So Fed Up with Water Retention

Overt he past 6 months my weight has been up and down, up and down. I need to lose about 10 lbs and every time I start losing something happens that thwarts my efforts. I am hypothyroid and recently learned that my tsh numbers are high-ish and we are working on getting those down a bit lower. Also went through an elimination diet for a month or so trying to figure out possible food allergies, none came up. So now I find myself at the highest weight I have been in a long time. Had a great week - sticking to my 1400 cals a day, allowing 200 extra Friday and 400 on Saturday because I ran several additional miles and did some good outside work. I was feeling really pumped yesterday - I didn't fall of the wagon over the weekend, committed myself to staying on track and had all my foods planned out. It was nice to eat a little extra, but at the same time, I felt I earned it. I am 5' 9," run or walk 4 miles every day and have started weight training again which is long overdue.

So, the problem is that I woke up 3 lbs heavier this morning. I know it's water. My fingers are fat and you don't gain 3 lbs of fat overnight (I hope!!!). But I just don't understand what causes this type of water retention, and I find it so incredibly demotivating, even when I know it is temporary. I am so committed to finally getting to my goal weight of 147 and with the increase in my thyroid meds I am feeling better than I have in months and months. It's a gorgeous sunny day and I am going to go on a 6 mile walk with my dog and life is good... except I am sick and tired of this water retention thing and this struggle to lose. Anyone else struggling with this intermittent water retention thing? Find any solutions? This is not a hormonal, time of month thing. It can happen any day at any time and I just can't figure out what triggers it and how to avoid it. Can't track it to salt, can't track it to carbs (I don't think). I do wonder if my work out yesterday which was much harder than usual, may have triggered it. Ijust wish I could better understand the mechanism so that it is not always such a surprise when it happens and so incredibly demotivating.

All that being said, for the first time in a really long time, I am still committed to staying on track for the whole weekend and not letting this stop my enthusiasm for getting to my goal weight (13 lbs). Bump in the road, but one that really p*sses me off! Thanks for all the great stuff you all post here. I have lurked for a long time now, but now that my meds are kicking in and I am feeling so much better and energetic I feel like I can really do this.