However, the average exerciser looking to improve body composition can lose fat while improving lean body tissue over time and beginners will likely get the greatest benefits of both fat loss and muscle gain. In fact, one study found that women who followed a cardio and strength program for 6 months lost an average of 10 percent body fat while increasing their muscle by about 2.2 percent, while another study showed that men experience similar improvements after following a 16-week strength training program. This shows that beginners respond quickly and efficiently to strength training and cardio.
The key is to keep a balance of both cardio and strength training, whether you're a beginner or a more experienced exerciser. Doing all cardio with no strength training can compromise your muscle mass, while doing only strength training without cardio can compromise your fat loss. If you're in that situation (e.g., a marathoner or a bodybuilder), your goals and training approach may be different. For the average exerciser, however, having a balance between the two is the best way to maximize fat loss while preserving muscle mass.
Layman, Donald K., et al. (2005). Dietary protein and exercise have additive effects on body composition during weight loss in adult women. The American Society for Nutritional Sciences J. Nutr. 135:1903-1910, August.
Are you losing muscle as well as fat?. The Facts About Fitness. Retrieved March 6, 2006 from http://www.thefactsaboutfitness.com/news/exerpro.htm
Nindl B, Harman E, Marx J, et al. Regional body composition changes in women after 6 months of periodized physical training. J Appl Physiol. 2000 Jun;88(6):2251-9.
Treuth M, Ryan A, Pratley R, et al. Effects of strength training on total and regional body composition in older men. J Appl Physiol. 1994 Aug;77(2):614-20.