500 rounds of 5.56 loaded into strippers and bandoliers packed into a canvas shoulder bag along with a half dozen magazines, followers, and a cleaning kit weighs 19.8 pounds. Water weighs in at about 6 pounds (close enough) to a gallon. You can't operate without water and I figure on at least a quart an hour in the heat of the day.
You're going to have to weigh your own weapon and body armor. Assuming you have a fighting vest, figure in the ammo that's preloaded into your magazines.
And that's just stepping off your porch to go pick a fight.......
If you have to scoot, think about your git kit. My summer kit weighs about 25 pounds, my winter gear is about 10 pounds heavier.
Are you up to this? Does your everyday excercise or job give you the strength and stamina to deal with reality when your world suddenly falls to pieces?
If you can't remember the last time you walked more than a mile, you're screwed, plain and simple.
I'm not telling you to go on an extreme excercise regimen, but at least get yourself in good enough shape to outlast any unexpected situations. Walk instead of driving to the corner store. Take the stairs. Do your own yardwork and fire Jose.
Oh yeah. Drop 20 pounds.