When you think of exercise for weight loss, do you think about long, sweaty workouts — or short, half-hour workouts? Exercise science has long held that if you want to burn more calories and shed fat weight, you need to put in some serious fitness time, whether you’re running, walking, or enjoying a Zumba workout.
But a recent study questions that long-held assumption. A lot of ears — including mine — pricked up last month when the “lose weight with less exercise” headlines hit the media. Here’s what happened:
- Danish researchers recruited 61 healthy, sedentary and slightly overweight men in their 20s and 30s. They were randomized to a control group (no exercise), moderate exercise (~30 minutes/day), or high exercise (~60 minutes/day).
- Over the 13 weeks of the study, both exercise groups lost similar amounts of total weight and body fat. Surprisingly, those in the 60 minutes/day group had a negative energy balance (Calories burned vs. calories ingested) that was 20% less than expected. Even more surprising was the 83% higher negative energy balance in the 30 minutes/day group. These subjects were more physically active when they weren’t exercising.
- There were no statistically significant differences in calorie intake or non-exercise physical activity between the two groups that could account for the differences in negative energy balance.
Interesting, isn’t it? At first glance, these results look like a big win. I mean, we’re all busy — for many people, it’s hard enough to fit in 30 minutes of exercise a day, let alone 60. So does this mean that if you’re working on weight loss, you should keep your workouts to 30 minutes to optimize fat loss?
Maybe. It’s a small study, and there are many unanswered questions — would we see the same results if a person completed two 30-minute workouts a day? Will the results hold true for people who aren’t healthy, sedentary, slightly overweight young men? What about significantly overweight post-menopausal women, for example?
I feel way more energetic after a 30-minute vs. a 60-minute workout. After a longer exercise session, I’m more prone to sit around, feeling I’ve earned the right to put my feet up. In fact, I’ve even gone straight to bed several times after completing 10K or half-marathon races. I’m also less careful about what I eat after longer workouts — again, that feeling of self-righteousness emerges. I wonder whether or not the 60-minute subjects were keeping accurate food records.
A shorter workout may also result in a larger calorie deficit in the long run because you can exercise at a higher intensity. Longer workouts are, by necessity, lower-intensity workouts. That might explain part of the difference.
Keep in mind that weight loss isn’t the only good reason to exercise regularly — and getting more than the recommended minimum of 150 minutes of exercise a week is linked with even greater health benefits. For lasting weight loss and maintenance, the most important thing about exercise is to make it a permanent part of your lifestyle, whether your workouts are short, long, or a combination of both. Even so, exercise alone won’t get the job done — you’ll have to make sustainable changes to your eating habits as well.
But if you’re curious about what shorter aerobic workouts could do for you, why not give it a try? Maybe 30-minute workouts are a better fit for your schedule; maybe you’ll enjoy them more. And, who knows — you might even lose more fat and reach your weight loss goals more easily!
How much do you exercise daily? Have you noticed this result with your own weight loss efforts?
- Rosenkilde M, Auerback P, Reichkendler MH, Ploug T, Stallknecht BM, Sjodin A, Body fat loss and compensatory mechanisms in response to different doses of aerobic exercise — a randomized controlled trial in overweight sedentary males, Am J Physiol Regul Integr Comp Physiol, 2012 Sep;303(6): R571-9. Epub 2012 Aug 1.
Beth Shepard, MS, ACSM-RCEP, ACE-PT, has a master’s degree in Exercise Physiology from the University of Arizona. Beth is an expert in fitness and health promotion and a certified wellness coach, helping people thrive by adopting sustainable lifestyle changes. She and her family love to hike, bicycle, and try new sports.