The Role of Exercise in Weight Loss


Want to lose weight?  The tried and true advice has always been “Exercise and eat right.”  Hard to argue with that.  Burn calories via exercise and eat less and/or eat better quality food.  Done and done.  Recently however, the role of exercise in this process has been questioned.  Time magazine went so far as to tell us Why Exercise Won’t Make You ThinOther research has suggested that the eating part of the equation is more powerful than the exercise part.  Further, from experience as a personal trainer, I’ve seen many a gym member tell themselves “Hey, I’m exercising.  I can eat whatever I want!”  I have yet to see anyone succeed following that route.  So what if any role does exercise play in shaping our physique?

The New York Times has weighed in with a very interesting, nuanced and informative article on the topic.  Weighing the Evidence on Exercise tells us among other things that exercise alone may not make you lean, but that it will likely help keep you thin if and when you get there.  Further, it seems exercise has a different effect on the appetites of men vs. women.

“When you look at the results in the National Weight Control Registry,” Harvard researcher Barry Braun says, “you see over and over that exercise is one constant among people who’ve maintained their weight loss.”

The article cites two studies to this effect  One by the American College of Sports Medicine demonstrated that appetite was blunted in men who ran on a treadmill for 1.5 hrs.  In another study by Harvard researchers reported in the American Journal of Physiology, men and women walked on treadmills and their appetites were monitored.  The men showed similar results to the ACSM study.  The women however showed increased appetite.  It seems that female physiology is very favorably given over to storing energy (as fat–eeeeeeech!!!)

The Harvard study found other very valuable information which I’ll get to in a moment but first, more about who was studied.  The weight-change history of 34,000 women was tracked for 13 years.  (The large sample size and length of the study are two strengths.)  The average age of the women at the start of the study was 54 years.  Now the important information as reported by the Times:

“During that time, the women gained, on average, six pounds. Some packed on considerably more. But a small subset gained far less, coming close to maintaining the body size with which they started the study. Those were the women who reported exercising almost every day for an hour or so. (emphasis is mine) The exercise involved was not strenuous.”

Finally, the Times article discusses a study from the University of Colorado.  In this study, rats were fattened and allowed to be sedentary for a time.  The rats’ diets were then switched to low-calorie fare and half of them were made to run on treadmills for about 30 minutes a day.  (Strangely, Jillian Michaels was not involved.)  The results of the study as reported by the Times are as follows:

“Then the fun began. For the final eight weeks of the experiment, the rats were allowed to relapse, to eat as much food as they wanted. The rats that had not been running on the treadmill fell upon the food eagerly. Most regained the weight they lost and then some.”

But the exercising rats metabolized calories differently. They tended to burn fat immediately after their meals, while the sedentary rats’ bodies preferentially burned carbohydrates and sent the fat off to be stored in fat cells. The running rats’ bodies, meanwhile, also produced signals suggesting that they were satiated and didn’t need more kibble. Although the treadmill exercisers regained some weight, their relapses were not as extreme. Exercise ‘re-established the homeostatic steady state between intake and expenditure to defend a lower body weight,’ the study authors concluded. Running had remade the rats’ bodies so that they ate less. (emphasis is mine)

To reinforce the message from all this, Science Daily reports on another study not mentioned in the Times article: Diet Alone Will Not Likely Lead to Significant Weight Loss, Study Suggests.  Here,  Oregon Health & Science University studied monkeys that were fed a high-fat diet for several years.  They then were placed on a low-fat diet for a month.  The important information is this:

“Surprisingly, there was no significant weight loss at the end of the month,” explained OHSU post-doctoral fellow Elinor Sullivan, Ph.D. “However, there was a significant change in the activity levels for these monkeys. Naturally occurring levels of physical activity for the animals began to diminish soon after the reduced-calorie diet began. When caloric intake was further reduced in a second month, physical activity in the monkeys diminished even further.”

So what’s the take-home message from all this?  First, as a personal trainer, I find it highly interesting  the actual role that exercise seems to play in weight loss.  It’s not so much a direct influence as it is something that changes our bodies over the long haul, and sets the stage for us to stay trim.  Beyond that, think of this evidence in light of research (here, and here for instance) showing that exercise alone won’t do the trick when it comes to weight loss and we have a very familiar message: To lose weight we must eat right and exercise.

Beating Obesity


The latest edition of the Atlantic features an excellent article on our nation’s struggle with obesity.   Beating Obesity is written by Marc Ambinder and it’s a thoughtful, in-depth look at the political and social ramifications of this seemingly losing battle.  We learn about the major players including First Lady Michelle Obama, the food industry and the insurance companies.  (Ambinder himself struggled with obesity and eventually underwent bariatric surgery as a solution.)  Ambinder does a very good job in discussing the issues of individual responsibility and the environmental challenges we face such as food at every checkout line (not just at the grocery store), ever growing portion sizes, and junk food that is cheaper than fresh fruits and vegetables.

Most importantly he examines the moral and demographic issues of obesity.  He notes the following:

“Black children are more at peril of becoming obese than white children; black women are more than 50 percent more likely to be obese than white women. ‘At the current rate of increase,’ epidemiologists noted in a recent article in Obesity, ‘it will take less than 30 years for all black women to become overweight or obese.’ Obesity rates are above average among Mexican American boys, as they are among Hispanics generally. Obesity rates among young American Indians tend to be nearly twice the national average.

Please check out the article.  It’s an excellent piece.

Compulsive Eating is Similar to Drug Addiction


Obesity-related eating issues are in the news again.  This time new research indicates that the physiological dynamics of overeating are the same as drug addiction.  Compulsive Eating Shares Addictive Biochemical Mechanism With Cocaine, Heroin Abuse, Study Shows comes from Science Daily.  The article summarizes a Scripps Research Institute study that was published recently in the journal Nature Neuroscience.

The study examined the brain chemistry of rats that were fed high-fat, high-sugar diets similar to human junk food.  The rats quickly became obese and at the same time their brain chemistry showed striking changes.  Pleasure centers in their brains changed and became less responsive.  The result was the rats had to eat more and more in order to stimulate these regions.  These dynamics of food addiction mirror those of rats addicted to cocaine and heroin.  Paul J. Kenny, one of the scientists who conducted the study said,

“It presents the most thorough and compelling evidence that drug addiction and obesity are based on the same underlying neurobiological mechanisms. In the study, the animals completely lost control over their eating behavior, the primary hallmark of addiction. They continued to overeat even when they anticipated receiving electric shocks, highlighting just how motivated they were to consume the palatable food.”

A fascinating development in the study came when researchers replaced the junk food with nutritious food: the rats refused to eat.  They starved for nearly two weeks after the change.

What seems to be happening to these rats (and likely to obese humans) is that consumption of highly pleasurable food overstimulates and dulls the reward centers of the brain.  More food (or drugs) are needed to stimulate feelings of reward and pleasure.  Without getting too technical, the neurotransmitter dopamine and it’s receptors in the brain are the key elements here.  Dopamine is released in the brain by pleasurable experiences such as drug or food consumption.  Consume too much of either and the brain is flooded with dopamine which is essentially bad for dopamine receptors.  Over time the brain actually undergoes physical changes and addictive behavior becomes normal and very difficult to change.

The big issue to me is that overeating and obesity are very complex and not at all simple matters of will power.  Personal trainers and nutritionists must realize that the brain function of the obese person is very different from the non-obese person.  Simply instructing someone to eat differently rarely works and now we know very specifically why.

To that point, I’m skeptical of our various efforts to educate the public on the caloric content in our food (first in NYC and most recently on a national level.)  Similarly, it seems that small taxes on soda do little to curb consumption of the sugary junk.  Simply putting the information in front of our eyes or enacting a slight monetary penalty isn’t enough and I don’t believe there are many ways government can affect our food choices.  (I would be curious though to see the effects of eliminating subsidies for corn, wheat and soybeans.  These subsidies keep the price of junk food–which is actually quite complex if you look at the ingredients–artificially low.  So this addictive food is also dirt cheap.  You and I are paying for this with our taxes!)  That said, my hope is that those battling to lose weight won’t give up and resign themselves to poor health by saying “I’m addicted.  There’s nothing I can do.”

From what I’ve seen of successful weight loss seems very similar to what I know of overcoming addiction.  That is, the individual must decide to make a change for him or herself.  Until the individual knowingly makes a firm decision to change no amount of preaching, pushing or cajoling by friends, a spouse, or parents will make the difference.  And it is hard work.   Perhaps now by recognizing the brain chemistry of over eating we can develop more effective strategies to slim down.

More Magical Fitness Nonsense: Part II


The first post of this series looked at a new weight loss pill being developed by General Nutrition Centers.  It’s something containing caffeine, black pepper and an ingredient in hot peppers.  Who knows?  Maybe this thing actually is weight-loss in a pill.  I doubt it though.  Most likely this is just the latest version of fitness snake oil–and there’s plenty more out there.

If you’re any sort of follower of popular culture then you may know of the TV show the Biggest Loser. If so, then you know of Jillian Michaels, one of the show’s trainers.  Michaels was sued in February by a fan of the show.  The woman claims she bought a fat loss supplement sold by Michaels–and guess what!!  It didn’t work.  The suit further claims the product contains a tasty item called citrus aurantium (aka bitter orange).  This substance contains amphetamine compounds which are similar to those found in ephedrine.  These compounds are stimulants and they act to restrict blood vessels and to increase blood pressure and heart rate.  This bitter orange stuff has been used to replace ephedra in many fat-loss products.  Ephedra was linked to the 2003 death of Baltimore Orioles pitcher David Bechler.

More news on this topic came out in January of this year when the Abbott Laboratories’ weight-loss drug sibutramine was cited by European offiicials as being potentially harmful to heart disease patients.  The F. D. A. added a warning to the drug, known as the products Reductil, Meridia and Sibutrex.  (Wow, take a look at the contraindications and side effects of this stuff!  Doesn’t look fun.) 

What other kooky chemicals are in the news?  The article F. D. A. Finds ‘Natural’ Diet Pills Laced With Drugs appeared in the New York Times Business section back in February of 2009.  The story discusses a product called StarCaps.  StarCaps were promoted by celebrities and touted as a “natural” weight loss product that used papaya as an active ingredient.  Seems perhaps the true active ingredient was something called bumetanide, a diuretic that can cause all sorts of ugly side effects.  The article further states:

“In a continuing investigation that has prompted consumer warnings and recalls by some distributors, the F.D.A. has determined that dozens of weight-loss supplements, most of them imported from China, contain hidden and potentially harmful drugs.”

These stories remind me of the Fen-phen episode of several years ago.  Fen-phen was a combination of two weight-loss drugs marketed and sold by Wyeth.  The drug combination was very popular and seemingly effective.  Problem was Fen-phen caused heart conditions such as valvular heart disease, severe hypertension and even death in some users.  The product is no longer available and as of 2005, there were about 50,000 liability cases still to be resolved with an estimated  total of $14 billion in liability.  Seems that we may be eager to repeat history.

So what is the big picture?  Americans want to lose weight and there’s big money in that concept.  We’re not too good at exercising and eating right though.  If weight loss can come in a pill then a lot of us are very likely to spend plenty of cash on the product–nevermind the idea of “too-good-to-be-true” plays prominently in the background.  Thanks to the supplement industry-friendly DSHEA act of 1994  these supplements live in a gray area between food and drugs, and they don’t undergo the same scrutiny.  (Quackwatch gives a good commentary.)  Therefore some supplements may be just as powerful and potentially dangerous to many users as any other prescription drug.  (In fact, the risks posed by these weight-loss formulas may be more dangerous than simply being overweight!)  As in the case of StarCaps, the ingredient label may not tell us everything that’s in a supplement.  These are murky waters for the consumer.

Should these products be banned outright?  I’m not sure.  Can these products be used safely?  Maybe.  Clearly for some people these products are dangerous and possibly deadly.  This stuff must be seen through the same lens as any other medication.  Don’t let a label like “all-natural” fool you (BTW, black widow venom is all-natural too) and don’t let a celebrity face make you a sucker.  A healthy lifestyle has yet to come in a pill and it never will.  Get up, go walk around, and eat something that grew in the ground.

More Magic Fitness Nonsense: Part I


I love this stuff!  From somewhat questionable vitamins, to goofy “health” food, to the out-and-out fantasy Cookie Diet, we continue to search for a way around eating right and exercising.  The latest magic potion to come out of Fantasy Fitness Land is a pill which has been developed by General Nutrition Centers (GNC) and tested by Oklahoma University.  (I’m glad the Sooners took on this strange project instead of the University of Texas.)  You can read all about it at Science Daily in an article titled Weight-loss supplement has potential to burn fair amount of calories

It seems this substance contains three things: black pepper, caffeine, and capsaicin–the stuff that makes hot peppers hot. 

(Now, as it turns out, I actually created this combination some years ago and I’ve been consuming it roughly once a week in the form of a morning meal known as breakfast.  I eat an omlette, sprinkle on some black pepper, splash on some hot sauce, and drink two cups of coffee.  Too bad I didn’t patent the whole process. )

The article is fairly brief and doesn’t give much information but I can forsee this new weight loss pill flying off the shelves into the hands of people who desperately want to lose weight but who refuse to take on the tried-and-true guaranteed methods to healthy weight loss–that is eating right most of the time and working hard often.  I’ll post more information on this type of snake oil.

NEAT and the Benefits of Hunger: Part III


In Part I discussed Non-Exercise Activity Thermogenesis (NEAT).  The biochemistry of hunger and the possible benefits of hunger were the issues in Part II.  I ended by posing the question of whether or not consuming several small meals per day was more or less conducive to losing weight than the popular admonition to eat up to six small meals per day.  It seems the verdict is very much out.  The answer is: It depends…

To start with, here’s an article by registered dietitian Kristine Clark writing for the IDEA Health & Fitness Association.  Clark first offers wise observations on the exact nature of hunger and satiety.  Hunger being the main reason we should eat at all and satiety being the signal to stop.  She writes,

“‘Unfortunately, many people are out of touch with the feeling of satiety.”  Marion Nestle—researcher, author and professor of nutrition at New York University—says, ‘You can’t teach satiety.  People have to learn it themselves.’  The bottom line is that recognition of both hunger and satiety is key to appropriate eating.

Anyone seeking weight loss must take that statement to heart.

Clark then refers to the research from the 1960s and ’70s that associated several small meals with a leaner physique.  I won’t go into the details of the studies (references are found at the end of Clark’s article) but both studies show weaknesses worth considering.  The small sample sizes and the use of a 24-hr diet recall interview in one study make me question to what degree we should hold to the implications of these studies.  I’m not the only one thinking this.  For further reading on the strength or lack thereof of nutritional studies, look here and here.  (And remember these sorts of weaknesses the next time a news anchor tells you that some study shows This causes That. Odds are the cause and effect aren’t that strongly linked.)

Most importantly, Clark interviews Dr. Barbara Rolls of the Penn St. Nutritional Science Department.  Essentially she says that meal frequency isn’t the key issue–It’s how much you eat!

“As long as people hold their calorie intake constant—as long as they eat less than what they normally eat, whether in six or three increments —they will lose weight, regardless of the frequency.”
– Barbara Rolls, PhD

So it should be obvious.  The key issue is energy intake vs. energy expenditure.  This is no revelation.  Whether it’s three, four, five or six meals per day, if we eat too much then we get fat.  (I’ll add my own opinion to this equation and say that the quality and the nature of our food–real food vs. food-like substances–is of tremendous importance to physique goals as well.)

I’m surprised by the fairly weak correlation between the several-small-meals strategy and successful weight loss.  I’ve been saying this to clients as if it were a settled subject.  I will say though I believe the first time I ever heard the suggestion to eat many times throughout the day was as advice to bodybuilders who were trying to gain weight, not lose it.  Bodybuilders need the raw materials to add body mass so loading up on food several times a day is about the only way to do it.  In contrast, the general public doesn’t have that need, and it stands to reason that by many among us may easily eat too much if we’re eating up to six times a day.

No second helping for me, thanks.

No second helping for me, thanks.

Finally, I didn’t know exactly where to put this, but General Stanley McChrystal, the current commander of U.S. forces in Afghanistan, eats one meal per day!  This man is a dedicated runner with a Special Forces background.  One meal per day…