Try this for a moment next time you say or tell yourself its lunchtime.
Focus your attention on your area where you usually feel those hunger twinges. If you have lost touch with them it is that area just bellow your ribs and across the middle just under your diaphragm. Just pay it a little notice while you breath naturally and discover if you are even hungry or how hungry you really are. Maybe you just need a light snack or even just a drink of water instead of a full blown man size meal. Take this one step further by noticing what it is you really feel like, some clients that do this tell me that they discover their feeling tense and a little anxiety running round in there. Simply by doing this you are getting back intouch with you bodies own natural ability to protect you from over eating and not consuming higher amounts of energy fuel than you really need.