A lot of people love to ride but also use it as a way to get fit and trim up. There is a saying that if all you have is a hammer then everything starts to look like a nail. As mountain bikers we tend to try and look at how the mountain bike can solve our fat loss problems when the truth is it may not be the best tool for the job. If you really want to trim up then you may need to prioritize the strength and interval training for a while and get your rides in as you can.
If body composition is something you want to improve I would say that you have to do the intervals 3 times a week and preferably get strength training in 3 times per week. The key to fat loss is to increase your metabolism 24 hours a day, 7 days per week. Strength training and intervals help you do that while mountain bike rides help burn calories but can actually hinder your metabolism.
Muscle tissue is one of the most important factors in determining your metabolism so anything that decreases it also decreases you metabolism. Because mountain biking is very catabolic and burns muscle tissue as well as fat it can actually decrease your metabolism.
Yes, riding your mountain bike does burn calories and can help with fat loss but the best tools for fat loss are strength training and intervals. This is the basis for two of the most popular fat burning programs in the world, Craig Balantyne’s Turbulence Training and Alwyn Cosgroves Afterburn Training. If you are trying to use mountain biking as the centerpiece for a fat loss program you may not get the results you want as quickly as you want.