My calorie intake for two weeks has been 1,560 (I'm on the "Lose it" iPhone App) and on the 4th week of my C25K program also. I haven't strayed from my diet at all, I'm making sure to always eat all my calories. My period doesn't start till next Saturday. So far I've steadily gained 3 lbs (just checked this morning) since last Saturday, which was 3 weeks prior to my period coming.
All I've been reading is that water weight gain before a period is usually 5 days before. So this just seems way off if I started gaining weight since last Saturday.
Is it the running or do I have to lower or raise my calories? Could it be that I've gained 3 lbs of muscle from the running program? I'm doing a brisk walk (using a treadmill) at 3.5 mph and my runs are 4.2-4.3 I honestly doubt that could be it but I'm just trying to figure out whats going on here.
I measured this morning and found that I've gained inches around my waist (1 inch), hips (1 inch), and ankles (1/2 inch). Everywhere else (arms, neck, bust, rib cage, thighs) has remained the same.

I'm just frustrated because I feel like the only time I can check for weight lose is the week after my period ends and the whole other time my body is gearing up for either the impending period or is recovering from one.

Any chance your periods could be messed up? When I start or stop exercising, my cycle goes WAY off. In fact, I'm already two days late this month because I started exercising on a regular basis again.

If there is something going on hormonally, your periods could affect you for about 3 weeks out of each month. Two weeks before and the week of and then bam, one good week. I was like that for years.

Interestingly, the new diet changes and exercise have seemingly made mine better.

If it continues, you may just want to have it checked out.

ugh..i hate premenstrual weight gain--I can go as high as 5 lbs. I think y ou definitely are retaining water. The thing is right before your period starts all the hormones that cause the releasing of blood by cutting off blood supply to the endometrium also cause you to release that water. I pee all day right before my period.

I just started going through the pee thing last night. I think I woke up 4-5 times. By the third time I though "okay, I know I didn't drink that much fluids yesterday.
The hormonal thing is making me think. This will be my third period since having my son, he's 7 months now. And I used to have (I say used to because since November 2003, I was either pregnant or nursing) to have symptoms of PMDD. Not sure if it's coming back, I stopped nursing my son when he was 3 months. Which for the first time has left me on my own to lose the baby weight. Not sure how soon you start retaining water when you have PMDD though.