Well, I used to have the same problem around 3 years ago. I decided to go to the gym, which was the best decision of my life. I started with 1 hour of cardio, and 30 minutes of muscle training. When I lost a bit of weight with the cardio, I started working more on my muscles.
I mostly focused on my legs (around 45 minutes), then arms (30 minutes) and abs+back (20 minutes). After around less than two years, I was close to having a six pack (and I'm a girl! lol), could do 40 kg for my arms, and 170 kg for my legs.
And spoiler alert, I ate more than I did before!
I ate:
Morning: Sandwich + Yogurt or Eggs+Sandwich
10 am: Chocolate or fruit or biscuits
Noon: Rice or pasta with meat/salmon/shrimp. And let me tell you, it was a lot of it. Sometimes I ate sandwiches (similar to the subway ones, but self-made and healthier) + biscuits or chocolate or crackers
4 pm (before gym): (two) muffins
6 pm (after gym): dinner, which was mostly meat, fish or pasta
After 6 pm: some snacks like fruit, crackers sometimes dessert, and occasionally a sandwich when I was hungry.
So I ate around 2,5 to 3k calories on a gym day, and yet I had some nice muscles and felt better than ever. I even looked and felt better than 'friends' who were on a diet by counting their calories. They did not lose weight, because they still ate processed foods and drinks (juices, coca cola, biscuits).
The trick here is eating the right things, and making sure they are fresh + working out. Sure I ate a lot, but I ate eggs, rice, salmon, chicken, vegetables, a lot of fruit,... And sure I ate biscuits, muffins and chocolate. But the biscuits were either self-made or high quality, the chocolate was also high quality. The muffins were bought from the baker, very fresh too. And most importantly? I only drank water, tea (the warm one), and ice tea once or twice a week.
That in addition to going to the gym 3x a week (around 5-6 hours/week), and I had the body I desired.
So I would say, follow those tips, and you will feel very well. If you can't go to the gym, try swimming or any other activities.
The results are not 'quick quick', because that is just very impossible. It will take you a few weeks or months of hard work, but once yo get there, you'll be very happy.
I sadly let myself go during quarantine, but I am resuming my routine now, and can't wait to look like I did one year ago. Good luck!