A NEAT Way to Control Weight?

[Guest guest]

Hi All,

The pdf-available below suggested to me

that losing weight by burning calories may

be why lower weight individuals may not be

the best model of CR. A low BMI may not an

indication of CRON be.

PHYSIOLOGY:

A NEAT Way to Control Weight?

Ravussin

Science 28 January 2005: 530-531.

In a tradition that originated in Babylon 4000 years ago, millions

of us make New Year's resolutions. Such resolutions are often to lose

weight by exercising more and eating less. No doubt, before January

is out, most of us who swore to take a daily walk and pass up that

extra snack have slunk back to our old habits. On page 584 of this

issue, Levine et al. (1) suggest an alternative strategy for weight

control. They offer evidence that differences in postural habits

account for variations in body weight between the lean and the mildly

obese. They propose that fidgeting, may be an unusual method of

weight control.

Six years ago, Levine and co-workers introduced to Science readers

the acronym NEAT, which stands for non-exercise activity

thermogenesis (2). NEAT, we were told, is the energy expended by

physical activities other than planned exercise--sitting, standing,

walking, talking, fidgeting, etc. In their original study, Levine's

group reported that equally overfed volunteers gained different

amounts of weight, a difference that they explained by an

individual's propensity for NEAT (2). Now, in a sequel to this work,

Levine et al. attempt to pin down the source of NEAT that accounts

for this difference in energy economy (1). These investigators

outfitted self-proclaimed " couch potatoes, " both lean and mildly

obese, with arrays of inclinometers and triaxial accelerometers that

continuously measured body posture and movements for 10 days. The

authors' main observation is that obese individuals remained seated

for about 2.5 hours per day longer than the lean " couch potatoes, "

for an average savings of about 350 kcal/day in energy expenditure

(see the figure). As this energy saving was not matched by a similar

decrease in energy intake, Levine et al. calculate that this economy

in energy expenditure would be sufficient for weight gain in the

mildly obese.

In an attempt to determine whether this economy of motion is the

cause or the consequence of obesity, Levine et al. repeated the

study. This time, however, obese participants were put on a diet for

2 months and the lean ones were overfed for 2 months, resulting in a

loss of 8 kg and a gain of 4 kg, respectively. Although these

perturbations were small in magnitude and short in duration, both the

lean and obese maintained their original posture measurements. This

suggests that sedentary habits are biological rather than

environmentally determined.

Obesity has reached epidemic proportions in developed societies,

and billions of dollars are spent on diets and health clubs in a

failing effort to control weight. Weight gain is a dynamic process

that results from a long-term sustained imbalance between energy

intake and energy expenditure. The spectacular increase in the

prevalence of obesity over the past four decades seems to indicate

that environment, rather than biology, drives the epidemic (3). At

present, more than two-thirds of Americans are overweight and 25% are

obese, and it is expected that the prevalence of obesity in the

United States will reach 40% in 2010--and the rest of the world is

rapidly catching up.

A moratorium on sitting. (Left) Total daily energy expenditure

can be divided into three main components: resting metabolic rate

(RMR), thermogenesis, and the cost of physical activity, both planned

(exercise; red) and unplanned (NEAT; green). RMR represents 50 to 70%

of daily energy expenditure and covers the energy necessary for body

maintenance, including cellular metabolism and whole-body functions

such as ventilation, circulation, and tissue oxygen uptake. RMR seems

to be " fixed " for a given person, although it does decline with age.

Because humans have evolved behavioral strategies (clothing) to

maintain body temperature in cold environments, thermogenesis

(yellow) accounts for only 10% of daily energy expenditure and

encompasses the energy required to digest, absorb, transport, and

store ingested food. This leaves 20 to 40% of daily energy

expenditure for the most variable component, physical activity. The

energy cost of physical activity can be divided into planned physical

activity, such as sport and exercise, and spontaneous physical

activity or NEAT, which includes all nonvolitional muscle activities

such as fidgeting, muscle tone, and maintenance of posture. When

people decide to increase energy expenditure for weight control

purposes, usually only structured exercise is included in their

calculations. Levine et al. propose that concentrating on modifying

NEAT behaviors (standing instead of sitting, fidgeting instead of

keeping still, or simply walking) can burn the necessary extra

calories to control weight (1, 2). In other words, targeting

inactivity may be sufficient to fill the " energy gap " that leads to a

creeping up of body weight (6). (Right) Time spent sitting versus

standing and ambulating in 20 self-proclaimed " couch potatoes, " both

lean (top) and mildly obese (bottom) (1). If the obese volunteers

substituted a mere 164 min of sitting for standing or walking around,

they would expend an extra 352 kcal/day on average. This could

prevent the addition of extra pounds, assuming energy intake is

unchanged.

Although humans have evolved thrifty mechanisms to defend energy

stores during times of privation, apparently we have a much harder

time preventing the storage of excess energy in times of affluence.

Since the Second World War, the food industry has mass-produced

increasingly palatable foods (rich in fat and refined carbohydrates)

that are easily accessible and inexpensive. This has promoted

excessive food intake, discouraged physical activity, and promoted

obesity and its related diseases, such as diabetes, dyslipidemia, and

cardiovascular disease.

The major culprit, however, is still not entirely clear: Is it

increased food intake or decreased physical activity? Population data

from Britain suggest that despite a doubling of the prevalence of

obesity in the 1980s, the average energy intake actually declined

over this period. This suggests that the adoption of a modern

inactive life style is at least as important as diet in the etiology

of obesity (4, 5). In this regard, it is worth emphasizing that

the " energy gap " required to explain the increased prevalence of

obesity is only 100 to 200 kcal/day (6). This suggests that a

sustained small change in either energy intake or energy expenditure

is all that is required to prevent obesity in most of us (see the

figure). Therefore, the difference in NEAT observed between obese and

lean individuals is significant and implies that obesity might be

prevented through simply limiting sedentary activities, or increasing

behaviors such as standing, walking, and fidgeting. Indeed, a half-

century ago, Widdowson (7) found that fidgeting is important for

energy expenditure. In a 1986 study, spontaneous physical activity

equivalent to NEAT and measured within the confines of a respiratory

chamber accounted for an average energy expenditure of 348 kcal/day

(8). The energy cost of spontaneous physical activity varied among

study participants from 100 to 700 kcal/day and accounted for a major

portion of individual differences in 24-hour energy expenditure.

Interestingly, these values are almost the same as those reported in

the Levine et al. study in which extra " couch potato " time accounted

for energy savings of 352 kcal/day on average.

The underlying mechanisms responsible for an individual's

propensity to fidget are unknown. However, studies in families (9)

have shown that although the degree of spontaneous physical activity

is highly variable, it is more similar among siblings than among

unrelated individuals. This provides indirect evidence for the idea

that NEAT is genetically determined. Furthermore, in a prospective

study, weight gain was inversely related to the level of NEAT, at

least in males (9). Unfortunately, if genes do determine the

true " coach potato, " then encouraging an exchange of time spent

sitting for time spent standing, as suggested, is unlikely to help to

control body weight. Instead, one could progressively change the

environment to discourage sitting behaviors. What Levine and

colleagues clearly demonstrate is that small but sustained changes in

the activities of daily living can profoundly affect energy balance.

References

J. A. Levine et al., Science 307, 584 (2005).

J. A. Levine et al., Science 283, [212] (1999).

J. O. Hill, J. C. s, Science 280, [1371] (1998).

A. M. Prentice, S. A. Jebb, Br. Med. J. 311, 437 (1995) [Medline].

M. et al., Int. J. Obes. Relat. Metab. Disord. 29, 151 (2005)

[Medline].

J. O. Hill et al., Science 299, [853] (2003).

E. M. Widdowson et al., Br. J. Nutr. 8, 147 (1954) [Medline].

E. Ravussin et al., J. Clin. Invest. 78, 1568 (1986) [Medline].

F. Zurlo et al., Am. J. Physiol. 263, E296 (1992) [Medline].

Interindividual Variation in Posture Allocation: Possible Role in

Human Obesity

A. Levine, Lorraine M. Lanningham-, K. McCrady,

Alisa C. Krizan, R. Olson, H. Kane, D. Jensen,

and M.

Science 28 January 2005: 584-586.

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.

-------------------------------------------------------------------

-------------

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, and talking.

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 movement (ambulation).

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).

----------------------------------------------------------------------

----------

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.

----------------------------------------------------------------------

----------

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 investigation.

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.

[Guest guest]

I like the article in that it begins to attack the real mechanisms behind obesity.

People become obese because they eat more than they burn - a rather simplistic generalization describing something we don't know much about. Of course it's true, but mammals excrete a fairly large amount of calories and that is never taken into account. Only one person in the CR groups has done a bomb calorimeter test on feces, ie, not a lot of data in the obesity discussions.

Cattle, eg, excrete 17% of intake. So why doesn't our body use ALL of the kcals and reduce the feces to tiny balls as I see in deer, goats, rabbits? Just thinking about that makes me uncomfortable. Maybe it's because they eat a lot of fiber. Maybe the fiber mediates how much we absorb. Maybe it's the low nutrient content of their browse.

Also, probably not everyone has the same absorption factor, and probably the absorption factor changes with age.

Another thing is, as stated the RMR decreases with age, so a 35 yo eating 1600 kcals will weigh 110# (harris-benedict)expending 200 kcals routine exercise, while a 69 yo will weigh 145# doing the exact same exercise. Each year the intake req't falls 7 kcals for me. That's a half pound added next year and a pound the following year, and so on, if I don't cut calorie intake. So if we compensate by "small but sustained changes in the activities of daily living" have to be increased each year by 7 kcals per day.

I wonder if typing this note equates to fidgeting?

Regards.

----- Original Message -----

From: old542000

Sent: Friday, January 28, 2005 8:31 PM

Subject: [ ] A NEAT Way to Control Weight?

Hi All, The pdf-available below suggested to methat losing weight by burning calories maybe why lower weight individuals may not bethe best model of CR. A low BMI may not anindication of CRON be. PHYSIOLOGY:A NEAT Way to Control Weight? RavussinScience 28 January 2005: 530-531. In a tradition that originated in Babylon 4000 years ago, millions of us make New Year's resolutions. Such resolutions are often to lose weight by exercising more and eating less. No doubt, before January is out, most of us who swore to take a daily walk and pass up that extra snack have slunk back to our old habits. On page 584 of this issue, Levine et al. (1) suggest an alternative strategy for weight control. They offer evidence that differences in postural habits account for variations in body weight between the lean and the mildly obese. They propose that fidgeting, may be an unusual method of weight control. Six years ago, Levine and co-workers introduced to Science readers the acronym NEAT, which stands for non-exercise activity thermogenesis (2). NEAT, we were told, is the energy expended by physical activities other than planned exercise--sitting, standing, walking, talking, fidgeting, etc. In their original study, Levine's group reported that equally overfed volunteers gained different amounts of weight, a difference that they explained by an individual's propensity for NEAT (2). Now, in a sequel to this work, Levine et al. attempt to pin down the source of NEAT that accounts for this difference in energy economy (1). These investigators outfitted self-proclaimed "couch potatoes," both lean and mildly obese, with arrays of inclinometers and triaxial accelerometers that continuously measured body posture and movements for 10 days. The authors' main observation is that obese individuals remained seated for about 2.5 hours per day longer than the lean "couch potatoes," for an average savings of about 350 kcal/day in energy expenditure (see the figure). As this energy saving was not matched by a similar decrease in energy intake, Levine et al. calculate that this economy in energy expenditure would be sufficient for weight gain in the mildly obese. In an attempt to determine whether this economy of motion is the cause or the consequence of obesity, Levine et al. repeated the study. This time, however, obese participants were put on a diet for 2 months and the lean ones were overfed for 2 months, resulting in a loss of 8 kg and a gain of 4 kg, respectively. Although these perturbations were small in magnitude and short in duration, both the lean and obese maintained their original posture measurements. This suggests that sedentary habits are biological rather than environmentally determined. Obesity has reached epidemic proportions in developed societies, and billions of dollars are spent on diets and health clubs in a failing effort to control weight. Weight gain is a dynamic process that results from a long-term sustained imbalance between energy intake and energy expenditure. The spectacular increase in the prevalence of obesity over the past four decades seems to indicate that environment, rather than biology, drives the epidemic (3). At present, more than two-thirds of Americans are overweight and 25% are obese, and it is expected that the prevalence of obesity in the United States will reach 40% in 2010--and the rest of the world is rapidly catching up. A moratorium on sitting. (Left) Total daily energy expenditure can be divided into three main components: resting metabolic rate (RMR), thermogenesis, and the cost of physical activity, both planned (exercise; red) and unplanned (NEAT; green). RMR represents 50 to 70% of daily energy expenditure and covers the energy necessary for body maintenance, including cellular metabolism and whole-body functions such as ventilation, circulation, and tissue oxygen uptake. RMR seems to be "fixed" for a given person, although it does decline with age. Because humans have evolved behavioral strategies (clothing) to maintain body temperature in cold environments, thermogenesis (yellow) accounts for only 10% of daily energy expenditure and encompasses the energy required to digest, absorb, transport, and store ingested food. This leaves 20 to 40% of daily energy expenditure for the most variable component, physical activity. The energy cost of physical activity can be divided into planned physical activity, such as sport and exercise, and spontaneous physical activity or NEAT, which includes all nonvolitional muscle activities such as fidgeting, muscle tone, and maintenance of posture. When people decide to increase energy expenditure for weight control purposes, usually only structured exercise is included in their calculations. Levine et al. propose that concentrating on modifying NEAT behaviors (standing instead of sitting, fidgeting instead of keeping still, or simply walking) can burn the necessary extra calories to control weight (1, 2). In other words, targeting inactivity may be sufficient to fill the "energy gap" that leads to a creeping up of body weight (6). (Right) Time spent sitting versus standing and ambulating in 20 self-proclaimed "couch potatoes," both lean (top) and mildly obese (bottom) (1). If the obese volunteers substituted a mere 164 min of sitting for standing or walking around, they would expend an extra 352 kcal/day on average. This could prevent the addition of extra pounds, assuming energy intake is unchanged. Although humans have evolved thrifty mechanisms to defend energy stores during times of privation, apparently we have a much harder time preventing the storage of excess energy in times of affluence. Since the Second World War, the food industry has mass-produced increasingly palatable foods (rich in fat and refined carbohydrates) that are easily accessible and inexpensive. This has promoted excessive food intake, discouraged physical activity, and promoted obesity and its related diseases, such as diabetes, dyslipidemia, and cardiovascular disease.The major culprit, however, is still not entirely clear: Is it increased food intake or decreased physical activity? Population data from Britain suggest that despite a doubling of the prevalence of obesity in the 1980s, the average energy intake actually declined over this period. This suggests that the adoption of a modern inactive life style is at least as important as diet in the etiology of obesity (4, 5). In this regard, it is worth emphasizing that the "energy gap" required to explain the increased prevalence of obesity is only 100 to 200 kcal/day (6). This suggests that a sustained small change in either energy intake or energy expenditure is all that is required to prevent obesity in most of us (see the figure). Therefore, the difference in NEAT observed between obese and lean individuals is significant and implies that obesity might be prevented through simply limiting sedentary activities, or increasing behaviors such as standing, walking, and fidgeting. Indeed, a half-century ago, Widdowson (7) found that fidgeting is important for energy expenditure. In a 1986 study, spontaneous physical activity equivalent to NEAT and measured within the confines of a respiratory chamber accounted for an average energy expenditure of 348 kcal/day (8). The energy cost of spontaneous physical activity varied among study participants from 100 to 700 kcal/day and accounted for a major portion of individual differences in 24-hour energy expenditure. Interestingly, these values are almost the same as those reported in the Levine et al. study in which extra "couch potato" time accounted for energy savings of 352 kcal/day on average. The underlying mechanisms responsible for an individual's propensity to fidget are unknown. However, studies in families (9) have shown that although the degree of spontaneous physical activity is highly variable, it is more similar among siblings than among unrelated individuals. This provides indirect evidence for the idea that NEAT is genetically determined. Furthermore, in a prospective study, weight gain was inversely related to the level of NEAT, at least in males (9). Unfortunately, if genes do determine the true "coach potato," then encouraging an exchange of time spent sitting for time spent standing, as suggested, is unlikely to help to control body weight. Instead, one could progressively change the environment to discourage sitting behaviors. What Levine and colleagues clearly demonstrate is that small but sustained changes in the activities of daily living can profoundly affect energy balance.