Almost every day, there’s a new study that comes out with sensational headlines that “proves” a certain way of training is better for fat loss than another. For example, a Duke study was published a couple of weeks ago that researched whether cardio vs weight training is better for weight loss.
The authors came to the conclusion that, “…It appears that AT (aerobic training) is the optimal mode of exercise for reducing fat mass and body mass, while a program including RT (resistance training) is needed for increasing lean mass in middle-aged, overweight/obese individuals.”1
The media took this story and ran with it. Hundreds of headlines popped up like:
- Cardio burns more fat than weight lifting (Star Tribune)
- Aerobic Exercise Bests Resistance Training at Burning Belly Fat (Duke Health)
- Cardio burns more fat than weight lifting (CNN)
…to name just a few.
With a reputable university behind the study and the media fervently promoting it, you are led to believe that if you want to lose fat optimally, you should only do cardio training.
This article explores several reasons why this conclusion may not be as sound as the authors claim it to be…to put it lightly.
Cardio vs Weight Training: Duke Study Weaknesses
1) Is Cardio Really “Optimal” For Fat Loss? – If someone said they are going to the gym 3 days per week for 8 months in order to lose weight and fat, but only lost 3.6 pounds of fat, would you say that was a good workout routine? Well, the people in this research study did just that. When the researchers claimed that the “optimal mode of exercise for reducing fat mass” they claimed that the aerobic training group who lost only 3.6 pounds of fat in 8 months was the best way to do this. As anyone who has taken on a fat loss program knows, an average of less than half a pound of fat lost per month equals really poor results.
2) Questionable Diet Protocol – In this particular study, these “weight loss” participants were told to adhere to a 2100 calorie diet, yet were overweight or obese to begin with. A diet of 2100 calories for someone who’s overweight or obese, would be a low calorie diet that, in and of itself, would cause weight loss. In this study, the researchers used a 3-day food diary and a 24-hour recall, two methods that have been shown to be poor predictors of actual calorie consumption, especially when dealing with an 8-month weight loss program.
3) Cardio Group Did Not Burn The Most Fat – The researchers claimed that the aerobic training group was the group that lost the most fat, but in actuality it was the combination group who lost 5.4 pounds of fat (they also gained some muscle). This is still not a huge amount of fat loss over 8 months, but is better than the aerobic only training group.
4) Weight Training Exercise Selection Not Very Effective – Researchers only stated that the resistance training group used 8 machines that worked the entire body. In college, I worked at a commercial gym, where they put a “circuit line” of 8 strength machines, 4 of which included single-joint movements. For example, this line included a preacher curl machine, which only works the biceps and a tricep extension machine that only worked your triceps. The other 2 isolation exercises were a leg extension and seated hamstring curl machine. These machines have their utility, but for the most part, should be used sparingly and really only for those with body building pursuits. If on the other hand, you’re trying to lose weight, you want to do as many multi-joint, free-weight movements as possible. The multi-joint exercises will induce more intensity and cause you to work more muscles, therefore increasing muscle burn.
5) Weight Training Routine Not Very Effective – In addition to that, these circuits took anywhere from 10-12 minutes to complete the 8 machines. Three rounds of these 8 machines would take a total of 30-35 minutes. In this study, three rounds of 8 machine-based exercises took an hour, about 15-20 minutes longer than it took the aerobic group in the study. It was also 25-30 minutes longer than it took people to complete the circuit I was supervising nearly 10 years ago.
This leads to 5 major weaknesses with this study. Overall, the aerobic group lost less than a half of pound of fat per month (not week). Food intake was not really controlled, which plays a very important factor when trying to lose fat. The intensity of the resistance training group was probably a lot less than it should be when doing a comparison of the cardio vs. weight training workouts. Lastly, the cardio training group didn’t see the best results; the training group that included both strength and cardio did.
Cardio vs Weight Training: Duke Study Strength
Overall, the study still had strengths that would be used in an applicable real-world setting. It focused on non-active middle-aged overweight adults with basic workouts. Overall, this study was very indicative of what the “average gym-goer” does all too often. For example, many people who are not active simply hop on a treadmill for about 30-40 minutes while doing some machines afterwards. This is something I’ve seen all too often and these are the menial results they can expect to get for their efforts (less than 4 pounds in 8 months).
Cardio vs. Weight Training: Why Not Both?
Those in the aerobic group were able to maintain most of their muscle mass and lost fat, but what the study didn’t highlight are other benefits of resistance training or the combination of both, better known as concurrent training.
Other studies, with a more intense exercise protocol, have shown that weight training before cardio training enhances fat burning during the session2, and that overall resting energy expenditure is increased following weight training.3 These studies indicate that fat-burning is indeed elevated when it comes to resistance training, especially when the workouts are intense enough.
Also, recent research is indicating that concurrent training (both aerobic and resistance training), might be the best mode of exercise for fat loss.4 The largest issue with concurrent training is that it has the potential to lead to over-training, but this can be avoided by cycling more intense workouts with cycles of easier workouts.
Cardio vs Weight Training Conclusion
Overall, this was a study of what the average gym-goer would expect to see if they went in without any real direction or a smart program to help them in their fat loss efforts. Whether those workouts included doing only machines, hopping on a treadmill or a combination of both, the results you will expect to see would not be very significant.
On the other hand, if you’re willing to work out with more intensity, use more multi-joint movements, follow and be consistent with a smarter eating plan, you can expect to see much better results. This is especially true if you use a combination of both smart resistance training with some form of interval training.
- Willis LH, Slentz CA, Bateman LA, et al. Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults. J Appl Physiol. 2012;113(12):1831-7. ↩
- Kang J, Rashti SL, Tranchina CP, Ratamess NA, Faigenbaum AD, Hoffman JR. Effect of preceding resistance exercise on metabolism during subsequent cardio training session. Eur J Appl Physiol. 2009;107(1):43-50. ↩
- Ormsbee et al. Regulation of fat metabolism during resistance exercise in sedentary lean and obese men. J Appl Physiol. 2009 May;106(5):1529-37. Hat-Tip: Alwyn Cosgrove ↩
- Davis WJ, Wood DT, Andrews RG, Elkind LM, Davis WB. Concurrent training enhances athletes’ strength, muscle endurance, and other measures. J Strength Cond Res. 2008;22(5):1487-502. ↩