simply
that you must reduce the fat all over your body to reduce the fat on your
waistline, and that the amount of exercise required depends on the individual.
That’s still true, but a new study by exercise physiologist Cris Slentz, PhD,
and his colleagues at Duke University, reported in the Journal of Applied
Physiology (99-4: 1613-1618, 2005), provides fascinating dose-response
details. “In this study,” Slentz et al write, “we present data from the
first prospective…study on the effects of different amounts of exercise on
visceral, subcutaneous, and total abdominal fat.”
The researchers randomly assigned 175 sedentary, overweight
men and women, age 40-65, to four groups: 1) no exercise; 2) low amount,
moderate intensity exercise (equivalent to walking 12 miles/week at 40-55% of
peak oxygen consumption); 3) low amount, vigorous intensity (jogging 12
miles/week at 65-80%); and 4) high amount, vigorous intensity (jogging 20
miles/week, 65-80%). Total exercise time was approximately three hours a week for
groups 2 and 4, and two hours for group 3. There was no high amount, low
intensity group, because the time required (up to 8 hours a week) “would
seriously limit recruiting ability;” it would be too time-consuming to be
practical for most people.
The study period was 6 months for the no-exercise control
group, and 8 months for the three exercise groups, 2 months ramp-up and 6 months
of steady-state training. The subjects were instructed not to change their diet;
calorie intake, measured before and after the 6-month training period, did not change
significantly. Finally, computed tomography scans, before and after the six
months, were used to measure changes in abdominal fat.
The three key results are sometimes
surprising.
The change in the first group, the control group, was a shocker. While doing
nothing for six months, no change in diet and no exercise, the control group
gained a substantial amount of visceral fat: 8.6% on average. Interestingly, total bodyweight and subcutaneous fat (fat under the
skin) were essentially unchanged, at plus 1%. Total abdominal fat increased by
3.9%. Apparently, the gain in visceral fat was easy to overlook. You might say it
was a stealth effect.
In addition to being a surprise, the increase in fat deep inside the body around the internal organs constitutes a
significant health risk. Increased levels of visceral fat, the researchers
explain, are associated with diabetes, cardiovascular disease and other
metabolic disorders. That’s probably because deep fat is readily absorbed into
the bloodstream.
“The results of our investigation show that in sedentary
overweight adults who continue to choose a sedentary lifestyle the detrimental
effects are more rapid than we previously thought,” Dr. Slentz said in a news
release issued by the Duke University Medical Center. Perhaps worse, hard to
detect fat accumulation may give a false sense of security.
That’s the bad news.
“The second key finding was that in both low-amount
groups, no significant increase in visceral fat was observed,” the researchers
wrote, “suggesting that this amount of exercise was adequate for preventing
the deterioration seen in the inactive controls.” Three hours a week of
moderate intensity exercise or two hours of vigorous intensity, roughly the
amount recommended by the Centers for Disease Control and the American College
of Sports Medicine, essentially stopped fat accumulation. Bodyweight, along with
visceral, subcutaneous and total abdominal fat did not change significantly in
either of the low amount exercise groups.
The researchers were justifiably encouraged. “In view of
the high rate of recidivism with weight-loss programs, the importance of
prevention cannot be overemphasized,” they wrote.
Interestingly, exercise intensity did not appear to have
any effect on bodyweight or any of the abdominal fat categories. Both low-amount
groups, walking and jogging, experienced similar results. This is consistent
with conventional wisdom that walking and running a given distance burns the
same amount of calories. It’s inconsistent, however, with the nearby FAQ
explaining that running actually burns twice as many net calories as walking.
What gives? The researchers don’t offer an explanation, but I have some ideas
why the equivalent of walking and jogging 12 miles a week produced the same response.
First, the actual exercise was done on treadmills,
elliptical trainers and cycle ergometers. The amount of exercise was expressed
in terms of walking or jogging to “simplify the description of the exercise
groups.” The explanation given by Amby Burfoot in the FAQ that the center of
gravity moves up and down in running but not in walking would not apply to an
elliptical trainer or stationary bike. What’s more, steady state jogging at
65-80% of VO2max is not high-intensity compared to traditional intervals, and
certainly not the equivalent of the Tabata protocol. (See article 152, Sprints
Build Endurance!, Aerobic
Exercise category.)
“Importantly, a modest increase over the CDC/ACSM
exercise recommendations resulted in significant decreases in visceral,
subcutaneous, and total abdominal fat without changes in calorie intake,”
Slentz et al wrote. The equivalent of jogging 20 miles a week at 65-80% resulted
in about 7% reduction in each of the fat compartments, visceral, subcutaneous and total
abdominal fat. The reduction in body weight was only 2.6%, however, confirming that the
scale doesn’t tell the whole story.
Again, the researchers had reason to be encouraged: “Taken
together, the data suggest a clear dose-response relationship between exercise
amount and changes in visceral fat,” they wrote. “With greater amounts of
exercise, greater biological benefits accrue.” In the news release, Slentz
added: “While this may seem like a lot of exercise our previously sedentary
and overweight subjects were quite capable of doing this amount.”
Bottom line: Be optimistic. This study clearly shows that a reasonable amount of exercise will stabilize or burn off your belly fat—and improve your health. Substitute intervals, add weight training and eat slightly less, and you’ll be able to see your abs before you know it.
Q: How many calories are burned walking or running a
mile?
A: Ask Sir Isaac Newton. It’s a simple matter of
physics: moving a specific mass a specific distance requires a given
amount of energy. Every weight loss buff knows that it makes no difference
whether you walk or run, cover a mile and you burn about 100 calories. Trouble
is, as is often the case with conventional wisdom, it isn’t true. Generally
speaking, running burns twice as many net calories per mile as walking.
Researchers at Syracuse University in New York actually
measured the energy expended walking and running and reported their findings in
the December 2004 Medicine & Science in Sports & Exercise,
the official journal of the American College of Sports Medicine. Turns out to be
more complicated that I -- and many others -- thought.
Jill A. Kanaley, PhD, and her colleagues in the Department
of Exercise Science recruited 24 recreationally active subjects from the
Syracuse campus and surrounding community, 12 females and 12 males, age 18 to
30, and measured the oxygen consumed while running and walking a metric mile
(1600 meters) on a treadmill and a track. Using the principle that five calories
are burned for every liter of oxygen consumed, the researchers found that the
men burned an average of 124 calories while running and 88 while walking, while
the women burned 105 and 74. (The men burned more calories because they weigh
more and have more fat-free mass). In short, both the men and women burned about
41% more total calories running than walking.
However, when the energy consumed at rest was subtracted,
the men burned 105 calories running and only 52 walking, and the women burned 91
and 43. Net calorie burn (total calories minus calories burned at rest) is the
critical number, of course. Tempting as it may be, you can’t count the
calories you would’ve burned in any event, for example, sitting on the couch
watching TV. As you can see, the net calories burned running is double that for
walking.
The study doesn’t explain why Newtonian physics failed so
badly in this case, but longtime Runner’s World editor Amby
Burfoot figured it out with the help of David Swain, PhD, director of the
Wellness Institute and Research Center at Old Dominion University. Swain says,
“Running in general consumes more oxygen than walking.” Here’s why.
The physics principle would be right if walking and running
was an apples-to-apples proposition. But it’s not. Walking and running is more
like apples and oranges. Walking takes you from point A to point B in a straight
line like a bowling ball, while running is more like a bouncing ball. “When
you walk, you keep your legs mostly straight, and your center of gravity rides
along fairly smoothly on top of your legs,” Burfoot writes. “In running, we
actually jump from one foot to the other. Each jump raises our center of gravity
when we take off, and lowers it when we land, since we bend the knee to absorb
the shock. This continual rise and fall of our weight requires a tremendous
amount of Newtonian force (fighting gravity) on both takeoff and landing.”
That doesn’t mean, of course, that walking is a bad
weight-control strategy. Walking is something almost everyone can do. It’s
still a terrific way to keep calories consumed and calories burned in balance.
As Swain reminded Burfoot: “The new research doesn’t mean that
walking burns fewer calories than it used to. It just means that walkers might
have to walk a little more, or eat a little less, to hit their weight goal.”
I believed in walking before, and I’m still a believer. Walking is an enjoyable and convenient way to burn fat and speed recovery from high intensity workouts; for more details, see A Barbell Aerobics Strategy in Challenge Yourself.
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