Like most people, I have two desires—to satisfy my food cravings and to live a healthy, long life.

When I was a teenager, I was skinny, so I didn’t worry about getting fat—I just fed my body what it craved. Every weekday before I left the Orange Daily News to deliver my newspapers, I would walk next door to the jewelers and put a dime in his pop machine to buy my bottle of Coke. Then, biking to my paper route, I would stop at the gas station and buy a Heath candy bar. Another time I bought a quarter pound of fudge, took a chaste bite, and then ate the whooole thing in ten minutes. [Stupid, but it was totally worth it].

Even today, I favor the ice cream and chocolate food groups over leafy vegetables, carrots, or peas. My wife, the voice of reason, fights a long-term battle against my cravings. She cooks wonderful, healthy meals, but I still major on desserts. She says, “I give up! Eat what you want. But don’t expect me to take care of you when you get sick.” (Empty threat.) She’s already picked out my tombstone epitaph—“I tried to tell him, but he wouldn’t listen.”

Despite all I’ve learned about nutrition, despite the scientific evidence, despite my wife’s rational suggestions, I still eat junk food.

There’s a reason I eat this way—I’m an expert at self-deception (SD). I tell myself: “I eat better than my friends,” “I’ll eat better next week,” “I know a guy who ate junk food and lived into his 90s,” or, “Just this one time; I’ll take just one piece.”

Do I believe these lies? Well, it’s complicated. The best explanation is that I believe the lie now. (Why spoil a great experience!) And just after eating, I can repent and believe the voice of reason. This allows me to enjoy my junk food and still preserve my self-respect—to see myself as a rational, disciplined person who will make good (future) decisions. But of course, that’s a lie also, and my fake resolve doesn’t motivate me to change my behavior.

Why do we do this? SD is always motivated—you have reasons to deceive yourself. You self-deceive because you want something. What you want is to have your cake and eat it too, so you act on one conviction that contradicts a more important conviction. You want to satisfy an immediate desire or give yourself permission to violate a moral code.

SD works because of our compartmentalized brains. Each of us has a “reptile” brain (hippocampus)—older, simpler, and associated with instinctual behavior, such as “fight” or “flight.” In addition we have a new brain (“neocortex”) that is rational and deliberating, the part of our brain that says, “Wait a minute—will this serve your long-term interest?” We can call the hippocampus “Junior,” and the neocortex “Mother.” Junior does what Junior wants to do; Mother does what she plans to do. SD occurs when we let Junior win over Mother.

But why worry about a little innocent SD?

Because it’s not innocent. The stories above show how SD can be dangerous to your health. SD promotes lazy, habitual eating that may lead to addiction. SD represents a divided care for yourself, and works against a healthy, integrated personhood. Most seriously, it tempts you to “self-divinize”— to substitute your own flawed judgment for God’s.

What to do about SD? How combat the voice of Junior and listen to Mother’s voice?

First, I need to continually remind myself to focus on the long term, to remember that I’m constantly investing for the future, and to focus on behaviors that will enhance that future.

Second, it helps if I can find an accountability partner—a brave, faithful friend who will hold me accountable, who will constantly tell me the truth and call me out when I’m self-deceiving.

Third, I can reward myself when I’ve made a good decision. Like Mother used to say, “If you eat your carrots and broccoli you’ll enjoy your dessert more.”

Finally, I can listen more to the voice of the Spirit, that voice that knows me most intimately, cares most deeply about me. I can base my choices, not on my desires of the moment, but rather on God’s highest, best purpose for me. My body thinks it knows what’s good for me, but the Spirit knows even better.