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Archive for the ‘Exercise’ Category

Exercise affects Satiety

Posted by tinako on March 15, 2013

This connection took me completely by surprise.  I have been asking friends and family how they experience satiety, the sense that you’ve had enough to eat, and found there was a wide variation.  One friend says she has never felt satiety, that she always wants more.  A family member tells me that to him satiety is on or off, and that it doesn’t kick in for a while after eating.  My son and I, on the other hand, feel it slowly coming on as we eat – we feel a stretching sensation in our stomachs and know from experience at what point we need to stop or we will feel ill later.  Is the knowing satiety, or is it the ability to stop eating?  There was a time (before I ran) when I would eat myself sick and continue to eat – did I experience satiety or just a stomachache?

I also figured satiety was something people were ignoring, or the call for food was overpowering will. My friends and family are often surprised that food just doesn’t have much of a hold on me.  For this reason I’m rather humble about my ability to maintain my weight – somehow my wiring has made it easy.

A recent article in the New York Times has astonished me.  In The Appetite Workout, two studies are cited opening a window onto a new view of satiety, and it’s all about exercise-induced hormones.  The article is short and well-written, so I won’t summarize it.

But they weren’t measuring people’s sense of how full they were.  They were measuring how much they ate.  In this case, at least, satiety is not the awareness but the action.

By the way, I run, but my son doesn’t, and we’re both normal weight, but at 13 he still has less control over what he eats than I do, since I shop and he is penniless.

Posted in Exercise, Nutrition | Tagged: , , , , , | 1 Comment »

Debunking the Hunter-Gatherer Workout

Posted by tinako on September 21, 2012

I read an interesting article in the N.Y. Times recently, “Debunking the Hunter-Gatherer Workout.”  Pontzer, the researcher, measured the energy output of one of the last remaining tribes of hunter-gatherers, in order to see if it’s true that modern societies are becoming obese because we are more sedentary.  He found that while they walk much more than the rest of us do, their energy output is not higher because their bodies compensate by becoming more efficient.

He concludes that diet, not lack of exercise, is what is making us obese.

This reinforces other studies I’ve seen.  Click on the Nutrition-Exercise category to the left to see more like this.

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Obesity and Physical Activity

Posted by tinako on November 8, 2010

Steven N. Blair

I just listened to a Yale Rudd Center podcast interview of Steven Blair, PED.  I just the other day listened to Boyd Swinburn talk about how physical activity does not seem to be the main power behind the obesity epidemic, and while Blair does not seem sure about that, he makes the point that while physical inactivity will probably not help an obese person return to normal weight, it makes a big difference in health.

In his research, subjects’ mortality dropped when they added physical activity, such that the increased mortality associated with obesity disappeared.  Diabetes rates lessened, though not to the level of a person of normal weight.  All of this means that a person who is unable to lower their weight can still be healthier as long as they are physically active.  Great news!

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Obesity: Diet vs. Physical Activity

Posted by tinako on November 8, 2010

Boyd Swinburn

This is the second podcast from the Yale Rudd Center interviewing Dr. Boyd Swinburn.  I’ll get right to it.

Dr. Kelly Brownell says that often people in their field (Public Health) claim that diet and exercise are equally important.  Even those who might disagree are disinclined to step on any toes, nutrition researchers pitted against physical activity researchers.  Brownell asks, is this an important debate?

Swinburn agrees that the debate has taken a long time to get going.  He states he’s a firm believer in physical activity’s importance both in obesity and other health impacts, but that doesn’t mean it’s contributing to the problem (or solution) equally with diet.  Of course this has very important implications for what’s driving the obesity epidemic and what the solutions might be.

Swinburn in his research has asked the question directly: How much of the rise in obesity over the last 30 years can be attributed to intake vs. physical activity?

Obesity took off in the developed countries all around the world, and even in developing countries, at about the same time, the ’70s and ’80s.  This means something at a global level changed quite quickly.  That argues quite strongly against changes in our genes, parenting styles, even in our physical activity environment, which is of course tightly linked to the built environment.  Most of us live in cities, and while cities do evolve, they don’t evolve that quickly or at the same time.  We also haven’t had a global collapse of willpower in the last 30 years [I criticized the book Fat Land which seemed to suggest this].  All these personal attributes don’t seem as though they could drive a sudden global epidemic.

So it has to be global, it has to be able to change quickly, and the obvious answer is the food supply.  Looking back over the last 30 years and thinking of the four Ps of marketing:

  • Product: They have changed drastically quantitatively and qualitatively: more variety, more energy-dense.
  • Promotion: It’s far more sophisticated, with marketing to children being of particular concern.
  • Placement: It’s everywhere.  Thirty years ago, food was in food shops; now it’s in almost any shop.
  • Price: The relative price of junk food has come down over time relative to other foods and to income.

These four Ps make a big push factor to influence our energy intake [as compared to “pull,” where people are demanding something, and which food manufacturers insist is the driving force behind the food environment].  It seems clear that energy intake is driving the obesity epidemic.

Brownell repeats Swinburn’s point: during the period of rapid increase in obesity, there have been profound changes in the food supply, but less in physical activity patterns.  Swinburn agreed; cars and TV have been around for a while, though use has increased.  Video games are new, walking to school  has declined, but they seem relatively small contributors to the overall energy balance; the food world has changed much more.

Brownell asks how we can know how much people are eating, and Swinburn’s answer is that he is quite skeptical of surveys that ask people what they eat (they clearly underestimate and that effect seems to have increased over time).  Therefore Swinburn puts more credence in USDA statistics which look at the food supply and come up with a per-capita usage across all countries.  This data shows that over the last 30 years, the food energy supply has increased dramatically.  People have come up with different equations for trying to estimate what percentage of the obesity epidemic is attributable to this food energy supply increase.  Using different equations, the answer is very similar – more than 100%.  That is, the food energy supply increase is more than enough to explain the obesity epidemic.  I’ll say it again, all of the increase in weight can be accounted for by the increase in food calories.

Swinburn talks about “push factor” again.  He says we like to think that we have free choice, but we are actually highly responsive to the environment.  For example, the commuter environment in Amsterdam is highly conducive to cycling, and most people do.  The environment in Atlanta is highly conducive to driving, and that’s what people do.  The same is true for the food environment.  If there’s a lot of food that’s tasty, that’s advertised, that’s low price, we’re going to eat it.  So the calories are being pushed, and we’re responding by eating them.

This all has enormous implications for prevention.  Physical activity interventions are likely to have very modest impacts – good for other areas of your health, but unlikely to have a big impact on weight.  Swinburn’s a big advocate of physical activity, but we need to reduce our expectations for what we can achieve.

The policies need to focus on the food side, but this is a highly charged issue.  Politicians don’t like to fight with industry, which is why government policies typically fall on the physical activity side – no powerful industry is opposed to it.  In order to successfully address obesity, we will have to address the food.

Posted in Exercise, Nutrition | Tagged: , , , , , | 1 Comment »

Fat Land

Posted by tinako on September 17, 2010

I just read Fat Land, by Greg Critser; its tagline is “How Americans became the fattest people in the world.”

What I liked about this book is that it gave an interesting account of how and why portion sizes in movie theaters and restaurants went up.  Briefly, people will not order two packages of popcorn because it makes them feel like gluttons.  This is a problem for movie theaters, because while movie tickets were not all that profitable, the popcorn and drinks were high-markup items, very cheap items for which people would pay a lot.   They tried two-for-one deals, combos, specials, it didn’t matter; one person would not buy two popcorns.  In hindsight the solution seems obvious, but it was a breakthrough in the 1960s: get people to spend just a little more on larger sizes of popcorn and drinks.  The theater adds pennies of popcorn and charges dimes for it.  Sales increases were astounding, and the idea was reluctantly but successfully carried over to fast food.  Voila. [pp.20-1]

Greg Critser

I also liked a brief explanation of why HFCS is not the same as table sugar, despite industry advertising to the contrary [pp.136-7].  There is also a sobering, no, shocking summary of the things that can happen to diabetic bodies [p.141+].

Other than those concise explanations, I had difficulty with the book.  My problems with it were:

1. The writing was frequently unclear.  I’ve read many books on the subject of food in America, and am not sure I’ve come across one that I had so much trouble understanding.   I can’t point to an example now, but I would reread the section a few times and then scratch my head and move on.  It wasn’t that it was a terribly complicated concept; I just felt it was obtusely communicated.

2. I also found the organization within chapters poor and jumpy.  The ending was abrupt, three short paragraphs referring to Dante’s circles of hell that appeared to be tacked on when he realized he needed to finish the book in the next 60 seconds.

3. There was a chapter on physical education that I simply could not force myself to complete.  I got about three quarters through, but it was just too boring.  Granted, my interest is food, so maybe this is my problem and others would be more excited about the history of gym classes.

4. He has a split personality on who is to blame.  Chapters one and two are about how government and industry have sabotaged our food environment, from trade policies promoting palm oil, to that popcorn and french fry supersizing.  But then chapter three, “World Without Boundaries (Who Let the Calories In)”  lambastes permissive American culture, as though once, earlier in the twentieth century, we were all upright citizens who could control ourselves, and then suddenly, mid-century, people fundamentally changed and were now rampant hedonists.  Well, it could be that at one time homo sapiens was able to control its urges and then, coincidentally, just as business started discovering how to get us to buy more, homo sapiens changed and now were a bunch of losers.  Or, it could be that those pious early humans didn’t have pharmacies that sold potato chips, 20-oz. Coke vending machines in schools, and 610-calorie french fries on every block.  People have always wanted “what they want, when they want it.”  But now someone is shoving it in their faces.

One sentence particularly annoyed me: “Parents must take back control of the table” [p.161].  I don’t think he was talking about me, since I provide a healthy diet to my kids and do my best to shield them from unhealthy outside influences.  But that’s just it!  There are so many ways in which our food environment undermines parental efforts in this respect.  Restaurant kids meals are always horrible, commercials on TV encourage kids to eat unhealthy food, teachers have kids visit web sites from candy companies in school, unhealthy snacks are often given to kids in preschool programs, lollypops are handed out on the way out of restaurants, fast food restaurants line the streets near schools, candy and sugary drinks are sold at gas stations and drug stores on the way home from school, schools have vending machines selling sports drinks and candy, weekly birthday or holiday parties include cupcakes with 4″ of icing, classes that behave well earn pizza or doughnut parties; chips, cookies, ice cream, and Little Debbie snack bars are sold daily in the lunchrooms, and on the first day of school my son’s teacher handed out taffy to kids who raised their hands.  Every one of these situations makes parents’ job, to raise healthy kids, harder.

In his last chapter, “What Can Be Done,” Critser seems to make more sense again; he suggests two successful personal approaches such as weight loss intervention programs for schoolchildren and educating and encouraging children to have less screen time, but most of the ideas are not about personal, unilateral change, but about changing the environment: schools, fat or sugar taxes, playgrounds, and other federal programs.  I think Critser has the right idea; he just forgot about it in chapter three.

I agree with Kelly Brownell that obesity is a failure of personal choice, but also a failure of environment.  Our current environment is undermining our attempts to make good choices.  Blaming individuals, either one-by-one or collectively, is not a helpful strategy.

Posted in Exercise, Nutrition, Schools | Tagged: , , , , , | 4 Comments »

No Wonder We’re Obese – A new way of thinking about the epidemic

Posted by tinako on June 30, 2010

Up until about two weeks ago, I would say that I had the same idea about obesity that most people, including obese people themselves, have.  You’ve heard of the ELFS diet?  “Eat Less Food, Stupid!”  It’s offensive, but I think it about sums up what most people think is the problem: obesity is a personal failure to control oneself.

But in the last two weeks, I have thrown myself into a Psychology course Yale offers free online, and I have been immersed in a new way of thinking about obesity and overweight in general.

I have listened to scientists talking about the animal studies they have conducted indicating that high-fat or high-sugar foods are addicting in a way very similar to cocaine, alcohol and nicotine.  Animals eat normally when exposed to healthy foods but overeat when they are allowed to eat fat and sugar.  Rats exposed to sugar develop tolerance to it which makes them need more of it to get the same dopamine reaction.  Rats will choose sugar over cocaine or alcohol.  Fat and sugar cause changes in the brain scans of obese humans that are indistinguishable from the changes that cocaine cause.  This addiction, like that of other drugs, appears to prime the victim to lifelong cravings for the substance.  There are opioid-blocking drugs, usually used for alcoholics, that work to treat binge eaters [Contrave is a combination of several of them].  As with other addictive substances, habitual ingestion of sugar causes the body to prepare for it when cues are received (sight, smell causes insulin increases, etc.).  When people experience these cues without taking the expected cocaine, alcohol, nicotine, or sugar, they experience strong cravings because their bodies are prepped.  People and animals both need more of the sugar and fat over time to maintain the same levels of dopamine in their brains.  Patients with overeating problems use the language of addiction, “craving,” “loss of control,” and experience visible and measurable withdrawal symptoms, such as change in body temperature.   People continue to overeat despite clear negative consequences physically, socially, and healthwise.  It is not clear whether it is only sugar which is addictive, or whether it could be fat, chemical additives, or other ingredients such as High Fructose Corn Syrup.  All these professionals say that more studies are needed before any of these ingredients are labeled addictive substances, but as you can see, they are well on the way.

If alcohol or cocaine were available everywhere, dumped into school lunches and products aimed at children, advertised all day, and pushed on people constantly, through office candy bowls and birthday celebrations, school parties, miles of fast food joints, and shelves of junk in gas stations and pharmacies, would we be surprised that people had a problem resisting it? Nicotine was once advertised to children, loaded into vending machines, and sold for a quarter a pack, and no one thought anything of it.  When we learned how addictive it was, we put a stop to it.  If it turns out that sugar is addictive, as it appears to be, what ramifications will that have?

I have learned that sugar is jammed into things it has no business in, such as peanut butter, Dinty Moore Beef Stew, and ketchup.  Why?  Because it tastes good and increases sales.  It reminds me of the way Coca-Cola got its start; now it just relies on a HFCS high.

Our bodies’ biology evolved in a world of scarcity, and that biology fights us in a world of overabundance.  We developed very strong tastes for sugar and fat, the hard-to-come-by energy-dense foods that would help us survive through the lean times.  Our bodies are designed to store this energy as body fat, and to conserve it in lean times.  Our bodies don’t care that we are trying the newest diet – it thinks we are facing starvation, and cuts our metabolism and increases our desire for food.

We are often under stress, and stress leads to unhealthful eating.  In the Yerkes primate study, subordinate monkeys (who experience more stress) ate a little less of a healthy diet than dominant monkeys, but when sugar and fat were introduced, dominants ate a bit more but subordinates ate a lot more, especially at night.  The fat and sugar was a comfort to them, an efficient dopamine-stimulating coping strategy.

How about genes?  It is estimated, using twin studies, that 25-40% of population weight variance is due to genetics.  Adopted children’s weights show a strong correlation to their biological parents’ weights, and little to their adopted parents’ weights.

“Genetic influences largely determine whether a person can become obese, but it is the environment that determines whether a person does become obese and the extent of that obesity.” – Stunkard & Meyer 1993

“Genes load the gun and the environment pulls the trigger.” – Bray 1988

You know how some people can eat and eat and never gain a pound?  I’m not totally like that, but I have to admit, I have never had a problem with weight.  But people with the obesity genes would have had great advantages thousands of years ago.  They would have been the ones who could starve and starve and never lose a pound.  That’s what they’re up against when they try to diet.

An economist pointed out that once upon a time work was hard work.  People toiled and sweated.  Some still do that, but many perform more sedentary labor, which means that instead of being paid to spend calories, it has become more expensive, primarily in lost leisure time.  Everyone is busy, but it doesn’t take too much imagination to consider a hard life of stand-in-one-place retail work sandwiched with a bus ride home and caring for children in a difficult neighborhood which does not give an opportunity for an hour of jogging.  This probably isn’t an uncommon situation, and can you blame them for not getting enough exercise?

Whose failure is it that our government’s farm bill subsidizes exactly the crops that go into the worst foods?  Corn and soy are converted into animal flesh and most of the unidentifiable chemicals that populate processed food ingredient lists.  The resulting artificial cheapness of  these foods explains why they are so profitable, so heavily advertised, and so prevalent.  How many times have you wondered why vegetables are so expensive?  It’s the other way around – American spend less per capita on food than any other nation.  Vegetables, even organic ones, probably are a truer reflection of the actual cost of food, and they don’t seem expensive until you compare them with our dirt-cheap processed food and 99 cent menu items.  Our laws encourage consumption of food that will make people sick.  The Physician’s Committee for Responsible Medicine makes the connection between this issue and our hair-tearing about the high costs of medical care:

“Even if the steak and cheese produced on American farms foster health problems, our government rallies behind agribusiness all the way to the emergency room.  Sadly, every administration in recent decades has been caught up in a system that not only tolerates ill health, but encourages it.” – Barnard

“A good source of 7 vitamins and minerals”

Food manufacturers have most of us outsmarted.  They deliberately tweak their marketing and the product itself to trick us into eating more than we think we are.  They sneak in unhealthy fat and sugar, they cause us to increase our portion sizes by making the product more nonuniform (studies show people will eat more of a snack mix than a homogeneous snack such as plain pretzels), they put health claims on packages that are usually inversely related to the healthfulness of the product within (compare health claims on packages of Cocoa Puffs “now with Whole Grains” to a package of carrots), they trumpet the vitamins they added to Pop-Tarts, for Pete’s sake.  Vitamin deficiencies are not really a problem for most Americans – Pop-Tarts are the problem!  Restaurants know that we think a good deal is more food for the same price, and so we come back to establishments that load up our plates, so now they all do, and it is now very difficult to have restraint when we eat out – our whole sense of how much is reasonable to eat has been sideswiped.  Industries study us and tweak their approach to push our buttons.  We don’t stand a chance.

Diets don’t work.  How many obese people do you know who followed a diet, took off weight, and kept it off for five years?  When diet promoters give statistics of success for their products, they tout how fast the weight comes off and usually use a six-month standard, but that isn’t good enough.  Here is a study that followed several diet and exercise combinations for two years, and at the end of that period there was little net weight loss and two of the three groups ended up heavier.  The best-rated diet, Weight Watchers, repeatedly says you will keep weight off “if you stick to it.”  That’s the whole point.  People with with a chronic addiction to unhealthy foods, immersed in a toxic environment of cheap, tasty, ubiquitous, artificial foodlike substances, are unlikely to be able to resist for long.

Click to zoom in on this amazing picture.

Look at the food in the grocery store.  If you did an item-by-item analysis, I think you would find that the vast majority of it is crud that no one should be eating.  What are the percentages of white pasta to whole wheat?  How about for bread products?  What is the proportion of truly healthful cereals to the rest?  How many of those peanut butters and jellies are the best they could be?  How many aisles are dedicated to snacks and sodas? Compare the number of bags of white flour to whole wheat.  White rice to brown.  Juices with sugar to juices without.  There’s a little tiny shelf dedicated to dry beans, and an entire aisle of freezers dedicated to processed meals, fried whatever, and desserts.  Half an aisle honors ice cream.  There is more space dedicated to candy than to canned vegetables.  Remember the food pyramid?  How is all that candy going to cram into that teeny tiny little triangle at the top??

I was talking about this toxic environment with my Dad and he said he wondered why he overate the stuff he bought, and then started wondering why he bought what he did at all, and the answer was, it was there.  He would wander down an aisle and, oh, that looks good, and here it is in the store, people must eat this, so why shouldn’t I?

Now, you can very reasonably counter that the stuff is there in those proportions because that’s what people demand.  That may take the blame off the store, but how does it help the person who’s trying to lose weight?  Having one person go on a diet in the midst of this feeding frenzy is like putting one of your fingers on a diet.  How can we blame individuals for this collective and often state-sponsored mess?

Yes, people can make better choices, but the deck is vastly stacked against us: a biology designed for scarcity, a food economy which separates food as a commercial commodity from food as nutrition and encourages consumption of unhealthy foods, nutrition education that is designed not by health advocates but by industry interests, and food manufacturers whose object is to manipulate us into eating more and more of food that’s worse and worse for us.

In these studies, in the articles I have read, the doctors, lawyers, economists, psychologists,and researchers I have heard speak in their own words, I have found a new compassion for and understanding of the problem of obesity, which may even surpass what obese people feel about themselves.  They think it’s all their fault, too.

One thing that all these professionals seem to have in common is that they do not know what to do about the problem.  The answer doesn’t seem to be diets, litigation (suing manufacturers), or even education.  How well has blaming or shaming the obese worked?  Maybe we should abandon that tactic.  A vaccine was mentioned as a possibility, something I would have scoffed at two weeks ago as a pharmacological solution for a lifestyle problem.  Now I’m not so sure.  Prevention of this chronic disease was discussed, particularly in light of all the marketing towards children.  Sugar taxes are unpopular with the public because they don’t want anyone telling them what to eat.  If you think there aren’t people all day telling you what to eat, through ads, your tax dollars, the USDA in your child’s classroom, and on and on, you haven’t been paying attention.  Wouldn’t you prefer it to be someone who cares about your health?

I’m coming to the conclusion that a huge part of the problem is the farm bill, a result of our senate system being skewed for more representation for less populated (farming) states.  I’m not opposed to farmers and I have no informed opinion on farm subsidies in general, but it doesn’t seem to make much sense to subsidize unhealthy food and then wonder why our health is so poor.  But no one can be sure.  Some of those professionals I heard felt that a variety of societal approaches should be tried to determine what works, and this is happening now, but in a haphazard, segmented way.   One suggestion was that a governmental department for food health be created, basically breaking that task away from the catastrophically conflicted USDA, which is primarily charged with promoting agriculture.  There’s no H or N for health or nutrition in “USDA.”

I’ve tried to present here an overview of thinking about obesity in a new way.  If this topic interests you, I would urge you to find out more through the Yale course linked above and through the Yale Rudd Center.

Posted in Exercise, Musings, Nutrition | Tagged: , , , , , | 1 Comment »