You should maintain consistent blood-sugar levels by eating either a meal or a snack every two to four hours. Most of us, because of our busy lifestyles, significantly under eat, consuming only two meals a day, or eat at such widely spaced intervals that our blood sugar goes up and down like a yo-yo which isn’t ideal for weight loss.
By having a meal or snack every few hours, you are keeping your metabolism going. Think of your metabolism as a campfire, if you don't keep placing firewood on the fire, the fire will eventually burn out. Your metabolism is the same way, keep feeding it and it will continue to burn and be fired up. Prolonged hours of no feeding will cause it to slow down.