I've been on my weight loss journey for a year.
My goal of 160lbs is in spitting distance.

But I have a serious question. Why have I gained so much in the course of 9 hours?
Daily, I get out of bed, use the bathroom and weigh myself, all before I eat breakfast.
Please take a look at the following photos. The ones in the pink boxers were taken at 10 am this morning. The ones in the black shorts were taken at 7:45 pm.
Clearly there has been some substantial weight gain. So I will explain my day. I woke up, weighed in and took the pics with the pink boxers.
I ate a cup of yogurt, toast and milk (skim of course).
Then I drove over to my mother's house and did yard work.
Then at about 3pm, I went to a diner and had french toast and hash browns and pink lemonade. Then I came home, putzed around a little bit, then I drank a bunch of water, went for my jog, then got back and, drank more water then did sit ups and leg lifts.

At 10 am.
http://i26.photobucket.com/albums/c1...i0/Photo70.jpg
http://i26.photobucket.com/albums/c1...i0/Photo71.jpg

At 7pm
http://i26.photobucket.com/albums/c1...i0/Photo72.jpg
http://i26.photobucket.com/albums/c1...i0/Photo73.jpg

I want to say that this weight gain is due to water retention. Hopefully that is it and if so, How do I reduce it?

Ok, first of all, I'm not seeing this "substantial weight gain" that you're talking about.

However, that said, your bodyweight can vary by anywhere from 2-10 lbs over the course of the day.

Eating something high in sodium can cause you to retain water or bloat. Hard physical exercise can cause your muscles to swell up. Some people are sensitive to certain foods containing gluten or wheat or even just regular carbs and that can cause water retention and bloat.

Diner food is notoriously high in sodium ... I suspect you're retaining water.

The way to get it to stop is ( a ) pay closer attention to your sodium intake and ( b ) drink lots of water to flush out the sodium you've put in your body.