If you get stronger, you'll get bigger and as you get bigger muscles, you'll be able to use more resistance. Likewise, if you use specific movements that are the usual barometer of strength such as the deadlift, squat, or bench press or their machine equivalents, you'll get as strong as you're going to be in these traditional movements. Of course you can. Being defined means having a low percent body fat and has virtually everything to do with the number of calories you consume in a decent healthy diet and your genetics. Getting defined doesn't involve eating lots of supplements either.
Nothing is required except a healthy diet.
If you need to gain weight, you slightly increase calories. If you want to lose body fat, you slightly decrease calories. For an example of eating Real Food instead of using supplements, click here . For an example of a good workout that takes minimum time, look at My Favorite Routine . It's not the be all and end all.