4 week old son acts hungry constantly. for example he just ate 5 oz of formula and acts still hungry. i am worried he is overeating what do i do?

Feeding: The best way to sort this out is to have him evaluated by his MD. He will check his growth, including his weight and make sure he is growing well. Babies vary in how much they eat and at times will eat more because of a growth spurt. If he is over eating his weight will be excessive and often he will spit up frequently. Babies also need to suck and temporary use of a pacifier may be helpful.

Pain not hunger: Newborns do not inherently over eat, and they will normally stop sucking when their body has had the amount that it needs to grow. Infants who eat excessively or seem to be constantly hungry are often reacting to the discomfort of things like acid reflux. Sucking and swallowing comforts them, and temporarily relieves the pain. Thus the vicious cycle of overeating and worsening reflux begins.