The planet is 4 times the mass of earth; so because of its gravity, I'd weigh 600 pounds
You are probably just trolling and I'm falling for it by correcting you, but just in case you actually think this. . .
No. Four times the mass does not imply that you would weigh 4 times as much unless the planet's radius is the same as the earth's. That is quite unlikely. A planet with 4 times as much mass as the earth is almost certainly going to be proportionally larger in volume as well. Gravity is proportional to mass, but inversely proportional to the square of the distance from the center of that mass. In the end, if the planet is made of the same sort of rocky material, it will have a similar density, and thus similar gravity.
Would it be exactly 1G? Probably not. Without knowing the planet's volume, we can't know exactly. But a number between .8G and 1.2G is much more likely than 4G.
Of course, I'm assuming that you weigh 150 pounds here on Earth. If you currently weigh 500 pounds, then I apologize. . . your estimated weight on this new world may have been fairly accurate after all. :)