Wednesday, January 12, 2011

Exercise ≠ Weight Loss, but It Has Benefits

Fretting about the “obesity epidemic” and the sedentary lifestyle pandemic is one of our national pastimes.  Conventional wisdom tells us that more physical exercise will help us shed unwanted pounds.  ‘Everyone’ knows this.  Academicians, industry representatives, media pundits, and politicians continually harangue us about our inactivity and excess weight, noting the obvious connection between the two.

There’s only one problem with this common knowledge.  It is largely incorrect.  (Consider the information presented in this Time article.  It is important to note that some — especially in the fitness industry — take exception with some of the article’s assertions.)

More studies than anyone can count hit on the weight-exercise link from various angles.  A review of scientific data reveals surprisingly little evidence that weight reduction can be achieved through more exercise.  In fact, experts have known for years that exercise can actually increase weight if it results in building muscle.

We have been told for years that weight is a simple function of the difference between calories expended and calories consumed.  Therefore, it seems obvious that the key to weight loss is either going on a diet or increasing calories burned through exercise — preferably both.  The trouble is that physical exercise burns relatively few additional calories.

Burning calories is harder than you think
It is true that a vigorous session on my Nordic Track cross country ski exerciser burns about triple the calories I burn while sleeping, but this is only a difference of about four calories per minute.  A 30-minute session would burn 120 more calories than complete rest during that time.  A single slice of multi-grain bread with a low-calorie topping would completely eliminate the benefit of the extra calories burned.

Please note that you’d have to burn an extra 3,500 calories to lose a single pound of fat.  You could do that with a high intensity workout on the Nordic Track or running hard — for 14.6 hours straight, that is.  A few fitness extremists might do these kinds of workouts, but most of us have real lives to live.

Exercise is also just one factor affecting a rather complex biological-psychological system.  Researchers have discovered that we tend to eat according to appetite.  In general, this is a good thing.  Hunger is a signal telling us that our bodies need more fuel to properly function.

It turns out that our hunger mechanism almost universally gets us to eat more to compensate for additional exertion.  We used to call this working up an appetite.  It is how our systems were designed to function.  Researchers have also found that people that deliberately exercise often ‘reward’ themselves by eating even more calories than they burned during their workout.

Another interesting set of studies has found that purposeful physical exercise does not lead to overall increased activity.  Whenever we engage in physical exertion, we tend to compensate by reducing physical activity during other parts of the day.  We tend to achieve roughly the same amount and intensity of physical exertion during a 24-hour period regardless of whether we go to the gym, go to work, or do chores around the house.

The upshot is that increased physical exercise does not necessarily translate to weight loss.  At best, it contributes to weight control far less than is commonly believed.

So, should we eat less instead?
If it is so difficult to effectively increase the difference between calorie intake and calories burned by increasing physical activity, what about reducing caloric intake?

A couple of months ago, the news that a nutrition professor lost 27 lbs in 10 weeks by eating mostly Twinkies and junk food took the nation by storm (see CNN article).

The good professor explained that his secret was taking in fewer than 1,800 calories per day, while a maintenance diet for a man his size would be 2,600 calories.  All of the professor’s health markers improved, despite the deplorable quality of the food he ate.  It turned out that food quality was far less important than the number of calories consumed.

But no one can effectively eat fewer calories than they burn for very long.  Once again, this is due to the amazingly adaptable human machine.  Researchers have found that once you go for more than 72 hours taking in fewer calories than you expend, your body begins to compensate by reducing its metabolic rate — the rate at which it burns calories at rest.

When restricting calories eaten, your body works to quickly adapt calorie expenditure to the new reduced intake level.  The rate at which you adapt depends on the amount of excess pounds you are carrying and how much you are eating in relation to actual survival needs.

This is why most dieters see a higher level of weight loss in the first few weeks, followed by decreasing results until they finally hit a plateau where they can’t lose any more, regardless of how hungry they are.  In the meantime, dieters often report hunger, crankiness, and tiredness.  The most common pattern is that they then go off their diet and return to their previous caloric intake, but with their body burning at a reduced rate.  They end up putting on pounds until they weigh more than when they started their diet.

The individualized approach
No single diet has been found to be effective for everyone that needs to lose weight.  But there are a broad variety of dietary approaches that have proved effective for some people.  One of the biggest problems with most diets is that they become psychologically unsatisfying over time, making it difficult to endure.  Some stick it out for years, but most people don’t.

About 23 years ago, I successfully dropped 60 lbs by following The Neuropsychology of Weight Control.  Having always been a bit chubby since childhood, it felt good to be ‘normal’ weight.  A few years later, after adding back 10 lbs, I was able to drop that weight by shifting to the Zone diet.

I later followed the Body for Life plan and later the Burn the Fat, Feed the Muscle approach.  Each of these produced some positive results, but I was always looking for something else.  Last year, after having slowly gained 10 very stubborn lbs, I dropped 13 lbs by following the 6-Week Cure plan.  This approach was perhaps the tastiest of all that I have tried.  It was also easier to eat out on this plan.

A couple of years ago, a friend decided that he was tired being overweight.  He wanted to get back to the weight he was at in his mid-20s.  That represented more than a 70-lb challenge.  After looking at a variety of approaches, he designed his own.  He doesn’t restrict food types (except for dessert items), but he carefully controls portions, eating only a single reasonable portion of foods in a balanced meal three times daily.  His portions are close to the way they are defined by the USDA, not what you see in a restaurant.  He does not eat between meals and he never eats dessert items, candy, or treats.

My friend says that he has been pretty much continuously hungry for more than two years now.  But he did lose the excess weight and can wear clothes that he used to wear years ago.  Although he looks frail and old to some people, he feels more vital than he has felt in years.  He boasts that he recently hiked to Angel’s Landing — a very serious hike — without breaking a sweat.  I doubt I could stick with a diet that left me continually hungry.

A local woman lost 56 lbs over the space of the year to return to normal weight.  She didn’t change her physical activity level.  The only thing she changed in her diet was that she quit drinking soda pop (both regular and diet) and drank water instead.

What I am saying is that it may take some serious work and even trial and error to find a dietary program that works for you both physically and psychologically.  When it comes to diets, one size does not fit all.  Yet there’s nobody that can say for sure what will work for you — except you.

So, what role does exercise play?
If most weight is lost through diet and weight is not significantly affected by exercise, why should anyone exercise?

The simple answer is that there’s more to health and fitness than weight.  I have had a serious daily workout program for about 23 years now.  That program has evolved over time, going from only aerobic workouts to multi-faceted strength and cardio training.  My workouts are not mindless.  They require serious mental focus, which I believe improves brain function.

I have Multiple Sclerosis.  I have no solid evidence that my exercise program has positively affected the disease progression, but I believe it has.  I am in pretty good shape.  Since muscle dysfunction is a common feature of MS, I figure that anything I can do to maintain good muscle tone will likely help counteract, reduce the severity of, and/or somewhat compensate for any such dysfunction I might experience.

Just being in relatively good shape provides valuable psychological benefits.  Moreover, it enables me to serve others when physical work is required.  While weight control is also an important part of this, muscle capacity plays an important role as well.  Given the history of heart disease among older members of my family, I hope to maintain the best cardiovascular health I can as the years go by.

Most (not all) people could benefit in some way from undertaking a more disciplined approach to their physical health, regardless of their age and current health condition.  I think that more of us would do so if we did not have systems in place that subsidize poor health choices.

But I am not so foolish as to believe that we will ever be successful in motivating most to undertake serious health improvement efforts, either by coercion or invitation.  Human nature dictates otherwise.  (Even thinking about forced exercise conjures up the creepy scene in Orwell’s novel 1984 where Winston is working out under surveillance in front of the telescreen in his apartment.)  Since individual health approaches require time and work, they necessarily limit other activities.  Many will judge other activities to be of more personal value to them than the hard work of diet and exercise.

The hardest part of liberty is allowing others to choose alternatives to what we think is best for them, believing that the overall benefits of human freedom outweigh what might be lost through what looks like inferior behavior to us.

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