Eating too much after swimming

i basically just started a few days ago , ive been swimming all my life but always for fun . For the past 3 days i have been going down to the pool and swimming 30 pools , the pools are only about 20-25 meters long. but i've noticed that after swimming i get super hungry and make 2 sandwiches , then i cook some chicken or meat 30 minutes later . any advice or some articles online about this would be great also i do 4 kilometers or miles (depending what the treadmill is set to) walking before i go into the pool , is that a good idea? and if someone could give me some advice on what to eat , how many times a day. im looking to lose some weight not too much though im 6"3 180 pounds and got no muscles , i want to get some ripage in . thanks