The other day as I was reading through my myriad of newsletters I came across this article looking at the activity level of hunter gatherers. Of course there was also plenty of new coverage on the Olympics that had exercise on my mind as well. It reminded me of another set of questions (and complaints!) that I get from people are trying to lose weight and/or improve some other type of health condition they have. The question/complaint usually goes something along the lines of "Well, if I eat more can't I just exercise more later?" or "I can't lose weight because I can't exercise" or "I've been working out like crazy with the elliptical/treadmill/Zumba class and I still haven't lost much weight."
In the article listed above (you read it right, you're not just taking SkepticRD's word for it?) there is a study done on people who appear to be a lot more active than those of us in the "west." You would think that with all that daily activity that they would be burning tons more calories, especially since they have a much lower body fat percentage than their western counterparts. But the physiologic studies indicate that that's simply not true. Now naturally, because the authors of this study are trying to be good scientists, the conclusions that were drawn had to do with inherited physical traits in relation to totally energy expenditure. They were opening up the door for more scientific research on how our lifestyles impact our energy expenditure and therefore our body weight as well. SkepticRD, however, does think this article poses some interesting information that we may be able to include in our own quests for better health.
One thing that can be gleaned from this is that most of us are not burning as many calories as we think we are. For example, if SkepticRD walked a 20 minute mile, keeping up the same pace for an hour, which is a pretty fast walk, she would burn---a whopping 200 calories! All I would have to do is eat two pieces of bread, or an ounce of nuts, or an "energy bar" and I've just taken in what I've "burned" off if not more. In other words, many people suddenly feel they are fat burning machines just because they have gotten on the treadmill. And related to this, many people are not really paying attention to how much or what they're taking in. For example, in just about every diet plan I've evaluated nuts will be listed as a healthy snack, but every ounce (roughly a cupped palmful) contains about 180-200 calories. So, if you eat the whole bag of nuts (you know who you are!) and still do that hour on the treadmill; well, you're probably not dropping any clothing sizes soon. In other words, your magical thinking about the exercise you did and the not paying attention to how much you ate does not add up to helping you lose any weight.
Another reason that your exercise might keep you from losing weight is that you might not have really stopped to think about what you are taking in. Hunter gatherers eat what's available to survive. Most of us in the west have a lot more choices, but for a variety of reasons people don't pay attention to where those extras might be creeping in. One of the times where I see people having the most trouble is with foods that are labeled "healthy." Let's take fruit for example as I have seen plenty of people who have their blood glucose and weight loss goals thwarted by not paying attention to fruit. One cup of watermelon pieces has about 12 grams of carbohydrate and about 50 calories. Given that I have patients who can down at least half of a watermelon in one sitting, it really adds up. I've also had a lot of patients who have had trouble with commercially prepared snacks that carry a healthy label. One time SkepticRD actually subscribed to a company that would send me a sample of dairy/gluten/soy free snacks once per month. I thought it was a great idea to try new snacks without buying in bulk, but pretty much every box contained things that were way over the carbohydrate limit that this insulin resistant gal could eat. I stopped it so I wouldn't even have the temptation in the house. Think about, we as skeptics are very critical about what goes into our minds, but a lot of us stop scrutinizing when it comes to our food.
On a related note, some people when they start exercising also start using products that are not made for the average "I exercise to try to get healthy" person. One of these is sports drinks such as Gatorade, etc. There is no evidence that people who exercise for under 45 minutes need to replenish the sodium beyond what they might get in your diet, and you've just undone whatever work you did in that past 45 minutes. (Link) Another product is protein powders. Once again, people who are exercising to be healthy do not have protein requirements that are really higher than anyone else. Remember, even excess protein can eventually cause trouble with blood sugar control as can the fact that you are consuming a food like substance that will be absorbed quickly and likely leave you feeling hungry later.
A third problem that people have, even when they do try to change their diet, is that intense exercise actually just serves to make you hungrier. I think this tends to be more true of people who were used to eating a lot of sweets and starches—many people do not feel good when they cut these out because their bodies are used to have readily available blood glucose for energy and their body has not adjusted to using to breaking down fat for energy. (Some people call this detoxing—if you use that word SkepticRD will take your Skeptic card from you!) If you do intense exercise that you are not used to doing, that will also cause you to quickly use up any available glucose causing you to feel hungry (or "hangry") and all you can think about during and after your workout is EATING A GIGANTIC PLATE OF PASTA DAMMIT! (Not that SkepticRD knows what this is like, no, not at all). So, you will be much better off allowing your body to get used to a change of diet first and starting off with light walking, etc.
Keep in mind too, that the high level competitive athletes whom you are watching at the Olympics didn't get there by eating a poor diet. Sure, those athletes might get to eat a bigger piece of chicken than you, or eat a bigger sweet potato, but they usually eschew sodas, deep fried foods, snack foods, etc, especially when they have an important competition coming up. Now, if someone has a job that requires that much athletic training and he or she STILL has to be careful with what he or she eats to avoid gaining extra fat, then think about how much more careful those of us who are doing moderate exercise have to be!
Speaking of professional athletes, one of the other exercise fallacies that is touted by gyms is that by building muscle you will actually increase your resting metabolism. Unfortunately, in order for you to actually achieve this benefit, you will need to bulk up like Lou Ferrigno or Ms. Olympia 2012 Iris Kyle. In other words, unless you are a highly competitive athlete you won't get enough of an increase in resting metabolism to justify the extra cookies. (Link)
So, does this mean that exercise does not confer any benefit? No, moderate exercise, especially exercises that help you build muscle, can improve your sensitivity to insulin, which very important for controlling the blood glucose levels in the pre-diabetic and Type 2 diabetic, lowering your risk of heart disease, and might even ultimately regulate your appetite (Link). If you are an older adult or hope to someday become an active older adult exercise can help you build strength, maintain bone density, improve your balance, improve your coordination, keep or improve your mobility, reduce your risk of falling, and help you be more independent throughout your life cycle. (Link). And for some people, well, they just want to look better naked.
Bottom line—the evidence points to diet as the greatest impact on body fat loss. Keep exercising to improve your strength and maintain quality of life, but those hours on the elliptical won't help.