I noticed this morning that I have gained five pounds. Conventional wisdom says it's time to shell out to join a gym, or if I want to save money, dust off that jogging stroller.

But what does conventional wisdom know? A recent article in Time magazine points out that our belief that exercise is essential to weight loss is a recent development, and — this shocked me — not well supported by research.

That's right: For most people, exercise is useless for weight loss.

It sounds like complete crazy talk, yet the article cites solid-sounding research and academic experts saying just that. One recent study looked at overweight women, some of whom were assigned to work out with a trainer for different lengths of time, alongside a control group that did not work out. They didn't change their eating habits. All the groups on average lost weight, but the women who worked out did not lose significantly more than those who didn't.

What's going on?

The study's authors cite "compensation." That is, working out makes you hungry, so you eat more. You also might move around less for the rest of the day after you work out. The article also points out that most people overestimate how much food they can indulge in before they have consumed more calories than they just burned in their workout.

This would explain something that has baffled me since chidlhood: The overweight mail carrier. My dad delivered the mail as a kid, and I never understood how many of his colleagues, even though they were on walking routes, not driving routes, could have such big bellies. The answer, apparently, is that being out on that route all day made them very hungry.

All this leads me to think about the growing emphasis on "being active" in America right now, coming from everyone: from the schools to the scapegoats of childhood obesity, like children's television and McDonald's itself. The hope on McDonald's part seems to be that society will be OK with kids consuming their megacalorie meals as long as they do some jumping jacks first.

Look at the great amount of resources expended for the cause of physical fitness already. While I am not disputing that it's unhealthy to be sedentary, the experts quoted in this article contend that the kind of free exercise that we have traditionally incorporated into our day is just as healthy as organized sports for kids and treadmills for adults.

The article even quotes the head of Harvard's Prevention Research Center on Nutritional and Physical Activity wondering if the whole McDonald's playground idea was a ploy to get kids to eat more.

"I know it sounds kind of like conspiracy theory, but you have to think, if a kid plays five minutes and burns 50 calories, he might then go inside and consume 500 calories or even 1,000," Steven Gortmaker told Time.

Once I started thinking about it, I realized that working out is expensive in many ways. It might be worth it (at least for some people) if it increases your overall sense of well-being or prepares you for an activity you enjoy, like touring cities on foot or climbing a mountain. And of course, many if not most people who work out do it so they will look better and be more attractive than the gym rat on the machine two rows over. But in order to decide if something is worthwhile, you should take an honest look at what it costs.

Gym Fees

The most obvious, and most avoidable, cost of fitness. For those who have joined the extreme home workout trend, those 30 Day Shred and P90X DVDs ain't cheap either.

Time

This is a major one for parents of small children like me. If a leisurely walk with my children is as good or almost as good for me as an hour at a gym with them in the daycare, I'm unlikely to choose the latter. And with my husband already away from the kids for 10 hours or more on a weekday, does it make sense for him to use one of the remaining hours at the gym?

Increased Calories Consumed

People who work out for weight loss set out to burn calories they won't be replacing. But it doesn't usually work out that way, simply because our bodies are programmed to prevent that from happening. And what about people who work out to build muscle mass and intentionally increase their caloric intake to help build it?

I recently saw an exhibit at the Museum of Science and Industry showing everything various Chicagoans ate in a day. One was an iron-pumping construction worker who consumed something like 12,000 calories, much of it protein. He obviously felt that the cost of purchasing all that extra food was worthwhile, but in a world where we are increasingly conscious of the environmental toll of food production, is it really sustainable for some people to consume six times as many calories as are needed for healthy survival?

Injuries

With all the talk about how healthy it is to stress your cardiovascular system, but there is little talk about the increased risk of injury that occurs when one switches from a brisk walk to lifting weights, running, or participating in sports.

As for those five extra pounds I'd like to shed, I'm now planning to cut back on the ice cream and walk my next errand rather than drive it, rather than set aside time for a daily workout. I still plan to join a local gym once my baby is a little older, but mainly because it offers a fitness activity that I truly enjoy: indoor rock climbing. After reading that article, I am a lot less likely to force myself through any fitness routine that I loathe in the perhaps unrealistic expectation of great weight loss and health benefits.

For those who work out in an organized fashion, do you feel that the benefits exceed the costs?

This post contains affiliate links to Amazon.com, which will surely increase my sense of well-being if you use them to shop.