Activity not food intake most strong correlated with weight gain in adulthood

[Paleoanth]

http://www.ohsu.edu/activitylevels/

OHSU Research Reveals Activity Levels—Not Food Intake—Most Strongly Correlates With Weight Gain In Adulthood
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PORTLAND, Ore. – Research conducted at the Oregon National Primate Research Center reveals that an individual’s activity level is the most constant factor in predicting weight gain over adulthood. In addition, the research startlingly found no strong correlation between caloric intake and weight gain. The research was released online this week prior to future publication in the American Journal of Physiology: Regulatory, Integrative and Comparative Physiology.

“Many Americans believe that diet and weight gain are closely linked,” explained Judy Cameron, Ph.D., a senior scientist in the divisions of reproductive sciences and neuroscience at the OHSU Oregon National Primate Research Center. “Although in general terms, increasing food intake has the potential of increasing body weight, this does not appear to be the primary cause of weight gain during the adult years. An individual’s activity level appears to far outweigh diet in regards to the factors impacting body weight. This is especially important to middle-aged Americans who typically witness a jump in weight. ”

Previous studies in other animal models have also suggested a connection between weight gain and activity levels. However, those studies failed to demonstrate whether reduced activity level is a cause of obesity or a consequence of it.

To conduct the current research project , Cameron and her colleagues studied 18 adult female monkeys over a 9 month period. Approximately one year prior to the research, the animals had their ovaries removed, which effectively simulates menopause in women. Also, for a year prior to the study, all of the animals were placed on a high fat diet, closely mimicking that of a middle-aged woman in the Western world.

Throughout the study, each animals’ food intake, body weight and body fat were tracked on a regular basis. In addition, researchers tracked the activity levels of the individual animals by way of a small device called an accelerometer which was worn on a collar around each monkey’s neck.

“After nine months of observation we noticed some significant trends,” explained Elinor Sullivan, a graduate student in the Cameron lab. “For instance, there was a wide variety of activity levels amongst the animals in the study (an 8-fold difference between the most active and most sedentary monkeys.) Secondly, animals that were initially the most active remained the most active at the end of the study. This suggests that activity level is in inherent trait for each individual. Thirdly, the activity level – not the amount of calories ingested – was the strongest predictor of whether an animal would gain weight.”

“When compared to humans, these findings in monkeys offer tremendous insights into the obesity crisis many middle-aged Americans are facing,” added Cameron. “More than 60 percent of Americans do not participate in the recommended amount of physical activity and 25 percent are considered inactive. Considering the fact that 60 percent of adult Americans are overweight or obese this is a finding that affects a large percentage of the adult population in this country. Of course the complicating factor in all of this is the fact that the body often compensates for increases in exercise by potentially altering non-exercise energy expenditure. So while we can say that exercise is effective, the body is actually working against you in many ways to prevent weight loss”

“This study demonstrates the inherent benefit of becoming and staying active on body weight,” said Jonathan Purnell, M.D. an associate professor of medicine (endocrinology, diabetes and clinical nutrition) in the OHSU School of Medicine and a researcher in OHSU's Center for the Study of Weight Regulation and Associated Disorders. “Scientists and physicians need to better understand the reasons for differences in baseline activity levels between individuals and how this physiology might make one more or less susceptible to unwanted weight gain.”

The ONPRC is a registered research institution, inspected regularly by the United States Department of Agriculture. It operates in compliance with the Animal Welfare Act and has an assurance of regulatory compliance on file with the National Institutes of Health. The ONPRC also participates in the voluntary accreditation program overseen by the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC).

[Paleoanth]

I think that many people on this forum would disagree.

[liddie01]

I know it wasn't true for me :lol: My job entails climbing motor home chassis all day, sometimes 16 motorhomes, so at least 32-45 times to install plumbing and quite a lot of fast walking when i am working, and still I got fatter and fatter. :lol:

[eepobee]

Also, for a year prior to the study, all of the animals were placed on a high fat diet, closely mimicking that of a middle-aged woman in the Western world.the overwhelming majority of middle-aged women in the "Western world" are not on high-fat diets; they're on high-carb diets.

[ValerieL]

Well, it makes some sense to me. Isn't exercise supposed to help insulin resistance? It kind of makes sense to me that an active person (monkey) would be less likely to develop insulin resistance and gain weight from the high fat/high carb diet than the inactive one.

It's not the whole answer, but it might be part of it.

[kaypeeoh]

Hi-calorie is hi-calorie regardless of whether it's carb-based or not. Metabolic rates differ within groups. In my family my dad is thin, my mom is heavy. Two of my brothers are thin like dad but my sister and I are heavy like mom. Obviously we grew up eating the same. My brothers have always been more active but at the same time tended to eat less and snack less than my sister and I.

[kwikdriver]

Well, it makes some sense to me. Isn't exercise supposed to help insulin resistance? It kind of makes sense to me that an active person (monkey) would be less likely to develop insulin resistance and gain weight from the high fat/high carb diet than the inactive one.

It's not the whole answer, but it might be part of it.


From what I can tell they imply they controlled for calories (how could they not?), so I'm not sure how insulin resistance would play a role. We are told that what it does with humans is turn on the eating switch so you eat more; if they controlled for food intake, then (and again, how in the world could they not?), I don't see how insulin resistance on its own could be responsible for weight gain.

I'm going to keep an eye out for the original research when it's actually published, because I keep going over this in my mind and I have about a billion questions (like how they controlled for food intake) that aren't answered in this article. My own guess is that it has to do with metabolism, and the effect being active has on maintaining muscle mass, but it's only a guess. :)

[Alleine]

It makes total sense to me. While growing up in New York City, I walked everywhere, climbed many flights of subway stairs and was constantly on the go. When I moved to a place where I drove everywhere I gained 40 lbs in one year without changing my eating habits. Activity level matters A LOT.

[ValerieL]

From what I can tell they imply they controlled for calories (how could they not?), so I'm not sure how insulin resistance would play a role. We are told that what it does with humans is turn on the eating switch so you eat more; if they controlled for food intake, then (and again, how in the world could they not?), I don't see how insulin resistance on its own could be responsible for weight gain.

My understanding is that one of the basic premises of low-carbing is that insulin is the fat storage hormone. In addition to clearing out the sugar from your blood, causing a drop which causes hunger, insulin is key in the mechanism where food energy is converted to fat. Insulin resistance would be very responsible for weight gain then because with excess insulin in our blood, it's working overtime to make fat.

[kwikdriver]

My understanding is that one of the basic premises of low-carbing is that insulin is the fat storage hormone. In addition to clearing out the sugar from your blood, causing a drop which causes hunger, insulin is key in the mechanism where food energy is converted to fat. Insulin resistance would be very responsible for weight gain then because with excess insulin in our blood, it's working overtime to make fat.


But you still need an excess of energy (food) in order to store fat. From reading this, I'm lead to believe food intake remained constant, but again, I can't tell from this.

If the group of monkeys that grew fatter also ate more, it would make the whole research nonsensical (Eating more makes you fat, which is the opposite of what they are saying here); if the fat monkeys just stopped exercising and gained weight, again, it makes the research meaningless (exercise less and gain weight, oooh, what a shock). Again, I want to see the research, because I'm just scratching my head. The problem at this point is this was a poorly written piece.

[Lessara]

I believe what makes us fat is a whole host of reasons.
I know for me exercise in my youth kept me normal weight and when I went to college with unlimited carbs and very busy days lead me to limited exercise. I actually took a gym course (racketball) do give me time to exercise. When came children and full time work. I never exercised regularly since my teen years. I miss it. Now I'm so big its hard to go for long walks and such.

Oh the reason for my weight gain? Insulin resistance ---> type II Diabetes and low thyroid function.

[Paleoanth]

I'm going to keep an eye out for the original research when it's actually published, because I keep going over this in my mind and I have about a billion questions (like how they controlled for food intake) that aren't answered in this article. My own guess is that it has to do with metabolism, and the effect being active has on maintaining muscle mass, but it's only a guess. :)

I am too. I was alerted to this by my supervisor at work. This was all I could find on the research. From what he could tell me, and I am hoping he can find what he read or heard, they gave the monkeys the exact same food and the more active ones ate less than the other monkeys. But again, this is what he told me, and not what the piece I found specifies.

[Gretchen_]

http://ajpregu.physiology.org/cgi/reprint/00069.2006v1

this is a link to the full text PDF. I'm not sure if I can access it because I'm at a university.


Here's is the abstract
http://ajpregu.physiology.org/cgi/content/abstract/00069.2006v1. From the abstract page there is a link to the full text PDF if there is a problem accessing it.

[ValerieL]

But you still need an excess of energy (food) in order to store fat. From reading this, I'm lead to believe food intake remained constant, but again, I can't tell from this.

I think you are thinking a little too linearly here. If excess insulin is so very efficient at making fat, then excess insulin itself alters metabolism (loosely defined as caloric expenditure here). Back to that idea that you can measure input accurately, but every little thing in your body that changes minute to minute changes output. My understanding is that excess insulin changes the output side of the equation.

[Scars]

This is absolutely bang-on... not to take anything away from the importance of the nutritional factors, but activity seems to be the tried and true predictor. We needn't look any further than the Amish Paradox. 18000 steps/day for men, 14000 for women (on avg.) Their diets are generally speaking, quite high in refined carbs - breads, pastries, pies, etc and yet less than 4% of Amish people are obese.

Another example - Colorado has the lowest obesity rate in the country at 16%. Tennessee has the highest at 25%. The difference? You guessed it: A study showed that people in Colorado walk more. Tennesseans apparently walk only to the fridge and the couch.

Exercise is likely the #1 factor in improving insulin sensitivity. Every hour a day of brisk walking has been linked to a 34% lower risk of diabetes. Also, the combination of exercise and weight loss (7% of body weight), correlated to a 58% lower incidence of diabetes, compared to those who didn't exercise or lose weight (granted, we don't know how much of this was the exercise vs. weight loss).

References:
JAMA 289: 1785, 2003
New England Journal of Medicine 34:393, 2002

[Paleoanth]

I cannot get to the article, just the abstract:

"In contrast, food intake did not correlate with weight gain and there was no difference in weight gain between the monkeys with the highest versus the lowest caloric intake, total metabolic rate, or basal metabolic rate. "

[kwikdriver]

This is absolutely bang-on... not to take anything away from the importance of the nutritional factors, but activity seems to be the tried and true predictor. We needn't look any further than the Amish Paradox. 18000 steps/day for men, 14000 for women (on avg.) Their diets are generally speaking, quite high in refined carbs - breads, pastries, pies, etc and yet less than 4% of Amish people are obese.

The Amish also don't eat much (if any) fast food or junk food. In fact, they eat a diet very similar to the one eaten in this country before WWII, which was before the explosion of cheap, highly refined foods hit the market.

I have no problem with the idea that exercise can stave off weight gain (in the aggregate), or is good for health -- it's kind of a no duh proposition. I do have problems with the way this research is being presented here, which basically raises more questions than it answers. OK, it was written poorly, we'll have to let that go until the real stuff is published, hopefully next month. But I have even bigger problems with the use I can see research like this being put to. Because it plays into already accepted notions about the overweight (lazy), I can see a whole lot of people with a certain mindset fastening on to this and running with it for all it's worth. And "in the aggregate" doesn't cover the whole range of people who are overweight. It's going to be very easy for people to take research like this and sweep the obesity problem under a rug and blame the obese by saying, "Get off your fat asses and exercise," or everyone's favorite, "Eat less and exercise more." And the problem is more complex than that.

[kwikdriver]

Here's (http://ajpregu.physiology.org/cgi/content/abstract/00069.2006v1) the abstract, if anyone wants to read it:

The increased prevalence of overweight adults has serious health consequences. Epidemiological studies suggest an association between low activity and being overweight, however, few studies have objectively measured activity during a period of weight gain so it is unknown whether low activity is a cause or consequence of being overweight. To determine whether individual differences in adult weight gain are linked to an individual's activity level we measured activity, via accelerometry over a prolonged period (9 months) in 18 adult female rhesus monkeys. Weight, food intake, metabolic rate and activity were first monitored over a 3-month period. During this period, there was mild but significant weight gain (5.5 ± 0.88%; t =-6.3, df=17, p<0.0001), while caloric intake and activity remained stable. Metabolic rate increased, as expected, with weight gain. Activity level correlated with weight gain (r=-0.52, p=0.04) and the most active monkeys gained less weight than the least active monkeys (t =-2.74, df=8, p=0.03). Moreover, there was an 8-fold difference in activity between the most and least active monkeys, and initial activity of each monkey was highly correlated with their activity after 9 months (r=0.85, p<0.0001). In contrast, food intake did not correlate with weight gain and there was no difference in weight gain between the monkeys with the highest versus the lowest caloric intake, total metabolic rate, or basal metabolic rate. We conclude that physical activity is a particularly important factor contributing to weight change in adulthood and that there are large, but stable, differences in physical activity among individuals.

There isn't enough information to answer most of my questions. Food intake and metabolism remained constant, so insulin resistance doesn't sound like a likely culprit: it looks like the calories burned from the exercise itself was what caused the active monkeys to gain less weight. Basically, it's saying exercise more, weigh less. Wow, what a surprise. Your tax dollars at work.

[Scars]

Well said, quickdriver... I agree with your contensions wrt the manner in which the study was conducted.

[Fialka]

I'm another of those who exercised and exercised and exercised and never lost a pound. I actually taught a kickboxing class to a group of thinner-than-me women and no one could walk after the 180 squats and lunges we did but me. I was totally in shape and doing my darndest to outrun my fat, but it never worked.

Scientists need to start realizing that their research should also be focusing on those who are glucose intolerant. Study designs consistently assume everyone is the same and discount a large percentage of the population and not just with insulin resistance, but hypthyroidism and other metabolic conditions.

But that would probably screw up their funding from Kraft and Nabisco and the like and we wouldn't want that, would we?

F

[ItsTheWooo]

From what I can tell they imply they controlled for calories (how could they not?), so I'm not sure how insulin resistance would play a role. We are told that what it does with humans is turn on the eating switch so you eat more; if they controlled for food intake, then (and again, how in the world could they not?), I don't see how insulin resistance on its own could be responsible for weight gain.

The majority of weight gain associated with insulin resistance is from over eating, but not all of it. It changes the way you metabolize food, by changing the balance of metabolic hormones, which change enzyme expression... end result is that the food you eat is more likely to wind up as fat and less likely to wind up energy or heat. I gain weight on very few high carb cals, it takes much more low carb food to make me gain.

[ItsTheWooo]

But you still need an excess of energy (food) in order to store fat. From reading this, I'm lead to believe food intake remained constant, but again, I can't tell from this.

If the group of monkeys that grew fatter also ate more, it would make the whole research nonsensical (Eating more makes you fat, which is the opposite of what they are saying here); if the fat monkeys just stopped exercising and gained weight, again, it makes the research meaningless (exercise less and gain weight, oooh, what a shock). Again, I want to see the research, because I'm just scratching my head. The problem at this point is this was a poorly written piece.

Insulin is the guy who controls fat making enzymes and whether or not we synthesize energy from our tissues. You can eat the same calories, but if your metabolism is not working well then you may gain fat, whereas others who have better working metabolisms won't (because of lower insulin levels from more activity). Insulin makes fat and shuts off synthesis of energy from fat/protein by shutting of glucagon. Result is fatness and lethargy. Fat people with insulin resistance have low energy for a reason.
On the other hand, sensitivity to insulin means less fat making, more energy making. Thin people tend to get really hot after eating for a reason.

Even if we assume one is energy restricted or eating normal cals, if insulin is *too high* you still will make less energy and more fat and thus get fat.

[ItsTheWooo]

I think you are thinking a little too linearly here. If excess insulin is so very efficient at making fat, then excess insulin itself alters metabolism (loosely defined as caloric expenditure here). Back to that idea that you can measure input accurately, but every little thing in your body that changes minute to minute changes output. My understanding is that excess insulin changes the output side of the equation.
Righto.

Paleoanth just said that the active monkeys may have also eaten less, and if that's true, then I'm certain it must have to do with greater insulin sensitivity in the active monkies. (as well as the actual reduction in cals)

[potatofree]

I'm thinking about the whole chicken/egg aspect of it all. As it said, it's hard to tell if decreased activity is a cause or effect of being overweight.

My naturally bony ex-SIL is always on the move, and even though she eats a lot, she can't gain weight. (I still think the evil inside her burns a LOT of calories...) If I tried to match her activity level, my knees would give out and I'd be too tired to move halfway through the day....

[ItsTheWooo]

Here's (http://ajpregu.physiology.org/cgi/content/abstract/00069.2006v1) the abstract, if anyone wants to read it:



There isn't enough information to answer most of my questions. Food intake and metabolism remained constant, so insulin resistance doesn't sound like a likely culprit: it looks like the calories burned from the exercise itself was what caused the active monkeys to gain less weight. Basically, it's saying exercise more, weigh less. Wow, what a surprise. Your tax dollars at work.

Oh.
Well isn't that stupid.

[ceberezin]

They tracked total calories, but made no allowance for the source of the calories. All of the monkeys were on a high fat diet, so, presumably they were not stimulating a lot of insulin which would lead to fat storage, assumung that simian metabolism is similar to human metabolism in this regard, never a safe assumption. Would activity levels have been such a prominent feature of the results if one group of monkeys ate high fat and another group ate high carb?

Secondly, the abstract talks about differences in caloric intake only in relative terms. Some monkeys had a higher caloric intake than others, but we have no information on how much higher it might have been. Having removed a number of factors which might affect metabolic rates and weight gain, they assume that the cause of the weight gain was the factor they allowed to remain. It doesn't follow.

This study is really about the role of activity levels in weight gain in monkeys on a relatively isocaloric high fat diet. I see nothing here that would justify any speculation as to absolute factors for weight gain in humans.

[TBoneMitch]

Cerebezin,

you have to know that in nutritional research, a high-fat diet really means (as Valerie pointed out) a high-fat HIGH CARB diet. We're talking around 40% fat and 40-50% carbs usually.

But the high fat part gets singled out.

[eepobee]

i didn't have a chance to read it yet, but anyone interested in reading the article can find it here (http://www.geocities.com/eepobee/00069.2006v1.pdf) as a .pdf file.