Just joined this site,dont know if I am on the right section .Im sure every one here knows bowflex,Im 46 male and want to better my self,3weeks ago I weighed 200lbs and a36 waist,Im 6ft,I lost 25lbs. and 33 waist. My question is can I gain muscle mass by push my self harder or do I have to start lifting iron weights.
20min a day, 3x a week
Just be consistent, don't miss workouts, learn how to eat, get plenty of rest, and get in the habit of lifting. You will outgrow the bowflex soon enough and will start to look at that iron with "I want you" in your eyes.
25 pounds in 3 weeks? That's a sign of the flu, massive water weight loss, or an amputation. It's not going to be sustainable, but congratulations.
I have no idea how a bowflex actually works. But if you can still add weight (or bows, whatever) then you can still make progress.
If you max out the bows, then you're going need to hit the iron. See that as a 'graduation'.
You can probably gain muscle mass with the Bowflex for some time if you slow your rate of weight loss down to about 1 lb per week. This would not be true for someone more advanced in training, but having just started it can be true for you.
If you try to sustain a rate of weight loss anything like what you've done so far, you will not be able to gain muscle at the same time, or very little.
I've used a bowflex before, in my experience it's a good start. That said, you'll probably max out the weights fairly quickly on some of the exercises. I was bench pressing "225" for reps on the bowflex, but when I started going to a gym and using free weights, I couldn't do more than 135.
Also, from what I can remember the bowflex manual advocated a "high carb, moderate protein, low fat" diet.