Exercise and Weight Loss: The Conversation Goes On
Posted Apr 20 2010 4:50am
By Barbara Berkeley
For native New Yorkers there is a certain imperative that comes along with the weekend: that would be reading the Sunday “New York Times.” When Don and I moved to Cleveland in 1987, my first question was whether I could get the “Times” delivered. Fool that I was, it seemed to me at the time that I was relocating to a vast wasteland where contact with civilization (read Manhattan) was not guaranteed.
Although we’ve become inveterate Clevelanders (Go Cavs!), certain habits die hard. The “Times” is one of those. So, for the past 23 years, our intrepid delivery guy has been tossing the paper in that perfect spot at the base of the garage door.
My first stop in the Sunday paper is the magazine section. My mother is a crossword fanatic and has always shamed the entire family by completing the Sunday “Times” puzzle with lightening speed. She still does this (and just as fast) at age 91. If you want proof of the brain-enhancing effects of mental gymnastics, look no farther than my Mom. When my sister and I entered our late 20s, we decided that we had better carry on this family tradition. All three of us do the Sunday puzzle, occasionally calling each other for consultations here or there.
This morning’s magazine section, however, diverted me from my intense pursuit of across and down. Today, the “Times” decided to devote its magazine to Wellness. I couldn’t resist dipping into the cornucopia of articles. I soon was scribbling notes all over the pages, a sure sign that I was headed toward a blog post.
You can read all of the Wellness articles in the Magazine by logging onto the “ New York Times” websiteand scrolling down to Magazine. I may write about some of the other topics in future posts, but today I want to focus on the excellent article detailing recent research into exercise and weight loss.
I call this article excellent, of course, because it supports my beliefs on the subject. Where exercise, diet and health are concerned, we should be honest and say that – if we look hard enough – we can find research evidence that supports almost any position. In my case, the beliefs I hold come from what I’ve observed in more than 15 years of working with dieters. Thus, I am thrilled when reasonable science confirms what I’ve seen in practice and I’m suspicious of results that say that something I have never observed clinically is bound to be true.
This is an article that confirms the belief that exercise is weak for weight loss and strong for maintenance. Since I’ve been pilloried on the Internet in the past for saying that exercise doesn’t cause weight loss, I’d like to begin by clarifying my position at bit:
1. I am an exercise fanatic and believe in the vital importance of physical activity. I would advise everyone to exercise, both during weight loss and thereafter. Nevertheless, we need to be realistic about one particular property of exercise. In and of itself, it can’t be relied upon as an effective tool for weight reduction.
2. The potency of exercise as a weight loss aid may have a lot to do with amount. It’s obviously true that someone who is running marathons will lose weight if they don’t compensate with extra calories. But how many of us are marathoners?
3. Who you are may also matter. Youngish men appear to get more loss from exercise than others. The “Times” article had a quote that made me go into fist-pumping mode. “In general,” says Eric Ravussin, a professor at the Pennington Biomedical Research Center in Louisiana and an ‘expert on weight loss’, “exercise by itself is pretty useless for weight loss.” The article sums it up this way: “The newest science suggests that exercise alone will not make you thin, but it may determine whether you stay thin.”
With the understanding that there may be some exceptions to this rule, I couldn’t agree more. I often use a particular slide when I give talks about weight loss. It looks at multiple complete studies which compared weight loss via diet alone with weight loss via a combination of diet and exercise. In nearly every case, the addition of exercise did not cause additional weight loss. In some studies, those who did not exercise did better than those who did. This might reflect a phenomenon that I often see clinically, the tendency to eat more when one is exercising. In some people, this may come simply from the mistaken belief that exercise gives them a free pass. But the “Times” article suggests a more intriguing explanation. It references a study in which exercise caused increased hunger hormones in women (not in men). So we might conclude that women are sometimes made hungrier by the act of exercising itself.
Other studies have shown that young men might have their appetite blunted by working out. This data would also support what I see clinically. Most of my patients are women. In general, men lose weight faster and seem to get a greater benefit from exercise than women do. This leads me to the following recommendation: Do whatever you can exercise-wise that allows you to follow your chosen diet plan without deviation. Keeping calories low is paramount for weight loss, so if exercise is derailing you, you are likely doing too much of it. As I’ll talk about in a moment, exercise becomes much more vital in the maintenance phase. Imagine the exercise portion of your weight loss period as a lead-in, a kind of practice, for maintenance.
This brings up an interesting question. Why should exercise have a stronger impact on maintenance than on weight loss? After thinking about this all weekend, I had a Eureka! moment. We always say that weight loss and weight maintenance are two different things, but what we usually mean by this is that they take two different types of psychological focus. We’re probably not going far enough. It occurred to me this weekend that weight loss and weight maintenance REALLY ARE two completely different things. They seem to be continuums of one another because they are controlled by the same levers, diet and exercise. But they’re not.
As I’ve said before, weight loss is all about forcing your body to do something it is not genetically comfortable with: giving up stored fat. The body behaves as if it’s ignoring that fat, working with whatever you give it to eat and adjusting to those ingested calories, no matter how low. Exercise doesn’t appear to change that equation much. It is only when you consistently convince the body that the food shortage is serious enough that it must burn fat that it will open up its fat flood gates.
Maintenance, on the other hand, is about energy storage, not fat breakdown. Now we are dealing with an entirely different system, the one I’ve called the IBM (Intake Balance Mechanism) . NOWs have a smoothly oiled auto-balance or IBM. This bodily system sends food either to be burned or to be stored. In NOWs, the system makes the correct decision no matter how many calories or how much exercise is added in. POWs gained weight when their auto-balance gets stuck on “store”. For the POW, daily exercise appears to unjam this broken system, giving it a chance to run again. POWs will remain vulnerable, but will be vastly aided by exercise.
The “Times” article talks about an animal study that supports this view. After a group of rats that carried a genetic tendency to gain weight were purposely fattened, they were then dieted. Once they had lost weight, they were put on a maintenance diet and assigned to either run on a treadmill or remain sedentary. After eight weeks, they were allowed to eat at will. Sedentary rats ate heartily and regained their weight. “But the exercising rats metabolized calories differently. They tended to burn fat immediately after meals, while the sedentary rats’ bodies preferentially burned carbohydrates and sent the fat off to be stored in fat cells.” In other words, exercising animals burned rather than stored. Their auto-balance was restored, at least temporarily. We might conclude from this study that exercise oils the auto-balance enough to get us past periodic periods of diet indiscretion. I believe that’s true. But I’ve seen enough regain in 20 years to know that it takes only a moment for the levers to jam again and for fat to start accumulating. Thus, exercise, controlled intake, and proper food choice must be on the menu 80-90% of the time.
Well, I’ve gone on and on…as I always do…on this topic. There were other interesting tidbits in the “Times” this weekend. More on those in the next post.