Frustrated - Gained after exercising.... Is it muscle?

I going to assume you are still eating the same as before. The weight gain is most likely water retention. When you first start an exercise program this can happen. You are working your muscles in a way that they are not used to. Lifting weights, running, biking etc, if you are starting something new that the muscles are not conditioned for they have to work harder to complete the exercise. When you workout it causes micro tears in the delicate muscle fibers. That can cause water retention. When I start something new, or add more weight, or skip workouts for a few weeks & go back to them, I can always guarantee that I will have water gain.

Other things that can cause water weight gain are sodium, sugar and sometimes lack of hydration. I know it sounds weird, but if you are not drinking enough fluids the body will try to retain them. Sodium and sugar are water magnets. The more you ingest into your system the more water the body holds onto to dilute it. The body is all about regulation and homeostasis. Personal example, if I have more than 1500mg sodium and too much sugar, as in more than MFP suggests, I get edema and my feet, legs, and sometimes hands will swell up.

Hope this helps. Feel free to ask if you want to know more :flowerforyou: All it takes is patience, consistency and tweaking here & there with diet & exercise. It's trial & error, and before you know it you will be seeing more results!