Well, there probably is a reason this is happening if you look a bit closer. You said in another thread that you have been hitting the gym hard, doing some intensive work there. There's a clue. Whenever you start lifting heavy weights and/or doing an intensive amount of exercise, you can hold water-weight.
Some people can even gain a few lbs in muscle weight, esp at the beginning (so I have been told). I know that happened to me in my first stint at the gym -- I gained 10 lbs in muscle weight, but lost over 2 sizes in my clothes and dozens of inches over my whole body.
Plus, you have not told us exactly how much you are eating and drinking. We need to know the numbers to help you with that. Aging can slow your metabolism down a bit; meaning you may need less calories each day to maintain your weight. You also have to watch how much salt you eat as that can cause your body to hold water too.
So can your hormones, even if you are 37 years old; unless you have gone into early menopause for some reason. Again, that can cause you to hold a few lbs in weight too, although that should be only temporary.
EDIT2ADD: I just remembered that some medications and illnesses can cause some people to gain weight too (although you didn't mention that in your post). Plus, there is a phenomenon called "Rebound Weight" where someone has been eating really low calories (say only 800 a day), then they binge or up their intake to 1200 or more. This can cause you to rebound or regain some weight. It will take some time for the body to adjust to the increase and level out.
Sooo, now you can see that there may be several reasons, and/or a combination of things going on here. You need to track what you are eating and drinking (meaning, write it all down) so that you can figure out what is going on for sure.
help, my body is gaining weight for no reason...
