I read your post and wondered - has he always acted this way?
Biologically - could he have sugar inbalances? I know I have a nephew who was REALLY mean hitting people, etc. Found out his blood sugar was dropping - hypoglycemia and he would lash out because he was feeling "out of balance" OR Could he be going through a growth phase and feels embarrassed that he is "eating you out of house and home". My eight year old is hungry all the time. He is very lean and possibly has a really high metabolism.
His world - Could he be having problems at school? Bullying, bad grades, doesn't like teacher, etc. Are your other kids treating him like the bad apple? Do your other children seem to do things effortlessly but for him things are more of a struggle? All of this could cause him to lash out. If he isn't treating you all with disrespect then that tells me that maybe he is going through something and "needs" you on his side but doesn't know how to tell you what's going on.
I don't know your situation and the only way to respond is to be presumptive, but could you sit down with him and say "I love you but it seems you are struggling with something. You are hiding food, lying to me, being disrespectful to your brothers and sisters. Is there something you want to talk about because this isn't the person you really are. Something seems to be stealing the hero (telling the truth, peacemaker, adventurer, etc.) part of you and as your Mom I want to know what that is and how I can help?"
Boys like to know that they are looked at like the good guys. They want to know you care about them and believe that they are better than what they are producing. Think of a husband that comes home frustrated from his job - he wants to know that he is better than his circumstances. Same with young boys I think.
Hope that helps. My 10 year old daughter and I prayed for you because I know it isn't easy raising kids. I also live in Texas so have an affinity for a fellow Texan mom!
Be encouraged. Kids do like boundaries and they DO want their parents involved when life gets overwhelming.