Diet Detective: What do you think it is about a person's thoughts, beliefs, and intuition that might be making them fat?

Christopher Chabris and Daniel Simons: What goes on in our mind can be divided into roughly two types of processes: automatic ones and reflective ones. Automatic processes are fast, intuitive, based on emotions and preferences, and tend to live in the here and now. Reflective processes are slower, more analytical, based on logic, and often involve planning for the future or recalling the past. When eating, people often have conflicting goals: satisfying immediate desires and anticipating the consequences of what they eat for their future weight and health. Our modern environment is not well-suited to maintaining a balance between those goals, because it is easier than ever before to acquire tasty calories in high volume. The automatic system is “turned on” by all these options, and it is difficult to override our desire to eat something right now based on the reasoning that we will regret it later.

Diet Detective: In what ways do you think your theory might apply to people who are attempting to change their eating habits or begin a diet?

Christopher Chabris and Daniel Simons: The automatic processes that control much of our behavior are “opaque,” meaning that we can’t use our mind to figure out what they are doing and how they are doing it. But that doesn’t stop us from trying to figure out how they work, and that leads us to faulty conclusions about our own mind. Take, for example, what we call “the illusion of memory.” When we effortlessly recall an event in vivid detail, we mistakenly assume that our memory is complete and accurate. Often, though, our memories are far from accurate even when it feels like we can replay them in our mind. This is why it’s a good idea, when you are trying to lose weight, to write down everything you eat. It’s also important to realize that concrete goals are better than abstract ones. Our mind can handle abstract information, but it’s not as easy to deal with as concrete information, and when you are trying to lose weight, you should do everything you can to make the process a comfortable one for your mind. Don’t just say you will become healthier; say you will lose weight. Don’t just say you will lose weight; say exactly how many pounds. And then translate that into a set number of calories, “points” or whatever per day or week. That’s a concrete goal that you can record your progress towards and get constant feedback on, uncontaminated by the illusion of memory. Chris used this approach and actually lost 53 pounds without doing any serious exercise.

Diet Detective: Your book discusses several “everyday illusions” that “profoundly influence our everyday lives.” How do some of these illusions help or hurt a person's ability to lose weight and maintain the loss?

Christopher Chabris and Daniel Simons: Attention: The illusion of attention tells us that we are better at paying attention and noticing important things around us than we really are. We also tend to think that doing tasks well requires less focused effort than it does. People may not realize how hard it is to stick to a diet over the long term. It requires more mental effort than we usually expend in our everyday lives, and we tend to underestimate how much effort we will need to accomplish our goals. Confidence: We tend to think that confident people are more skilled, knowledgeable, and competent than they really are. This is true of the diet gurus we see on TV. We are too easily seduced by their confident sales pitch (“con man” is short for “confidence man”), and don’t think critically enough about what they’re selling. Potential: The illusion of potential is the mistaken belief that we all have vast reserves of potential that are easy to unlock. A corollary is that it is simple to achieve great change in your life. Miracle diets tap directly into this belief. Slowly losing weight by making long-term lifestyle changes is much less appealing than an immediate “cleanse” that will work wonders in a few days or weeks.

Diet Detective: Towards the end of the book, you write about “the real way to unlock your potential.” How might you apply this concept to healthy living?

Christopher Chabris and Daniel Simons: The best advice we can give is to recognize that your own mind might deceive you into doing things you will regret later. If you make your goals concrete, keep track of everything you eat, and recognize that losing weight takes time and effort, you’ll be more likely to succeed. Setting a daily calorie budget and tracking everything you eat is a great way to start, and it might prove to be all you need to fend off the automatic processes that lead to weight gain.

Now a couple of personal questions.

Diet Detective: What would you choose for your last meal?

Christopher Chabris: There are so many things. But I would probably take one regular slice, one Sicilian tomato-basil slice, and one sausage, pepper, and onion sub from Pinocchio’s Pizza in Harvard Square.

Daniel Simons: I’d skip the meal and go for some chocolate fudge brownie ice cream.

Diet Detective: What’s your favorite “junk food?”

Christopher Chabris: I like them all, but lately I seem to have a weakness for gummy worms. Not gummy bears. Just gummy worms.

Daniel Simons: I have a weakness for chocolate Teddy Grahams.