First weight training workout -- retaining water from inflammation?

After months of doing a good bit of cardio, I did my first weight training workout on Saturday. I have been SUPER sore for the past 2 days as a result. Today I noticed I gained 2 lbs -- my first gain since surgery -- despite actually eating fewer calories than usual the past week. I also realized at the end of work today that I'd gone 9 hours without peeing despite drinking constantly throughout the day. Is the inflammation from the workout causing me to retain fluids? I don't look swollen anywhere, but I don't know where else the weight (and lack of urine) could have come from. If so, does it get better with time? My plan is to go back to the gym Wednesday as long as I'm fully recovered, and eventually get up to 3 non-consecutive days per week.

Even before surgery, anytime I changed my workout routine - more intensity, more weight, more anything - I'd gain a few pounds. Same for me after surgery, although I don't gain as much or seem to hold onto it as long, probably because I'm not eating as much, nor am I eating the same foods that I did before (I was a pro at justifying a giant dinner, complete with appetizer and dessert, after working out)

Here you it explains everything.  No worries

http://www.livestrong.com/article/39379****er-retention-after-resistance-training/

Thank you, that makes perfect sense and describes everything to a T! I didn't notice any soreness until the next day. I'll start doing a little cardio warmup beforehand and stretching afterwards. It's good to know it's temporary!

Totally normal.  Muscle needs more water to function than fat.  The more muscle you build more water will be retained.  This also means you can have more weight fluctuations if you are dehydrated or retaining more than normal.   Keep at the exercise and the eating plan and everything will be fine.

Quite simply - yes.  Anytime your muscles are "sore" that signals inflammation.  And the body will hang onto every ounce of fluid for dear life.  It does get better with time.  Start slow, don't overdo and don't focus on the scale.  It's the worst indicator of how well you're doing.  

When someone starts a new exercise program, they often experience muscle soreness. This type of soreness is thought to be caused by tissue breakdown or microscopic tears in muscle tissue. When this happens, the body protects the tissue. Start using weight loss supplements regularly, and be honest.