Cardio vs. Resistance Training for Fat Loss
Recent research out of the University of South Florida aimed to address the often debated question of which mode of exercise is more effective for fat loss: cardio or resistance training?
Research Question
The systematic review (which is when researchers pull a ton of studies that meet certain criteria and then compare them all) looked at studies that evaluated three groups: 1) resistance training, 2) aerobic training, and 3) concurrent or combined training (both resistance training and aerobic training in the same week).
Both aerobic training and resistance training contribute to fat loss in different ways. Aerobic training reduces fat by placing the body in a caloric deficit, when accompanied with proper nutrition. Resistance training enhances metabolism by increasing muscle mass. Because muscle is an active tissue, having more muscle contributes to a higher resting metabolic rate (RMR) and thus, more calories burned at rest.
Researchers wanted to know how these methods compared - specifically, if concurrent training contributed to greater fat loss since both methods were utilized within the same time frame.
While fat loss may not be the goal for everyone who exercises, everyone benefits from knowing how all types of training affect their metabolic health as a whole.
Studies included in this review examined adults 18y and older, free of metabolic and/or chronic disease. Exercise interventions lasted at least four weeks and include a concurrent training group. The analysis included studies that were designed as a randomized controlled trial, using the aerobic training and resistance training groups as controls to compare to the concurrent training. This ensured that each control group only participated in their assigned mode of exercise (e.g. aerobic participants did not lift weights). Lastly, studies reported body mass or body fat at baseline and post-intervention.
Results
When compared to resistance training, aerobic training results in greater reductions in body mass (i.e. overall weight) and body fat mass, but preserves less fat free mass (muscle).
This makes sense, as in the absence of muscle building, body mass (weight) as a whole decreases, so muscle loss is part of that process. Similarly, greater weight loss occurred in the aerobic training group, when compared to the combined group, but changes in body fat weren’t evident.
When work-matched (e.g. same level of effort) comparisons across all three groups were analyzed, no differences in weight, fat mass, % body fat, or fat free mass were noted. Controlling for similar energy expenditure in all three groups indicates that all three modes of training provide similar body composition outcomes.
For fat reduction, aerobic and combined training both were more effective than resistance training alone. Adding in resistance training did not enhance or deter from fat loss. Ultimately, while aerobic training, greater weight loss may occur, likely explained by the energy expenditure that is evident across various intensities of aerobic training. Combined and resistance training programs generally have breaks buffered in, which may inhibit energy expenditure. However, aerobic training comes at a cost: the preservation of fat free mass.
Resistance training has been touted as the best way to enhance your excess post-oxygen consumption (EPOC). However, research has demonstrated that exercise intensity, not mode is the driver of this phenomenon.
Practical Application
If the goal is preservation of muscle, then resistance training should be incorporated into training programs. However, if equivalent fat loss is desired, then increasing the duration of combined training programs may be necessary.
Circuit training that increases heart rate while lifting weights can offer a greater metabolic demand than resistance training alone. But, if you’re only lifting weights with zero to very limited cardio, you’re not going to achieve the same fat loss outcomes that aerobic exercise offers. Plus, your heart health is going to suffer.
If the goal is to reduce body mass or body fat, aerobic training should be prioritized. These changes can be adopted in the short term (<10 weeks) to focus on a specific body composition outcome (i.e. weight loss), and then subsequently adjusted to meet training goals as needed.
Both of these are important implications for exercise professionals working with clients and for the general public as a whole. Knowing how the training decisions that you make affect your body is a critical first step in becoming an informed exerciser.
Simply Fit is a free, weekly newsletter written by Dr. Amanda Durall, a Kinesiology professor, fitness professional, and busy mom of three aiming to simplify exercise science and deliver practical recommendations to help you achieve your fitness goals. Want more free content like this delivered straight to your inbox? Subscribe for weekly training tips, technique overviews, and more evidence-based fitness content!