[Paleopsych] NYT: The Fit Tend to Fidget, and Biology May Be Why, a Study Says
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Fri Jan 28 15:58:17 UTC 2005
The Fit Tend to Fidget, and Biology May Be Why, a Study Says
[The Science article itself is appended.]
By DENISE GRADY
Overweight people have a tendency to sit, while lean ones have
trouble holding still and spend two hours more a day on their feet,
pacing around and fidgeting, researchers are reporting in findings
The difference translates into about 350 calories a day, enough to
produce a weight loss of 30 to 40 pounds in one year without trips to
the gym - if only heavy people could act more restless, like thin
The difference in activity levels may be biological and inborn, the
researchers say, the result of genetically determined levels of brain
chemicals that govern a person's tendency to move around. It is the
predisposition to be inactive that leads to obesity, and not the other
way around, they suggest.
The findings, being published today in the journal Science, are from a
study in which researchers at the Mayo Clinic outfitted 10 lean men
and women and 10 slightly obese ones - all of whom described
themselves as "couch potatoes" - with underwear carrying sensors that
measured their body postures and movements every half second for 10
days on several occasions. By the end of the study, which required a
staff of 150, the researchers had collected 25 million pieces of data
on each participant.
One thing that convinced the scientists that the activity levels were
innate, and not the product of a person's being overweight or
underweight, was that the levels did not change when the subjects were
forced to gain or lose weight in different phases of the study. To
make sure they knew exactly how many calories the subjects were
eating, the researchers cooked all their meals for weeks at a time,
and had them pledge not to cheat. A total of 20,000 meals were
The director of the study, Dr. James Levine, an endocrinologist and
nutritionist at the Mayo Clinic, said the findings offered hope to
overweight people, suggesting that relatively simple and painless
changes in their daily behavior, like making an effort to walk more
and ride less, could help control weight. He said increases in obesity
in recent decades could be traced more to declines in daily exercise -
more time spent in cars, behind desks and in front of computers and
televisions - than to increases in eating.
In an environment that allows people to be sedentary, those with a
biological predisposition to sit still will do so, he said. In
contrast, the restless ones will still find ways to burn off calories,
even if it means walking around their desks.
"People with obesity are tremendously efficient," Dr. Levine said.
"Any opportunity not to waste energy, they take. If you think about it
that way, it all makes sense. As soon as they have an opportunity to
sit down and not waste those calories, they do."
Participants in the study went through three 11-week phases over a
year or so in which their diets were controlled to maintain, increase
or decrease their weight. They were paid $2,000 at the end of each
phase, for a total of $6,000.
Each phase included a 10-day period during which they had to wear the
underwear with the sensors around the clock, taking it off for only
about 15 minutes a day to shower and get a fresh set from the
The top was either an undershirt or a sports bra made of Lycra, and
the bottom was a risqué-looking pair of shorts with openings at the
crotch and backside so the garment would not have to be lowered during
the day, which would have disturbed the sensors.
Dr. Levine said he had designed the outfit with a colleague.
"We had to be very creative," he said. "And you have to test them for
comfort. I would put them on top of my suit. Mayo has a very strict
dress code. Nothing gave me more pleasure than to wander around with
this bizarre underwear over my suit."
Dr. Eric Ravussin, an obesity researcher at the Pennington Biomedical
Research Center in Baton Rouge, La., who wrote an essay in Science
about Dr. Levine's study, said that because the tendency to sit still
seemed to be biological, it might not be easy for obese people to
change their ways. "The bad news," Dr. Ravussin said, "is that you
cannot tell people, 'Why don't you sit less and be a little more
fidgety,' because they may do it for a couple of hours but won't
sustain it for days and weeks and months and years."
But Dr. Rudolph Leibel, an obesity researcher at Columbia University
Medical Center, said, "People can be taught and motivated to change
their behavior in service of their health."
Dr. Leibel also noted that although it was plausible that the tendency
to be inactive was biologically determined, it had not been proved.
Dr. Ravussin said it might be possible to help people stay lean by
making their environments less conducive to sitting, though that would
take major societal changes like rebuilding neighborhoods in which
people can walk to markets instead of "the remote shopping mall with
10,000 parking spots and everybody is fighting for the handicapped
A participant in the study, Othelmo da Silva, 41, an academic adviser
at Rochester Community and Technical College in Minnesota, said he was
overweight and felt encouraged by the study and the idea that people
could lose weight by moving around more and did not necessarily have
to join a gym.
As for the idea that the tendency to sit still might be genetic, Mr.
da Silva said no "lazy genes" had been identified and added, "I
personally believe in self-determination over detrimental biological
Dr. Jules Hirsch, an obesity researcher at Rockefeller University,
said studies in the 1950's first suggested that obese people were less
fidgety than thin ones. One study, of young women playing tennis,
showed that although fat and thin ones played equally well, fat ones
wasted less motion hitting the ball. They were seemingly more
efficient, and probably burned fewer calories.
Dr. Hirsch said some people were probably born with, or developed at
an early age, a "greater efficiency at caloric storage," from eating
more or moving less.
"This phenomenon helps store energy," he said, "but is a great risk
factor for the development of obesity."
But until it is understood better, he said, "we're not apt to
understand the overall obesity problem any better."
Dr. Levine of the Mayo Clinic said the study findings had inspired him
to redesign his office. His computer is now mounted over a treadmill,
and he walks 0.7 miles an hour while he works.
"I converted a completely sedentary job to a mobile one," he said.
The walking is addictive and "terribly good fun," Dr. Levine said,
adding that he has had 30 or 40 requests from colleagues at Mayo for
treadmill desks like his.
Has he lost weight? He does not know.
"I'm a relatively lean bloke," he said. "I never weigh myself. You'll
think I'm a bad nutritionist. I don't recommend people weigh
themselves all the time. It's not a healthy thing to do."
Betterhumans > Couch Potatoes Hardwired to Sit
Non-exercise activity a key to staying lean, and some people appear
biologically predisposed against it
1/27/2005 2:20 PM
Non-exercise activity is far more important for leanness than hitting
the gym, suggests a complex study that involved high-tech underwear
monitoring participants 24 hours a day.
The study shows that everything from tapping toes to cleaning the
basement boosts what's been dubbed non-exercise activity
thermogenesis--"NEAT"--and plays a large role in determining who is
lean and who is obese.
"A person can expend calories either by going to the gym, or through
everyday activities," says study leader James Levine of the Mayo
Clinic in Rochester, Minnesota. "Our study shows that the calories
that people burn in their everyday activities--their NEAT--are far,
far more important in obesity than we previously imagined."
In the study, obese people sat on average 150 minutes more each than
lean people, burning 350 fewer calories per day. And importantly for
understanding the origins of obesity, the difference appeared to be
"It most likely reflects a brain chemical difference because our study
shows that even when obese people lose weight they remain seated the
same number of minutes per day," says Levine. "They don't stand or
walk more. And conversely, when lean people artificially gain weight,
they don't sit more. So the NEAT appears to be fixed."
Is that a sensor in your pants?
The findings are based on a complex study involving more than 150
people who helped in planning, design, invention, food preparation and
Ten obese and 10 lean participants were fitted with a special
monitoring system invented by Mayo Clinic researchers.
Incorporating technology used in fighter-jet control panels, the
system uses sensors in data-logging undergarments--bottoms like
bicycle shorts, women's tops like sports bras and men's like
Participants wore the undergarments 24 hours a day, getting a fresh
pair each morning at breakfast when they were also weighed and their
clothing's data downloaded.
Using the system, researchers monitored the body postures and
movements of participants for 10 days. The only things participants
were forbidden to do were swim and eat food the research team didn't
prepare for them.
Next, they overfed lean participants by 1,000 calories per day and
underfed obese participants by 1,000 calories per day.
They then monitored participants' movements every half second for 10
Comparing results, the researchers found that even after losing
weight, the naturally obese group sat more and moved less. And even
after gaining weight, the naturally lean group moved around more.
The researchers conclude that obese people are NEAT-deficient,
possibly because of a cognitive defect in processing biological drives
and environmental cues.
They think that the findings could be used to help reverse obesity
trends, such as by encouraging "NEAT-seeking" behavior.
"This is entirely doable, because the kind of activity we are talking
about does not require special or large spaces, unusual training
regimens or gear," says Levine. "Unlike running a marathon, NEAT is
within the reach of everyone."
Interindividual Variation in Posture Allocation: Possible Role in Human
Science, Vol 307, Issue 5709, 584-586 , 28 January 2005
James A. Levine,* Lorraine M. Lanningham-Foster, Shelly K. McCrady, Alisa
C. Krizan, Leslie R. Olson, Paul H. Kane, Michael D. Jensen, Matthew M.
Obesity occurs when energy intake exceeds energy expenditure.
Humans expend energy through purposeful exercise and through changes in
posture and movement that are associated with the routines of daily life
[called nonexercise activity thermogenesis (NEAT)]. To examine NEAT's role
in obesity, we recruited 10 lean and 10 mildly obese sedentary volunteers
and measured their body postures and movements every half-second for 10
days. Obese individuals were seated, on average, 2 hours longer per day
than lean individuals. Posture allocation did not change when the obese
individuals lost weight or when lean individuals gained weight, suggesting
that it is biologically determined. If obese individuals adopted the
NEAT-enhanced behaviors of their lean counterparts, they might expend an
additional 350 calories (kcal) per day.
Endocrine Research Unit, Mayo Clinic, Rochester, MN 55905, USA.
* To whom correspondence should be addressed. E-mail: Jim at Mayo.edu
Obesity is epidemic in high-income countries. In the United
States alone poor diet and physical inactivity are associated with 400,000
deaths per year (1) and obesity-related medical expenditures in 2003
approximated $75 billion (2). Obesity is also an emerging problem in
middle- and low-income countries, where the health and fiscal costs are
likely to be devastating (3).
As the impact of obesity on health escalates, so too does the
need to understand its pathogenesis. Weight gain and obesity occur when
energy intake exceeds energy expenditure. We are interested in a specific
component of energy expenditure called NEAT and the role it might play in
human obesity. NEAT is distinct from purposeful exercise and includes the
energy expenditure of daily activities such as sitting, standing, walking,
We have previously shown that when humans overeat, activation
of NEAT helps to prevent weight gain (4). To better understand NEAT and
its role in obesity, we separated NEAT into the thermogenesis associated
with posture (standing, sitting, and lying) and that associated with
To investigate whether the obese state has an effect on NEAT,
we first developed and validated a sensitive and reliable technology for
measuring the postural allocation of NEAT in human volunteers (5, 6). This
physical activity monitoring system uses inclinometers and triaxial
accelerometers to capture data on body position and motion 120 times each
minute. By combining these measurements with laboratory measures of energy
expenditure, we can summate NEAT and define its components (7).
To compare body posture and body motion in lean and obese
people, we recruited 20 healthy volunteers who were self-proclaimed "couch
potatoes." Ten participants (five females and five males) were lean [body
mass index (BMI) 23 ± 2 kg/m2] and 10 participants (five females and five
males) were mildly obese (BMI 33 ± 2 kg/m2) (8) (table S1). We
deliberately selected mildly obese subjects who were not incapacitated by
their obesity and who had no joint problems or other medical complications
of obesity. The volunteers agreed to have all of their movements measured
for 10 days and to have their total NEAT measured with the use of a stable
isotope technique (9). They were instructed to continue their usual daily
activities and occupations and not to adopt new exercise practices. Over
the 10-day period, we collected 25 million data points on posture and
movement for each volunteer.
Our analysis revealed that obese participants were seated for
164 min longer per day than were lean participants (Fig. 1A).
Correspondingly, lean participants were upright for 152 min longer per day
than obese participants. Sleep times (lying) were almost identical between
the groups. Total body movement, 89% of which was ambulation, was
negatively correlated with fat mass (Fig. 1, B and C). Notably, if the
obese subjects had the same posture allocation as the lean subjects, they
would have expended an additional 352 ± 65 (±SD) (range, 269 to 477)
calories (kcal) per day (Fig. 1C).
Fig. 1. (A) Time allocation for different postures for
10 obese and 10 lean sedentary subjects. Data are shown as mean + SEM.
Significant differences between lean and obese are indicated: *, P =
0.001; **, P = 0.0005. There were no statistically significant differences
between females (n = 10) and males (n = 10): Females stood 470 ± 35
min/day and males stood 429 ± 40 min/day. (B ) Relationship between total
body movement and body fat content. Body fat, determined from dual x-ray
absorptiometry, is expressed as a percentage (left) and mass (right)
plotted against the total 10-day accelerometer output [accelerometer units
(AU)] for 20 (10 obese and 10 lean) sedentary subjects. The open diamonds
are data for females and the filled diamonds are data for males. There was
no significant relationship between fat-free mass and accelerometer output
(fig. S1). The relationship between NEAT by doubly labeled water adjusted
by weight versus accelerometer output is shown in fig. S2. (C) (Left)
Total daily energy expenditure and (right) NEAT in 10 obese and 10 lean
sedentary subjects. The uppermost segments of the bars for obese
individuals (vertical arrows) represent the additional energy that could
be expended if these subjects were ambulatory for the same amount of time
as lean subjects. BMR, basal metabolic rate; TEF, thermic effect of food.
There was no significant difference in sleeping time between the lean
group (423 ± 15 min) and the obese group (434 ± 17 min). The energy
expenditure data and standard deviations appear in table S2. The
relationship between NEAT measured with doubly labeled water and NEAT
measured with the instruments is shown in fig. S3. [View Larger Version of
this Image (19K GIF file)]
To investigate whether these differences in posture allocation
are a cause or consequence of obesity, we asked seven of the original
obese volunteers (four females and three males, BMI 33 ± 2 kg/m2) to
undergo supervised weight loss over a period of 8 weeks. The average
weight loss was 8 kg. Likewise, we recruited nine of the original lean
volunteers and one additional lean volunteer (six females and four males,
BMI 23 ± 2 kg/m2) to undergo supervised overfeeding over a period of 8
weeks. The average weight gain was 4 kg. After these weight perturbations,
we studied posture allocation in these subjects for another 10 days.
Interestingly, both the obese subjects losing weight and the lean subjects
gaining weight maintained their original posture allocation (Fig. 2).
Thus, it appears that interindividual differences in posture allocation
are biologically determined.
Fig. 2. (A) Posture allocation in seven obese sedentary
subjects who underwent caloric restriction (8 ). (Left) Posture allocation
data at baseline and after weight loss of 8 ± 2 kg. (Right) The time the
subjects spent standing/ambulating at baseline is plotted against the time
the subjects spent standing/ambulating after weight loss. (B) Posture
allocation in 10 lean sedentary subjects who underwent experimental weight
gain (8 ). (Left) The posture allocation data for baseline and after
weight gain of 4 ± 2 kg. (Right) The time the subjects spent
standing/ambulating at baseline is plotted against the time the subjects
spent standing/ambulating after weight gain. Data are shown as mean + SEM.
[View Larger Version of this Image (34K GIF file)]
It should be emphasized that this was a pilot study and that
the results need to be confirmed in larger studies. Nevertheless, the
current data may be important for understanding the biology of obesity and
how best to treat it. The propensity of obese persons to sit more than
lean individuals has several potential explanations. Rodent studies
support the concept that there are central and humoral mediators of NEAT
(10, 11). For example, we have shown that a neuropeptide associated with
arousal, orexin (12), increases NEAT in rats when injected into the
paraventricular nucleus (PVN) of the hypothalamus. Preliminary data
suggest that PVN injections of orexin also cause dose-dependent increases
in standing posture allocation in rats (13). Thus, there may be central
and humoral mediators that drive the sedentary behavior of obese
individuals. The negative relationship between fat mass and movement (Fig.
1B) raises the intriguing possibility that body fat releases a factor that
slows physical activity in obesity. However, these data also demonstrate
that posture allocation is not the mechanism by which NEAT is modulated
with short-term overfeeding. One hypothesis is that this occurs through
modulation of energy efficiency; this is an area worthy of future
These data may also have implications for obesity
intervention. One could argue that obese individuals have a biologically
determined posture allocation and therefore are destined to become obese.
If this were true, obesity would have been as common 50 years ago as it is
today. However, obesity rates have increased and continue to do so (14).
We speculate that obese and lean individuals respond differently to the
environmental cues that promote sedentary behavior. If the obese
volunteers adopted the NEAT-enhanced behavior of their lean counterparts,
they could expend an additional 350 kcal per day. Over a year, this alone
could result in a weight loss of 15 kg, if energy intake remained
unchanged. Herein lies the rationale behind nationwide approaches to
promote NEAT in small increments (15). For example, in Rochester,
Minnesota, in 1920 before car use was commonplace the average walk to and
from work was 1.6 miles (16). If walking this distance to work were
reinstituted by our obese subjects, all of whom currently drive to work,
an extra 150 kcal per day could be expended. We will need to use similar
measures to promote NEAT as an impetus to create an active and dynamic
environment in which, for example, dancing supersedes television as a
leisure activity. Approaches that succeed in getting people out of their
chairs and moving could have substantial impact on the obesity epidemic.
References and Notes
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3. World Health Organization, Obesity: Preventing and
Managing the Global Epidemic (Geneva, Switzerland, 1997).
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7. J. A. Levine, E. L. Melanson, K. R. Westerterp, J. O.
Hill, Am. J. Physiol. Endocrinol. Metab. 281, E670 (2001).[Abstract/Free
8. Materials and methods are available as supporting
material on Science Online.
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Physiol. 251, R1137 (1986).[ISI][Medline]
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Lanningham-Foster, J. A. Levine, Am. J. Physiol. 286, E551 (2004).[ISI]
12. J. G. Sutcliffe, L. de Lecea, Nature Med. 10, 673
13. C. M. Kotz, personal communication.
14. J. O. Hill, H. R. Wyatt, G. W. Reed, J. C. Peters,
Science 299, 853 (2003).[Abstract/Free Full Text]
15. More information about promoting NEAT in small
increments can be found at www.smallstep.gov and www.americaonthemove.org.
16. L. Lanningham-Foster, L. J. Nysse, J. A. Levine,
Obes. Res. 11, 1178 (2003).[Abstract/Free Full Text]
17. We thank the volunteers, dietitians, food
technicians, nursing staff, and the Mass Spectrometer Core at the General
Clinical Research Center, A. Oberg for assistance with statistics, and P.
Baukol for technical support. Supported by NIH grants DK56650, DK63226,
DK66270, and M01 RR00585, by T. S. and D. B. Ward, and by the Mayo
Supporting Online Material
Materials and Methods
Figs. S1 to S4
Tables S1 and S2
20 October 2004; accepted 7 December 2004
Include this information when citing this paper.
Volume 307, Number 5709, Issue of 28 Jan 2005, pp. 584-586.
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