Every month it seems the recommended daily amount of exercise changes. It’s 10,000 steps.
No, wait, it’s an hour.
Oh, no, 30 minutes is plenty, and you can even take breaks.
While few people really believe 10 minutes of daily exercise is enough, it turns out that for most of us trying to lose weight, 30 minutes isn’t enough, either.
A study published July 28 in the Archives of Internal Medicine adds to the burgeoning scientific consensus: when it comes to exercise for weight loss, more is better. It suggests that obese people would have to exercise at least an hour at a time to see any significant difference in their weight.
The study, led by John Jakicic at the Physical Activity and Weight Management Research Center at the University of Pittsburgh, followed nearly 200 overweight or obese women ages 21 to 45 through a two-year weight-loss program. The women were given free treadmills to use at home, regular group meetings and telephone pep talks to help keep them on track. Participants were also asked to restrict their food intake to between 1,200 and 1,500 calories per day, and were randomized to one of four physical activity intervention groups based on energy expenditure (either 1,000 calories or 2,000 calories burned per week) and exercise intensity (high vs. moderate).
By the end of the 24-month intervention, the women who managed to lose at least 10% of their starting body weight (which was, on average, about 193 lbs.) — and keep it off — were exercising twice as long as health authorities typically recommend and expending more than twice as many calories through exercise as women who had no change in body weight. The biggest weight losers were active a full 68 minutes a day, five days a week (about 55 minutes a day more than they had been before the trial began), burning an extra 1,848 calories a week.
The frustrating thing about media coverage of studies like this is how they dumb down the explanation, not differentiating between the amount of exercise needed for cardiovascular health and for weight loss. Me? I’ll be honest: I exercise to lose weight. At some point I hope to have lost enough that increasing the duration of my workouts in pursuit of cardio health will be possible, but for now I’m all about the numbers on the scale (and the size of my jeans).
So, just how much exercise does it take to lose weight? There really isn’t a set answer. As the study itself pointed out, the participantes used treadmills 68 minutes per day, but that was 55 more minutes of activity than they’d been previously getting.
In other words, their experience confirms what dieters all know, even if we try fooling ourselves otherwise:
Calories Out > Calories In = Weight Loss
Figuring out how many calories you should burn in a day to lose weight — assuming you continue eating the exact same way — is a matter of understanding your basal metabolic rate and taking in 15-20% fewer calories than your BMR and normal daily activities require. That’s it.
If you get bored exercising, as I do, the trick is figuring out activities that burn calories quickly. Grocery shopping, for instance, burns a mere .028 per pound per minute, meaning a 20 minute trip to the store for a 150-lb. woman will only burn 84 calories. That’s not even enough to work off a Snicker’s bar scarfed down on the drive home. On a treadmill at a 3 mph pace that same woman will burn 108 calories (.036 per pound per minute) in the same amount of time. But if she ratchets up the speed and runs 5 mph on her treadmill she’ll burn almost 200 calories.
So next time you run across an article telling you how many minutes of exercise you should be getting per day to lose weight, save yourself the time and skip it. It’s not about the numbers on the clock, it’s about the calories burned. Better to take those 5 minutes you’d sit reading that article and use them to jump rope, and if you happen to be a 150-lb. woman, you’ll burn 60 calories while you’re at it.
