When I first started teaching, I was working out in the studio a lot. I was also a scale junkie. Unsurprisingly, I was confused to see the number on the scale initially inch up, not down. Not much, a couple pounds. But it bothered me. So much so that I researched why then threw away my scale.
Workouts cause tiny tears in muscle fibers, it's why we feel sore after a new or tough class. The body naturally heals these tears through inflammation. The fluid required for this inflammatory response weighs something. It's temporary. i.e. Ignore it.
This inflammation can also cause the muscle to temporarily feel bigger in diameter. The key word here is patience, building lean muscle is a process. The work we do at the barre will first attack intramuscular fat (fat stored in the muscles) and push it outward. Be consistent & the intramuscular fat burns off to reveal more compact, toned muscles.
All our bodies trim down & tone up at different rates. And this is before factoring in what we are eating. Barre can be a great way to lose inches and/or weight. But it's important to keep in mind there are additional ways to measure these changes than on the scale (like how your clothes fit & how good you feel!)