For a long-term weight loss, should you choose aerobic or resistance training?
For a workout of similar or equal length and intensity, you will burn more calories during an aerobic workout than during resistance training. However, the calories that you will burn throughout the rest of the day could tip the scales in favour of resistance training…
The metabolic enhancement that results from a workout lasts on average three times longer when the activity focuses on muscle building, versus endurance training.
A study published in 1977  revealed that the gradual decline of the basic metabolism due to ageing is largely caused by the loss of muscle mass that begins at around age 35. Resistance training slows this process and may even build new muscle, which helps maintain a more rapid metabolic function.
A Korean study  that compared a six-day/week fitness regimen of aerobic training to a combination of three days of aerobic training and three days of resistance training, showed that the combined program produced the best results for reducing surface and abdominal fat, and increasing muscle mass.
A study  headed by Duke Medicine physiologist Leslie H. Willis led her to conclude: "No one type of exercise will be best for every health benefit. However, it might be time to reconsider the conventional wisdom that resistance training alone can induce changes in body mass or fat mass due to an increase in metabolism, as our study found no change."
The Duke researchers added that recommendations for exercising depend on age. For older adults with muscular atrophy, studies have found that resistance training alone may still be beneficial. However, younger adults in good health or those who want to lose weight will obtain better results by undertaking aerobic endurance training.
In conclusion, regular exercise that combines both resistance and aerobic training can increase your metabolism so that more fat is consumed during and after training, even while you sleep!
 P. Tzankoff], AH Norris. Effect of muscle mass decrease on age-related BMR changes, Journal of Applied Physiology : Respiratory, Environnemental and Exercise Physiology, 1977, 43(6), 1001-1006.
 K. Park et al. The effect of combined aerobic and resistance exercise training on abdominal fat in obese middle-aged women. Journal of Physiological Anthropology and Applied Human Science, 2003, 22(3), 129-135.
 Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults. Leslie Willis, Cris Slentz, Lori Bateman, Tamlyn Shields, Lucy Piner, Connie Bales, Joseph Houmard, William Kraus. J Appl Physiol, Dec 15, 2012 113:1831-1837.