3. He's on a "see-food" diet. He sees food and wants to eat.
Guys are known to respond to visual cues, especially when it comes to food and sex. But recent research shows that even people who have been very heavy and then lost weight still respond chemically even just to the sight of food. Their neurochemicals get more readily stimulated simply from seeing a piece of gooey, chocolate cake, for example. They automatically start to salivate in response.
People who are thin or who never have been overweight don't automatically "have to eat" just because they see tempting food — more ammo for keeping weight down.
4. Our upbringings affect our eating habits. Family eating styles and habits can really impact our interactions. If like me, you grew up with your family getting together eating leisurely and talking around the dinner table, it can almost feel like an insult when he wants to do just the opposite — eat in front of the TV like his family did for many years.
5. Past experiences resurface. It's very possible that the emotions from traumatic past life experiences can carry through energetically into the present and, subtly or not so subtly, impact behaviors like eating. For example, if he withheld food from others or was taunted with food by other people in a previous existence — say when food was really scarce — it might make him more prone to have anxiety around food or reach for the security of food this time around.
6. We've all evolved different brain chemistries. Eating for other reasons, such as emotional fulfillment, for example, is one of a number of complexities often involved in bad eating habits and the overweight, diabetes, arthritis, cardiovascular and other health problems that often follow.