Does Exercise Really Promote Weight Loss?

There’s an old joke lumberjacks still love to tell:

“Why did the train stop?”

Answer: “To let the lumberjack off.”

This quip was coined around the same time that a famous study was conducted. It was a study that measured the caloric intake of lumberjacks, whose appetites are about as notorious as the size of their logs.

It turns out that the caloric intake of a lumberjack is, on average, about 5,000 calories per day.

By comparison, this same study measured the caloric intake of tailors. Tailors, it turns out, consume on average half that: 2,500 calories per day.

It was found in addition that those who change their occupation from light to heavy work, or vice-versa, develop corresponding changes in appetite.

All of which is by way of saying that physical activity makes you hungry. Not exactly news, and yet if it’s followed to its conclusion, the ramifications run deep.

The relationship between weight loss and exercise is a complex relationship, and no matter what anyone tells you, it is not well-understood.

Furthermore, despite prevailing wisdom, despite what you’ve been hammered with all your life, there’s not a shred of real evidence that suggests exercise promotes significant weight loss. As a matter of fact, at one time not so very long ago — up until 1962, to be precise — the medical prescription for obesity was bed rest.

An obesity and diabetes specialist named Russell Wilder, of the Mayo Clinic, lectured famously in 1932 on obesity. Among other things, Mr. Wilder told us that his “fat patients lost more weight with bed rest,” while “unusually strenuous physical exercise slows the rate of weight loss” (Russell Wilder, 1932).

As Wilder and his colleagues reckoned it, “Light exercise burns an insignificant number of calories — amounts that are undone by comparatively effortless changes in diet.”

A University of Michigan researcher named Louis Newburgh calculated, in 1942, that the average man “expends only three calories climbing a flight of stairs. He will have to climb 20 flights of stairs to rid himself of the energy contained in one slice of bread.”

Why then, ask some, don’t we simply skip the stairs and skip the bread? It’s a good question.

These physicians argued that the more taxing the physical activity, the more that the appetite increases. And study after study, beginning with those conducted on our previously mentioned lumberjacks and tailors, confirm this.

“Vigorous muscle exercise usually results in immediate demand for a large meal,” said Hugo Rony (not to be confused with Rice-a-Roni, the San Francisco treat), in a 1940 textbook titled Obesity and Leanness. “Consistently high or low energy expenditures result in consistently high or low levels of appetite. Thus men doing heavy physical work spontaneously eat more than men engaged in sedentary occupations.”

Mr. Rony here goes on to speak of our flapjack-eating lumberjacks, and ends, curiously enough, by asking the same question these men repeatedly asked him:

“Why did the train stop?”

Of course, the real question is not why the train did or didn’t stop, but why we’ve come to believe — and believe so overwhelmingly — the exact opposite of what was once the prevailing medical view?

Credit for that belongs to one Jean Mayer, initially of Harvard University, who then went on to become America’s most influential nutritionist.

As an authority on human-weight regulation, Mayer was among the very first of a new breed, a type that has since come to dominate the field. His predecessors — Wilder, Rony, Newburgh and others — had all been physicians who worked closely with obese and overweight patients. Mayer was not. His training was in physiological chemistry; he had obtained a doctorate at Yale with a dissertation on the interrelationship of vitamins A and C in rats. In the ensuing decades, he would publish hundreds of papers on different aspects of nutrition, including why we get fat, but he never had to reduce obese patients as part of his clinical obligation, and so his hypotheses were less fettered by anecdotal or real-life experience.

As early as 1953, after just a few years of research on laboratory mice, Mayer began extolling the virtues of exercise for weight control. By 1959, the New York Times was crediting him with having “debunked the popular theories” that exercise played little role in weight control. Mayer knew the obese often eat no more than the lean and occasionally even less. This seemed to exclude gluttony as a cause of their weight gain, which meant that these fat people had to be less physically active. Otherwise, how could they take in more calories than they expend and so become fat?

Through the sixties, Mayer documented the relationship between inactivity and the overweight. He noted that fat high-school girls ate “several hundred calories less” than lean classmates. “The laws of thermodynamics were, however, not flouted by this finding,” he wrote, because the obese girls expended less energy than the lean. They were much less active; they spent four times as many hours watching television. Mayer also studied infants. “The striking phenomenon is that the fatter babies were quiet, placid babies that had moderate intake,” Mayer reported, “whereas the babies who had the highest intake tended to be very thin babies, cried a lot, moved a lot, and became very tense.” Thus, Mayer concluded, “some individuals are born very quiet, inactive, and placid and with moderate intake get fat, and some individuals from the very beginning are very active and do not get particularly fat even with high intakes” (Gary Taubes, “We Can’t Work it Out”).

Jean Mayer pioneered the exercise and weight-loss practices that many people today consider axiomatic.

Jean Mayer cited “sedentary living” as the “most important factor” in obesity, and, for that matter, all other adverse health conditions appertaining thereunto.

“Modern people,” said Mayer, “are inert compared with their ancestors [who were] constantly engaged in hard physical labor…. The development of obesity is to a large extent the result of the lack of foresight of a civilisation [sic] which spends billions annually on cars, but is unwilling to include a swimming pool and tennis courts in the plans of every school” (Jean Mayer, 1968).

At that time, many doctors and nutritionists disagreed with Mayer’s pronouncements; and even now, a number of very reputable scientists still do.

“It is a common observation that many obese persons are lazy, i.e. they show decreased impulse to muscle activity. This may be, in part, an effect that excess weight would have on the activity impulse of any normal person” (Rony, 1941).

But isn’t it equally possible that obesity and physical inactivity are symptoms of the same cause?

And isn’t it obvious that the more physically active we are, the hungrier we get?

Mayer’s voracious attack on hunger completely masked the logical inconsistencies his arguments contain.

He did at one point acknowledge that “exercise could make us hungrier,” but in the same breath added “It wasn’t necessarily the case.”

This was the crux of Mayer’s nutritional philosophy.

He alleged a gap in the relationship between appetite and physical activity.

“If,” said Mayer, “exercise is decreased below a certain point, food intake no longer decreases. In other words, walking 30 minutes a day may be equivalent to four slices of bread, but if you don’t walk the half-hour, you still want to eat the four slices.”

This is untrue. And it’s the fatal flaw in his theory. As the lumberjack-tailor study makes very clear, physical activity has a direct and significant bearing on appetite.

And yet from his faulty premise, Mayer, unaware that he was upending the existing worldview on weight loss, wattled forward.

He based this conclusion on two (and only two) of his own studies from the mid-Fifties. The first purported to demonstrate that laboratory rats exercised for a few hours every day will eat less than rats that don’t exercise at all. But this was never replicated. In more recent experiments, the more rats run the more rats eat; weight remains unchanged. And when rats are retired from these exercise programmes, [sic] they eat more than ever and gain weight with age more rapidly than rats that were allowed to remain sedentary. With hamsters and gerbils, exercise increases body weight and body-fat percentage. So exercising makes these particular rodents fatter, not leaner.

Mayer’s second study was an assessment of the diet, physical activity and weights of workers and merchants at a mill in West Bengal, India. This article is still commonly cited as perhaps the only existing evidence that physical activity and appetite do not necessarily go hand in hand. But it, too, has never been replicated, despite (or perhaps because of) a half-century of improvements in methods of assessing diet and energy expenditure in humans. It helped that Mayer promoted his pro-exercise message with a fervor akin to a moral crusade (Gary Taubes, “We Can’t Work it Out”).

In 1977, coinciding with Mayer’s crusade, the New York Times spoke of the “exercise explosion” that had come about because the conventional wisdom of the sixties that exercise was “bad for you” had been transformed into the “new conventional wisdom — that strenuous exercise is good for you.”

The Washington Post as well estimated that “100 million Americans were partaking in the new fitness revolution” — coincident with the start of the current obesity epidemic.

Still, no matter how many billions believe it, the evidence that exercise promotes weight loss has simply never been produced.

My favorite study of the effect of physical activity on weight loss was published in 1989 by a team of Danish researchers. Over the course of 18 months the Danes trained non-athletes to run a marathon. At the end of this training period, the 18 men in the study had lost an average of 5lb of body fat. As for the nine women subjects, the Danes reported, ‘no change in body composition was observed’. That same year, F Xavier Pi-Sunyer reviewed the studies on exercise and weight, and his conclusion was identical to that of the Finnish review’s 11 years later: ‘Decreases, increases, and no changes in body weight and body composition have been observed,’ Pi-Sunyer reported (Ibid).

Here’s the main thing to realize: the relationship between exercise and diet is a complicated relationship, but the chemistry behind weight loss is not complicated:

To lose weight, you must simply use more calories per day than you take in. That’s it.

All the hype and all the fad diets and all the panaceas in the world won’t change that. Exercise does burn calories (even if it’s not quite as many as people think), but it also dramatically increases appetite. Thus, as often as not, exercise tips the scales in the wrong direction.

That’s the fact, Jack.

16 Comments

  • Dave Cochrane

    February 27, 2010

    “To lose weight, you must simply use more calories per day than you take in. That’s it.”

    Absolutely right.

    If I might offer my personal experience, which others may relate to: I have found increased exercise HAS helped ME to lose weight. Here’s how come: I don’t just eat when I’m hungry. I like eating fatty and sweet foods even when I’m not that hungry (oh I know it’s bad, but I so LIKE them). I do find those treats hard to resist, and all the more so when I’m sat behind a desk all day doing a stressful job.

    Call it ‘comfort eating’ if you like, but the point is, I’m often eating for reasons other than hunger. So by increasing my exercise (e.g. walking home from work every night, for one hour, uphill most of the way, and never taking the lift up to my 4th floor home) I’m more hungry when I get home at night, and yet I’m not eating more than I did before I started increasing activity, because I was already eating like a pig.

    Yes, I COULD “skip the bread and skip the stairs” – I just find it easier to have the bread, and then take the stairs (and the long walk home). ALRIGHT, I’M WEAK, DAMMIT… IT’S A SUBSTITUTE FOR A MOTHER’S LOVE THAT I NEVER KNEW [sobs as reaches for another doughnut – mmmmmmm, doughnuts]. I jest; I’m just a greedy bastard.

    It’s always good to read you challenging the conventional wisdom, Ray.

  • Ray

    February 27, 2010

    My dear Mr. Cochrane, it’s always good to hear about your sobs and your dognuts.

    Thanks for dropping by.

  • Candy

    February 27, 2010

    What do you know about being overweight, you skinny fuck?

  • Ray

    February 27, 2010

    Candy, you’d better be smiling when you say that kind of stuff to me.

  • Dave Cochrane

    February 28, 2010

    Yeah Candy…I…mmmmmmmmmmm caaaaaaandy.

  • Redmond

    February 28, 2010

    So Candy

    Are you fat?

    I will attest to the rightness of Ray’s Advice – A few years ago, I wanted to lose 10 pounds. I simply started eating salads for lunch, and did not change another thing about my life. This from a man who did almost no exercise, save that of removing the cork of a bottle wine on occasion, and long walks on the beach.

    It worked wonders.

    If you find you are struggling with a weight issue, if in fact you believe that it is an issue to have extra fat stores, you should give it a try! I highly recommend it.

    Best regards.

    Redmond

  • BedazzledCrone

    February 28, 2010

    Whew!!!!! I thought for a minute, I’d have to give up my WiiFit! The wisdom of the ages – fewer calories & you lose weight.

  • Ned Ryerson

    February 28, 2010

    Candy, don’t hate the player, hate the game.

  • BedazzledCrone

    March 1, 2010

    and if I hear one more thing about the obesity epidemic, I’m going to scream. Doesn’t anybody know what words mean anymore. Where’s the fat virus? Actually there is this: Fat Virus – (http://www.sciencentral.com/articles/view.php3?article_id=218391190), but, as usual, it is a case of “well, we really don’t know”, and there are “lean” people who have had the virus in the study. Whoop-dee-doo!

    Stop super-sizing, everybody. And yes, Candy, I know what it means to be “overweight”. Been there, done that. Over the years, I’ve learned that, for me, when life is good, the weight goes down, when it sucks, the weight goes up – so what? The bottom line is that it always relates to calorie intake – cut out sugar and it is amazing what happens. It is difficult to be “overweight” in societies that think skinny is better. Try and find some pictures of Marilyn Monroe – she wouldn’t make the cover of anything these days (until she lost about 20 pounds!!) How perceptions change!

    As Dave said, ummmmmmmmmmmm doughnuts!

  • Dave Cochrane

    March 2, 2010

    @ Ned and Redmond: Leave fatty alone.

  • Nick

    March 2, 2010

    >>>Doesn’t anybody know what words mean anymore.<<<

    No, apparently they don't. Please see the second definition below. Also, doesn't anybody know how to use question marks any more?

    Main Entry: epidemic
    Function: noun
    Date: 1757
    1 : an outbreak of epidemic disease
    2 : an outbreak or product of sudden rapid spread, growth, or development

  • Ray

    March 3, 2010

    All right, grammar nazi.

  • BedazzledCrone

    March 3, 2010

    No I didn’t put in the question mark! My apologies! (Is there an emoticon for sarcasm?)

    Neither one of those definitions can, as far as I can see, refer to “fat” being an epidemic. There have always been “fat” people. When did someone decide that there was a “sudden rapid spread, growth or development” of fat people? Who decides what is the weight norm, and why do we take their word for it? The notion of who is fat and who is thin is, for the most part, in the eye of the beholder/media/society. Where is Rubens when you need him? What happened to the “epidemic” of girls who were anorexic, or binging and purging to be thin? The word epidemic has apparently lost its meaning, as far as I can see. It seems to be used every time the powers that be want to scare somebody. Create a new “health epidemic” and keep the people in the health bureaucracies in a job.

    May I point out that the definition #1 contains the word it is defining. The OED is better. “epidemic, n. Def. #1 a widespread occurrence of an infectious disease in a community at a particular time. Def. #2 a sudden, widespread occurrence of an undesirable phenomenon. adj. of the nature of an epidemic. ORIGIN C17 (as adj.):from Fr. épidémie, via late L. from Gk epidemia (sorry, don’t know where the e with the bar over it is on the keyboard) ‘prevalence of disease’.”

    And this is from someone who has lost 30 pounds in the last 10 months – mostly because I was damned if I was going to buy a whole new wardrobe when my closet was chockfull of wonderful clothes. See previous post – this must mean that life is good.

    With any luck, there aren’t any grammatical errors in the post. Maybe too many commas.

  • Ray

    March 3, 2010

    BedazzledCrone wrote:

    Maybe too many commas.

    My dear, never enough, until my heart stops beating.

  • Nick

    March 3, 2010

    CRONE WROTE: Is there an emoticon for sarcasm?

    No, but there is actual writing talent. It’s only available in limited supply, though.

    CRONE WROTE: Neither one of those definitions can, as far as I can see, refer to “fat” being an epidemic.

    The second one does precisely that. That’s why I posted it.

    CRONE WROTE: There have always been “fat” people.

    True.

    CRONE WROTE: When did someone decide that there was a “sudden rapid spread, growth or development” of fat people?

    Probably when crops started dying in Mississippi because the asses down there got so huge they started blocking out the sun.

    Also, when studies like these started popping up:

    http://www.cdc.gov/obesity/data/trends.html
    http://www.rand.org/pubs/research_briefs/RB9043-1/index1.html

    CRONE WROTE: Who decides what is the weight norm?

    Doctors, typically.

    CRONE WROTE: and why do we take their word for it?

    Because they’re doctors.

    CRONE WROTE: Where is Rubens when you need him?

    He got caught spanking it to a bunch of anorexic chicks.
    http://en.wikipedia.org/wiki/Paul_Reubens#1991_arrest_and_retreat_from_public_eye

    CRONE WROTE: What happened to the “epidemic” of girls who were anorexic, or binging and purging to be thin?

    Reubens scared them away.

    CRONE WROTE: The word epidemic has apparently lost its meaning, as far as I can see.

    Look harder.

    CRONE WROTE: It seems to be used every time the powers that be want to scare somebody. Create a new “health epidemic” and keep the people in the health bureaucracies in a job.

    What’s this? A paranoia epidemic?

    CRONE WROTE: May I point out that the definition #1 contains the word it is defining.

    Only if I may point out that one is an adjective and the other is a noun.

    CRONE WROTE: Def. #2 a sudden, widespread occurrence of an undesirable phenomenon

    That’s basically the same as what I posted.

    CRONE WROTE: adj. of the nature of an epidemic.

    What the fuck? That definition contains the word it’s defining! Charlatan!

    CRONE WROTE: And this is from someone who has lost 30 pounds in the last 10 months.

    Well done.

    CRONE WROTE: With any luck, there aren’t any grammatical errors in the post.

    If luck is all you have, ride it.

    On a side note, I started exercising/working out/lifting weights in November. I’ve lost about five pounds of fat. Trying to put on muscle now. My goal is to be able to kill a man with my bare hands by this June.

  • BedazzledCrone

    March 4, 2010

    NICK WROTE: Probably when crops started dying in Mississippi because the asses down there got so huge they started blocking out the sun. Also, when studies like these started popping up:
    http://www.cdc.gov/obesity/data/trends.html
    http://www.rand.org/pubs/research_briefs/RB9043-1/index1.html

    Here is a good place to start looking at BMI – someone else who questions the issue: “Death by Obesity? Is it all lies? http://www.diet-blog.com/archives/2006/01/03/death_by_obesity_is_it_all_lies.php

    NICK WROTE: “He got caught spanking it to a bunch of anorexic chicks. http://en.wikipedia.org/wiki/Paul_Reubens#1991_arrest_and_retreat_from_public_eye

    No – that’s Paul REUBANS – I meant Peter Paul Rubens http://en.wikipedia.org/wiki/Peter_Paul_Rubens

    NICK WROTE: “Only if I may point out that one is an adjective and the other is a noun.”

    Obviously, you didn’t get the same education that I did. When I went to public school (grant you, it was a long time ago), you couldn’t use the same word to define a word – that’s just common sense. That first definition tells the reader absolutely nothing – unless they already know what epidemic means. If they did, why would they need to look it up in a dictionary.

    NICK WROTE: What the fuck? That definition contains the word it’s defining! Charlatan!

    Sorry, but that comes at the end of the definition of epidemic. It is all in the same citation. Therefore, it is only explaining the word as an adjective.

    NICK WROTE: CRONE WROTE: Who decides what is the weight norm? Doctors, typically. CRONE WROTE: and why do we take their word for it? Because they’re doctors.

    And, I suppose that doctors have never been known to make mistakes. If this is the case, why do they carry such heavy malpractice insurance? Doctors are subject to the same pressures from the media, from peer pressure, etc., that everyone else is subject to.

    I have nothing against the preventative health movement. What I object to is the stigmatizing and “othering” of people because of their body image. I see too many of my students miserable because of this obsession with body image – both males and females. Few of them have the self-confidence needed to actually believe that they are valuable human beings no matter what their weight is. If they are overweight, they are made to feel that they have some kind of moral failing. They go through dangerous stomach stapling surgeries, just to meet some BMI criteria. I am not saying that if someone is really overweight, that there won’t be health problems for them. However, there is such big money in the “epidemic of fat”, that one has to be a little suspicious of what is driving it. Can you tell me when this obsession with “fat” began? Why do people have to feel guilty about their body image?

    This is so much fun!!!!! Bring it on!

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