Study: What Burns More Fat, Aerobic or Strength Training?

Photo by Ben Draper

When it comes to losing weight, there are a million different theories on what exercises are most effective. Some swear by running, others stick to weights, and a lot of us mix it up. And now researchers are stirring the pot even more: A recent study in the Journal of Applied Physiology found aerobic training may be more efficient than resistance training when it came to burning fatEffects of Aerobic and/or Resistance Training on Body Mass and Fat Mass in Overweight or Obese Adults.Willis, L.H., Slentz, C.A., Bateman, L.A., et al. Duke University Medical Center. Journal of Applied Physiology, 2012 Sep 27..

The Study

Researchers conducted an eight-month study with 119 overweight, middle-aged adults. The first group performed aerobic exercise (approximately 12 miles a week of running, biking, and swimming), the second lifted weights (three sets, eight to ten reps per day of eight resistance exercises, three days per week), and the third group did both (lifting three times a week and aerobic training roughly 12 miles per week). The results found the aerobic and combo groups lost more weight and fat than the resistance-training group.In fact, the strength-training group actually gained a little weight over the course of the study.

Can We Trust It?

Kind of. Before everyone throws out their barbell or starts shouting (we know people have strong feelings about this), let’s back up a bit. The strength-training group did gain a little weight, but at least some of that was due to an increase in lean muscle mass. Moreover, increased muscle can speed up metabolism, which over time can help shed fatEffects of cross-training on markers of insulin resistance/hyperinsulinemia. Wallace, M.B., Millis, B.D., Browning, C.L. Human Performance Laboratory, United States Sports Academy, Daphne, AL. Medicine and Science in Sports and Medicine, 1997 Sep;29(9):1170-5.Exercise improves fat metabolism in muscle but does not increase 24-h fat oxidation. Melanson, E.L., MacLean, P.S., Hill, J.O. Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Denver, Denver, CO. Exercise and Sport Science Reviews, 2009 Apr;37(2):93-101.Effects of aerobic vs. resistance training on visceral and liver fat stores, liver enzymes, and insulin resistance by HOMA in overweight adults from STRRIDE AT/RT. Slentz, C.A., Bateman, L.A., Willis, L.H., et al. Div. of Cardiology, Dept. of Medicine, Duke Univ. Durham, NC. American Journal of Physiology Endocrinology and Metabolism,2011 Nov;301(5):E1033-9. Epub 2011 Aug 16.. The group who did both aerobic and resistance training also gained lean muscle. Resting metabolic rate was not measured in this study. Another factor not regulated in this study was diet, though participant food intake was tracked throughout the eight months through food questionnairesAerobic and resistance training effects on energy intake: the STRRIDE-AT/RT study. Willis, L.H., Slentz, C.A., Bateman, L.A. Division of Cardiology, Duke University Medical Center. Medicine and Science in Sports and Exercise. Med Sci Sports Exerc. 2012 Oct;44(10):2033-9.. Overall, participants in the aerobic and combined groups decreased their reported food intake over the eight months, with decreases occurring in the amount of fat, carbs, and protein eaten. For the resistance training group, energy intake dipped only very slightly.

Since diet wasn’t controlled over the eight months, it’s difficult to predict the results had participants eaten the same foods and amounts across groups. The groups who gradually ate less lost the most weight, suggesting part of aerobic training’s advantage over resistance training could be in reducing appetite. Still, we shouldn’t toss the research aside. This isn’t the first study to compare the effectiveness of cardio versus strength training. Another study done about a year ago (with the same researchers) found similar results: Aerobic training was the best way to burn fat in the shortest amount of timeEffects of aerobic vs. resistance training on visceral and liver fat stores, liver enzymes, and insulin resistance by HOMA in overweight adults from STRRIDE AT/RT.Slentz, C.A., Bateman, L.A., Willis, L.H. Div. of Cardiology, Dept. of Medicine, PO Box 3022, Duke Univ. Medical Center, Durham, NC. American Journal of Physiology -Endocrinology and Metabolism, 2011 Nov;301(5):E1033-9. doi: 10.1152/ajpendo.00291.2011. Epub 2011 Aug 16..

Why It Matters

While there’s been a lot of talk about this study, the results actually aren’t that mind-boggling. Perhaps the biggest takeaway should be that the combo group lost weight and built lean muscle mass — rather than the aerobic group losing the most fat. Sure, when looking in the short term, science has shown aerobic training is a great way to lose a little weight. Cardio — especially quick sprints — can help burn fat, decrease the risk for cardiovascular disease, and improve psychological well-being tooEvidence based exercise – Clinical benefits of high intensity interval training. Shiraey, T., Barclay, G. Australian Family Physician, 2012 Dec;41(12):960-2.Acute psychological benefits of aerobic exercise: a field study into the effects of exercise characteristics. Rendi, M., Szabo, A., Szabo, T., et al.Faculty of Physical Education and Sport Sciences, Semmelweis University, Budapest, Hungary. Psychology, Health, and Medicine, 2008 Mar;13(2):180-4.. But if burning fat is something we want to work on over time, lifting weights is important, too. An increase in muscle can amp up metabolism, not to mention boost self-esteem, increase strength, and improve sleep. And after all, the group that completed both aerobic and resistance training each week lost fat while building lean muscle mass. The bottom line? Now there’s even more evidence for something we’ve known for awhile: Exercise, whether hitting the weight room, hitting the roads, or both, is probably a good idea.

What do you think? Have you seen better results from aerobic training or resistance training? Let us know in the comments below or tweet the author @lschwech.