Friday, September 12, 2008

Inactivity and Weight Gain

Most of the papers I read in the field pay lip-service to some familiar stories: thrifty genes; calories in, calories out; energy density; fat intake; gluttony and sloth.

It may sound counterintuitive, but how do we know that inactivity causes overweight and not the other way around?  In other words, isn't it possible that metabolic deregulation could cause both overweight and a reduced activity level? The answer is clearly yes. There are a number of hormones and other factors that influence activity level in animals and humans. For example, the "Zucker fatty" rat, a genetic model of severe leptin resistance, is obese and hypoactive (I wrote about it here). It's actually a remarkable facsimile of the metabolic syndrome. Since leptin resistance typically comes before insulin resistance and predicts the metabolic syndrome, modern humans may be going through a process similar to the Zucker rat.

Back to the paper. Dr. Nicholas Wareham and his group followed 393 healthy white men for 5.6 years. They took baseline measurements of body composition (weight, BMI and waist circumference) and activity level, and then measured the same things after 5.6 years. In a nutshell, here's what they found:
  • Sedentary time associates with overweight at any given timepoint. This is consistent with other studies.
  • Overweight at the beginning of the study predicted inactivity after 5.6 years.
  • Inactivity at the beginning of the study was not associated with overweight at the end.
In other words, overweight predicts inactivity but inactivity does not predict overweight. With the usual caveat that these are just associations, this is not consistent with the idea that inactivity causes overweight. It is consistent with the idea that overweight causes inactivity, or they are both caused by something else.


Drs. Cynthia and David said...

Thanks Stephan. We certainly have had the same experience (exercising more causes increased hunger) and seems to actually interfere with our weight loss efforts, though it's hard to tell how much is just "overhydration" after longer events from how much is genuine increased hunger. I wish people would be more careful about deconvoluting cause and effect. At least this guy asked the right questions!

Robert Andrew Brown said...

Thanks Stephan - another fascinating topic.

By complete coincidence through this blog and its links last night I found and watched Gary Taubes video lecture. I found it thought provoking and instructional particularly in the use of photographic material and back to basics approach.

I believe I have identified the missing factor that answers all of the questions, and provided an outline as to why.

It is all in the book and has taken three years of being a complete nerd to see a simple truth.

The crux of the answer is the excess intake of Omega Six exacerbated by a lack of Omega 3 and related marine minerals.

In essence I suggest;

Omega six is scarce in the natural environment. It occurs in high amounts in seasonal plant reproductive material seeds grain etc.

***** Omega 6 is a measure of the fecundity of the earth. ******

Omega 6 would never have been available in the quantities it is today in a natural diet. We need maybe 1/2% of calories as Omega 6 and generously 1% (But in today's world of poor digestion depleted diet, etc it may be a little more (we do not know) and need rises in pregnancy.

Omega 3 was limited only by access to sea / coastal / aquatic foods, and was available year round. Omega 3 DHA increases metabolism.

Omega 6 is heavily stored as body fat rising from 5-7% in the 1950s to up to 30+% today in some (USA average about 18%). Omega 3s are not significantly stored no matter how high the intake.

Omega 6 in plant reproductive material comes with sugars and carbohydrates. Plant reproductive material is in dietary terms a fertility assisting hormone raw material and energy storage package.

Omega 6 controls hormone and steroid production through the enzymes of the cholesterol pathways. Fat stores are necessary to successful reproduction to provide a stable supply of Omega 6 for hormone production, and to supply the cellular structural needs of babies.

It would be logical if omega 6 instructed the body to store fat. Omega 6 was a very scarce material essential to reproduction.

It was also a measure of the likely environmental food availability and so a measure of the chance of a successful pregnancy. It would be a good survival strategy to have a mechanism to link reproduction to environmental fecundity.

Omega 6 encourages fat storage by a number of mechanisms including reduction of metabolism, creating an insulin blocking loop and bringing more fat cells on line.

Omega 6 encouraging fat deposition would explain why storage continues in the face of energy intake decline. Whilst excess Omega 6 is present I suggest the body metabolism is set to store.

Reproduction is a key aim of any species, and so store Omega 6 would be a prime directive.

It would explain why children are under weight and adults over weight. Children have a high demand for Omega 6 to build cell membranes and so would use reasonable excess. In full grown adults demand for new vascular systems brain growth etc which all demand Omega 6 would have almost ceased so allowing the accumulation of Omega Six and the signal to store.

Large excess of omega 6 results in obesity at very early ages. ( Our intake is now 10 or more times our nutritional need.)

I also suggest an insulin blocking mechanism that would contribute to obesity and cause metabolic syndrome.

Clearly excess carbohydrates are an issue as is poor quality diet as the whole body works in synergy but arguably excess Omega 6 is capable of explaining the current obesity crisis and the rise in related inflammatory western conditions and neurological decline.

Robert Andrew Brown

Author Omega Six The Devils Fat.

Stephan Guyenet said...

Cynthia and David,

I'm glad to hear that agrees with your experience.


I like your ideas. You know another thing that fits in pretty well with the n-6/energy storage theory is fructose. Fructose tends to become abundant in the fall and is turned directly into fat by the liver. Maybe that's another example of a mechanism we've evolved to fatten up during the season of abundance (and for the winter as well).

Thackray said...

Robert, Steven,

Interesting lay article re plant physiology with regard to Omega 3,6 synthesis, movement and storage.

Supports the concept of omega 6 as a fall storage device for plants and the animals that eat the plants.,b5PRNLJ0,w

Philip Thackray

Robert Andrew Brown said...

Thanks Stephan,

Yes I spotted that possibility too and its in the book. I am glad it makes sufficient sense to have occurred to some one else too.

Thanks Thackray for posting that link. I had seen it a while a ago and it was Susan Allport's book that got me thinking about metabolism and tracking down more information on metabolic rates, mitochondrial function, hibernation etc.

I had forgotten Susan's observation that plants conserve fats by withdrawing them from the leaves.

Again many thanks

Robert Brown

Author; Omega Six The Devils Fat

Meighen said...

Hi Stephen

This is off topic, but I thought you, and maybe some of your readers, would be interested: (Couldn't find any other way to contact you.)

Thank you for your work, which I check in on, and learn from, daily.


Thackray said...


Check out Peter’s blog at

In several of his posts he makes a strong case against fiber.

Philip Thackray

Meighen said...

Thanks, Philip.

I have seen those posts on Peter's blog, and I read "Fiber Menace" last year and made changes in my diet.

The author's video about fiber not contributing to heart health is new so I wanted to let anyone who might be interested know about it.

I like Peter's site, too, but I don't have the mental energy to deal with most of it; Stephan's site is easier for me to understand.

Stephan Guyenet said...


Interesting article. It makes sense now why plants store energy as n-6: low enough melting temperature for colder climates, more stable than n-3.

Stephan Guyenet said...


I checked out the link. I half-agree with what he says. I don't think plant fiber is the panacea it's been portrayed as. But it's also part of the diet of some (but not all) healthy cultures. I think it's probably mostly inert to a healthy person.

But "fiber" is actually many different things. So while the fiber from vegetables and fruit is probably fine in moderation, grain fiber can be problematic because it's packed with nasty toxins. The best way to get rid of the toxins (mostly) is to do what cultures have done to seeds since the beginning of time: soak, sprout, ferment and/or toast them.

Humans have very finicky digestive systems compared to our closest living relatives. We only eat low-fiber, energy-dense foods compared to monkeys and apes. We don't extract energy from fiber by fermenting it in the colon like they can. I suppose we evolved that way because we're damned good at getting the best resources out of whatever niche we occupy. That means digging up starchy roots and hunting fatty animals, rather than chewing on leaves all day.

Peter said...

Just back on lipids, temperatures and seasons for a moment:

If I could throw in the role of vitamin D. From a temperocentric view point we (should) get our max dose of both fructose and omega sixes in the autumn, along side maximum D3 levels. Makes sense to down regulate the inflammatory process with D3 to counterbalance the pro inflammatory effects of fructose and linoleic acid... Somehow I doubt this is just chance.

Possibly less important in the tropics...


Thackray said...

Stephen said

“We don't extract energy from fiber by fermenting it in the colon like they can.”

I think you are referring to fibers like cellulose and hemicellulose from forages that grazing animals can break down (via fermentation not digestion) into volatile fatty acids. This is a major energy source for such animals.

There are of course fibers which we humans can ferment in the colon. They also become short chain fatty acids which can enter the blood stream (energy for the body) and feed the cells of the colon as well and feed the bacteria themselves.

The last fact leads to the somewhat scary concept that hungry gut bacteria can actually make US eat when THEY are hungry!!! Peter describes that process here:

It’s another case against excess fiber intake.

Philip Thackray

Stephan Guyenet said...


It's a matter of degree. Apes and monkeys get a large portion of their calories through colonic fermentation, whereas humans only get a small amount. Most fiber passes out the other end untouched, because our colons aren't big fermentation tanks like theirs.

Stephan Guyenet said...


That's a logical idea. I also wonder if things are different in the tropics.

Thackray said...

Steven said,

“That's a logical idea. I also wonder if things are different in the tropics.”

For one thing, more saturated fats - less omega 6. Points again toward a role for omega 6 in seasonal fatting (which would not be as important in the topics).

While our colons are small and the energy we derive from colon fermentation is also small, what does or doesn’t happen there can be quite important. Peter’s posts that I listed above are just one example of the influence gut bacteria has on us. Evolution probably retained the colon for its moisture removal function but the interaction between the colon, the greater body and the colon bacteria could not be evolved away. So we are left with colon functions that may or may not be beneficial.

Philip Thackray

Stephan Guyenet said...


A good point about seasonal fattening in response to fat composition. Do you know if that theory has been tested?

I agree that what happens in the colon isn't necessarily irrelevant. I just think the idea that fiber is inherently good or bad is simplistic. Humans have been very healthy eating high-fiber and low-fiber diets.

Anna said...

I read The Fiber Menace a year or so ago, and I am in agreement with Stephan. FM makes some interesting points about fiber, some of which probably have some merit, but certainly not all. Plus, the author makes some astoundingly inaccurate statements about the final days of Dr. Atkins' life and health, in a way that suggests a huge grudge against Dr. Atkins. That lessened my impression of the author quite a bit, and of his assertions about fiber.

The book was rather excruciating to read because of the repetition and poor editing, as well. My takeaway view was there was little reason to avoid absolutely all fiber, particularly fiber from non-starchy veggies. Avoiding grain fiber, I can accept.

Thackray said...

Steven, Robert, Peter

Steven said:
“A good point about seasonal fattening in response to fat composition. Do you know if that theory has been tested?”

No I don’t. Maybe Robert Brown knows. I was just speculating based on his thoughts above which are intriguing.

On the other hand, (speaking of primitive times) while an increasing content of omega 6 in the food supply would signal impending winter and a need to fatten up, there is no lack of other signals that the seasons are changing.

Steven, Meighen, Anna,

Fiberwise – I find Peter’s various takes on fiber, fruit and vegetables very interesting.

Philip Thackray

Robert Andrew Brown said...


There is a certain amount of evidence (but it is sparse and diffuse) to support a link between obesity and Omega 6, and Omega 6 and hibernation.

Robert Brown

Author Omega Six The Devils Fat

Meighen said...

Re fiber, I quote from the video/transcript:

"And, by the way, I am not against natural fiber in fresh fruits and veggies. In moderation, it is perfectly acceptable for healthy, normal weight children and adults. Again, the key words are: healthy, normal weight, and moderation."

So, I don't see much, if any, disagreement between him and the readers here.

As I understand it, the point he's trying to make is that too much fiber, and especially grain fiber, is a problem for a lot of people; I was one of them.


Stephan Guyenet said...


Thanks for pointing that out. So you've had good results from reducing fiber in your diet?

I've actually been sitting on a couple of intervention studies suggesting that wheat bran causes insulin resistance. I haven't posted them because one study is small and the result in the other was not statistically significant (it was a strong trend). If I get sufficient believable data along those lines, I'll put up a post about it. It seems to be a long-term effect, requiring about 2 months to show. So it's invisible to most of these short-term studies that conclude fiber is healthy because it slows glucose absorption.

Stephan Guyenet said...

Oh yeah, and I have another showing that a high-carb diet composed mostly of wheat and sugar skyrockets leptin compared to a high-fat diet. So there is potentially a link between long-term consumption of wheat and insulin/leptin resistance.

AngloAmerikan said...

The body compensates for the calories burned during exercise by a phenomenon known as "hunger".

While it seems logical I haven't noticed it, rather the opposite and I wonder if others have the same experience. I've found exercise to be appetite suppressing. Doing three hundred crunches or sprinting so fast you feel like throwing up do wonders for controlling appetite.
I also wonder if appetite is more psychological than a physical craving. Someone who exercises somewhat obsessionally also finds that the obsession effectively regulates appetite.

Meighen said...

Hi Stephan

Yes, definitely an improvement in the misery level. I'm still trying to fine-tune it (I have low thyroid), eating lower carb, including some sprouted-grain bread. However, the lowest-carb fruit, berries, recommended for those with insulin resistance, are also high fiber. Low-carb chocolate - more fiber. I find it difficult to stay under 10g/day and still have some variety - closer to 15g.


Anna said...

"So, I don't see much, if any, disagreement between him and the readers here.

As I understand it, the point he's trying to make is that too much fiber, and especially grain fiber, is a problem for a lot of people; I was one of them"

Meighen, you're right, not much disagreement here. I also do much better without grain fiber (I found out the hard way that too much grain bran exacerbates/complicates a pelvic prolapse condition). I just don't think the FM book is the best presentation of the fiber issues, though I'll admit, there are very few people out there even questioning the fiber advice, let alone arguing against it.

Like you, I am hypothyroid also. Always needing to fine-tune something ... or figure out how to stay well, despite my doctors.

Stephan Guyenet said...


Interesting. You don't even experience increased hunger in the long term? When I work out, I don't want to see food for about 30 minutes, then I eat everything in sight. There's no doubt that exercise makes me eat more. Weights make me crave protein, endurance exercise makes me crave carbohydrate.

Peter said...

Stephan and AA,

Certainly exercise makes me hungry later in the day too, not immediately, more like 3-4 hours later. I'm never quite sure how much is psychological. I certainly am aware that I have exercised, so should be hungry.....

As an aside I'm not totally anti fiber, unless it's grain derived. I never much check but 7-10g/d from real foods seems quite normal and I think you would need a very damaged digestive system not to tolerate this sort of amount from the occasional berry or vegetable.


Anonymous said...

Robert: "There is a certain amount of evidence (but it is sparse and diffuse) to support a link between obesity and Omega 6, and Omega 6 and hibernation."

How do you explain Herman Taller's "Calories Don't Count" Diet? He had people eat 5 oz a day of safflower oil, corn oil, and margarine, with the rest meat, eggs, fish, butter, cheese, and nuts. He eliminated all carbohydrates including vegetables. People lost weight fast. Also, the people who blame fructose will have to explain Wai Genriiu's diet (Wai Says website). She eats mainly raw fruit, small amounts of raw fish, raw egg yolks, raw nuts shelled by hand, and extra virgin olive oil. She's a model, very thin, no acne, no cellulite, etc. So, maybe the real problem is combining omega-6 oils with a high-carb diet and/or cooked and processed sugars (like sucrose and corn syrup).

Anonymous said...

I have eliminated fiber 100%, and I feel better than ever. I found that fruit fibers (even organic berries) made my eyes blur and cross briefly while I have no reactions to eating strained fruit juice and "unheated" honey. 85% chocolate is too high in fiber IMO. It has 5 times more than potatoes by weight. I eliminted it from my diet for several monhts and tried adding it - I noticed that it caused mild increase in hunger and reduction of energy, and I've never eaten it since then. It's just one more addiction I don't need.

Also, whole grains are far too high in fiber. I feel better with yeast free white sourdough, but I stopped eating it because the company that made it discontinued it. My diet is basically zero fiber, but not zero carb, probably 15-20% carbs. There is no reason to think that you need fiber. My bowels function perfectly without any fiber in my diet. Fact is, they function better.

Fiber is a toxi anti-nutrient which nobody needs to eat. All the claims for its health benefits are fiction and I would suggest that a no-fiber diet is the optimal diet.

Stephan Guyenet said...


I agree that fiber is not a necessary part of a healthy diet. I also think the great majority of people can tolerate average amounts of non-grain fiber without any problems.

Anonymous said...

People can tolerate safflower oil, corn oil, and margarine. In the absence of carbs, they might even lose weight and improve many health markers. It's a question whether it is optimal. If there's no need for fiber, why eat it? With the studies showing that it causes disease, in Peter's high-fat blog and the Fiber Menace book, why take such a risk?

Peter wrote dozens of posts talking about how bad fiber is, how harmful fruits and vegetables are, and how the only reason epi studies find a benefit for them is because people eating more fruits and veggies are more wealthy. Then he chooses after all that to eat fibrous foods (like chocolate and tomatoes and berries) and says that it's "not practical" to eat a no-fiber diet. If all his research is saying that no-fiber is the best approach, why wouldn't it be practical to implement?

mtflight said...


I was wondering what your take on sodium is? My understanding is that insulin causes the kidneys to retain more sodium, so anything that causes insulin resistance is bad for blood pressure--as in metabolic syndrome. Gary Taubes wrote a paper on this.

With hypertension as a risk factor for heart disease, this falls into the carbohydrate hypothesis.

I wonder how many factors are actually involved. keep up the awesome blog.


Stephan Guyenet said...


I doubt that salt is a major player in health. However, I'm also suspicious of it on principle because we eat an amount of it today that would rarely if ever have been found among HGs or subsistence agriculturalists. It could be one factor. There are specific breeds of rats that don't do well on high-salt diet so it can be a stressor under certain circumstances. Then again, controlled trials haven't really supported salt reduction for health as far as I know.