Weight gain

Let me preface this by saying these are observations that I've noticed for myself, especially at the beginning of a new training program. I am not an expert, and am also male, so my body may react different.

It depends on what type of training you are doing in the gym and what you eat regularly. It is pretty normal for me to gain some weight when training. A small portion of this is muscle, lots of it is water. If you are eating a balanced diet with good portions of complex carbs, then your muscles are going to hold onto that water like crazy, especially if you salt your food!

I've experimented with my diet and observed weight changes without increasing/decreasing in clothes sizes. For example:

I tried Keto for 3 weeks and lost 12 lb. After going back to a moderate carb diet (fruits, vegetables, grains), that weight bounced right back. I began weight training, and put on another 8 lb in a few weeks. My clothes still fit the same. On high carb days, or days where I eat too much salty snacks, I notice that my weight is on the higher end of my fluctuating weight range.

My advice is to continue to carefully observe your weight. If it continues to climb at a steady rate, it might be worth tracking your food for a week to see if there are some sneaky calories in your diet. Otherwise, if your clothes still fit and you like how you look in the mirror, keep doing what you're doing!