I only have two sets of dumbbells- a 10 lb weight set and a 25 lb weight set. Going to the gym isn't really an option right now. Is there a way to transition from 10 to 25 lb weights without intermediate sizes? I'm trying to gain strength, endurance, and yes- muscle mass. Can I gain significant strength and muscle mass from just doing body weight exercises? If so what are some good ones to do?
Bodyweight is never a bad idea. Nerdfitness has some good info on bodyweight exercises.
Here's a beginner set:
Here's an advanced set:
Light weights, more reps (to fatigue.)
As for actually transitioning between those two sizes, pick a point and, once you hit that point, just switch. You're probably working out in sets of three (it seems like most people do), so just be ready to drastically scale down the number of reps you do in a set once you move up. Instead of doing three sets of eight with the 10 lb. weight, do three sets of two with the 25 lb. weight. Though, to be honest, if you're doing three sets of eight at 10 lbs., you can probably do more than six total reps with the 25. Just listen to your body--don't do something you can't handle, but don't be afraid to push yourself up to your limits.
For the bodyweight exercises, I should ask what you mean by 'gain significant strength.' I love bodyweight exercises; it's most of what I do, and you will get stronger in the sense that you will be able to lift more after you start than before. But if you want to 'gain' strength in the sense of muscles that appear larger, from what I understand that has more to do with making sure you eat a lot of the right things than with what kind of workout you do.
If you start with bodyweight workouts, I highly recommend the NerdFitness stuff that Matthew Williams posted. As for specific exercises: squats, lunges, pushups, pullups, planks. Make sure you've got the form correct--it's better to do five with correct form and correct depth than fifteen that you half-***. There are lots of variations to those exercises to make them easier or harder, so you should be able to find something that works for you. For example, you can start with pushups on your knees, move to incline pushups, move to standard pushups, move to decline pushups, and then move on to more exotic variations (one-handed, explosive, dive bomber, etc.).
Read around and find what exercises you think will work for you. Then, watch some YouTube videos for the exercises, to make sure you're doing them correctly. I really can't stress enough that you want to get the form spot on. Bad squat form, for example, is asking for knee problems.
You can get great results from consistent and proper bodyweight training, but you won't gain real mass without lifting heavier. When you're able, you should look into Stronglifts 5x5 program.
Took the words right out of my keyboard.
You can get in awesome shape with bodyweight only, and I'm sure strength too, but if you want muscle mass you have to hit the heavy weights in a good, basic program such as the one above.