Also by Ian Ayres


Carrots and Sticks: Unlock the Power of Incentives to Get Things Done


Lifecycle Investing: A New, Safe, and Audacious Way to Improve the Performance of Your Retirement Portfolio


Super Crunchers: Why Thinking-By-Numbers Is the New Way to Be Smart


Optional Law: Real Options in the Structure of Legal Entitlements


Insincere Promises: The Law of Misrepresented Intent


Straightforward: How to Mobilize Heterosexual Support for Gay Rights


Why Not?: How to Use Everyday Ingenuity to Solve Problems Big and Small


Pervasive Prejudice?: Non-Traditional Evidence of Race and Gender Discrimination


Voting with Dollars: A New Paradigm for Campaign Finance


Studies in Contract Law


Responsive Regulation: Transcending the Deregulation Debate




The $500 Diet











The $500 Diet:


Weight Loss for People Who Are Committed to Change





Ian Ayres




Copyright © 2010 by Ian Ayres


All rights reserved.










For Lisa Sanders,

friend and physician



AuthorÕs Note

This booklet is a companion to the book Carrots and Sticks: Unlock the Power of Incentives to Get Things Done. In these pages, I tell you in a bit more detail about my own struggles with weight loss, and lay out advice for how you can use commitment contracts to safely lose 10 percent of your body weight. YouÕll learn about my seven-step plan to a happier and lighter you. Most important, I tell you what you should do to keep it off. I check in and provide updates on the weight-loss efforts of some people we first met in the book and some other folks weÕll meet for the first time.

            Most diet books are written by physicians and scientists, but IÕm a contract lawyer and an economist who uses the tools of my crafts to help you change how much you want to eat.

            Carrots and Sticks provides the background social science evidence for how to best tailor incentives. It shows how the behavioral revolution is helping people strengthen their resolve in a host of professional and personal settings. This booklet is a how-to guide that applies the wisdom of Carrots and Sticks to a personal health problem that has national and international ramifications.


The $500 Diet


MN006135HairlessHarrier1.jpgChapter 1: The Hairless Harrier

Text Box: Ian at seventeen and about 177 pounds. (The Hilltop, 1976)In 1976, my high school newspaper published an unflattering photograph of me running shirtless with the caption ŅHairless Harrier.Ó I was mortified. I was painfully thin, almost emaciated. For years, people had said I must be hiding a pirateÕs treasure somewhere, because I had a sunken chest. One of my summer bosses asked me to keep a shirt on when I was working outside. When I graduated from college, I had a Lincolnesque physique—like our sixteenth president, I was about six foot four and 180 pounds—but without any of his rail-splitting sinews.

            The good news was that I could eat prodigious amounts of food without getting fat. My sainted mother would regularly make me mastodonic breakfasts consisting of eight pieces of bacon, eight pieces of toast, four eggs, and four crpes stuffed with vanilla ice cream then smothered with hot maple syrup.

            I was master of the Ņquick jam,Ó a way to prepare and consume a huge number of warm gooey calories in just a handful of seconds. I taught my friends how to make Ņpop Õem up eggsÓ in our familyÕs first microwave oven. While two slices of bread were toasting, I would use the microwave to poach an egg in a small bowl of melted butter. I had just enough time to scarf down one molten cholesterol sandwich while the makings for the next one were being zapped by this electronic wonder of culinary science.

            In 1987, when I was twenty-eight and took my first academic job at the American Bar Foundation in Chicago, my eating habits used to appall my abstemious boss, Bill Felstiner. Bill was in his fifties and rightfully proud about his conscientious diet and low cholesterol numbers; I would make a point of sitting next him and downing an entire pint of HŠagen-Dazs Rum Raisin with my lunch.

            But just about the time I turned thirty, everything changed. ŅI was completely broad sided by the fact that your body doesnÕt act/react the same way as you get older.Ó This quotation is from baseball great Curt Schilling discussing his own midlife-onset weight problems,1 but it applied equally well to me. Suddenly, for the first time in life, I could gain weight. I started growing what in Chicago is sometimes referred to as an Ņalderman,Ó a paunch of fat around the belly. This was particularly unattractive because I remained Biafrically thin in my chest. I remember getting on the scale at the home of my friend and coauthor Peter Siegelman, and finding out that I suddenly weighed more than two hundred pounds. I couldnÕt believe it.

            Almost immediately, I went on a crash diet. It wasnÕt that hard for me to skip meals and starve myself, some days combining just one meal with two extended workouts. I perversely became fascinated with pushing the envelope to see how little I could consume before my body would rebel at being deprived of sustenance. The pounds just melted off me. I lost about five pounds a week. In a little over a month, I was back to my fighting weight and a better self-image.

            As I look back now, my conduct seems borderline anorexic. It is not safe to try to lose more than two pounds a week. Moreover, it doesnÕt teach you anything. When I was fanatically dieting, I was probably eating enough to support a body weight of just 160 pounds. No wonder the pounds were flying off me. But it wasnÕt sustainable and it didnÕt teach me what eating enough to support 180 pounds feels like. The vast majority of people who lose weight quickly end up regaining it.

            I was no exception. Within a couple of years, my weight again ballooned.

            No problem, I thought. IÕd lost weight easily before. IÕd just go on another crash diet. The problem was that this second time around, my body crashed. I deprived myself to the point of exhaustion, but didnÕt feel better even when I allowed myself to eat a second and third meal each day. Even after a good nightÕs sleep, IÕd wake up enervated.

            I was now teaching at the idyllic Stanford campus and falling in love with the woman whom I would soon marry. But I was having trouble pulling myself out of my diet-induced torpor. When I broke down and went to see a doctor, I learned that I had mononucleosis. It was a good half year until I was feeling myself again.

            I canÕt know for sure that starving myself caused the onset of my mono, but it sure didnÕt help. DonÕt get me wrong. I wasnÕt so enervated that I stopped teaching or writing. In the ensuing years, Jennifer and I had two sweet babies. I ended up happily teaching at Yale. Overall, these were the best of times..

Text Box: Ian in his forties and his third or fourth time over two hundred pounds. (Anna Ayres-Brown, 2006)            But my weight kept yo-yoing. IÕd diet and lose weight. Then IÕd become inattentive. IÕd stop getting on the scale for a couple of months. At some point, IÕd realize that it had been a while since IÕd checked my weight. And often there would be a few more weeks when I would avoid weighing myself because IÕd be scared about what I would find. When I finally did get on the scale, IÕd usually find that IÕd gained back half of what I lost. And IÕd throw in the towel, gaining weight until I would be so filled with disgust that IÕd begin the cycle again—the only variation being that with each cycle, I would plateau at a higher weight.

            This story is at once deeply embarrassing to me and also painfully commonplace. The boring truth is that IÕm just one of millions of people who start to put on pounds in midlife and unsuccessfully struggle to take them off.

            Things didnÕt really change until the beginning of 2007. Once again, I was filled with self-disgust and massively out of shape. I had stopped exercising that previous fall, and my weight had ballooned to 205 pounds. I plugged my height and weight into a body mass index (BMI) calculator and was aghast to learn that this skinny kid from Kansas City who couldnÕt put on a pound to save his life in high school was now officially overweight (with a BMI greater than 25).

            I resolved once again to get back to 180. But this time I did something different. I backed up my weight-loss resolution by putting $500 at risk each week for the entire year. To start off, I had to lose a pound a week until my weight dropped below 185. And then I had to keep my weight below 185 for the rest of the year. (I really wanted to weigh 180, but I figured I should give myself a safety cushion of 5 pounds to account for normal fluctuations.)

            HereÕs what happened over the next year:




Tracking IanÕs Commitment Contract


You can see that my weight went from 205 down to 180 in about ten weeks. This is not something to be proud of. Losing weight at a pace of 2.5 pounds of week was a bit slower than my craziest diets of the past, but still too aggressive. My good friend and author of The Perfect Fit Diet, Dr. Lisa Sanders, told me frankly, ŅYou know youÕre going to gain it back.Ó

            Dr. Sanders, who also runs an obesity clinic, knows of what she speaks. People who diet routinely lose weight for three to four months. But the safe money is always on them regaining it in the remainder of the year. For example, look at this chart comparing a two-year randomized study of the impact of Weight Watchers:


Source: Stanley Heshka, et al., ŅWeight Loss with Self-Help Compared with a Structured Commercial Program: A Randomized Trial,Ó Journal of the American Medical Association 289(2003):1792–8.


            The chart compares the results of people interested in dieting to lose weight, who were randomly assigned to two different approaches. The lower line (marked ŅWeight-WatchersÓ) shows the average weight loss of the Weight Watchers diet group, while the upper line (marked ŅSelf-HelpÓ) shows the average weight loss for the control-group dieters, who were given information on a healthy diet and exercise program.

            People on Weight Watchers were able on average to lose twelve pounds after six months. But by the end of two years, almost half of the weight was regained. The point here isnÕt to beat up on Weight Watchers. Study after study of all kinds of diets shows exactly the same pattern—initial success for three to six months followed by a very substantial regain of the weight during the next year or two. The depressing truth is that only about one in five successful dieters are able to maintain a 10 percent weight loss through the end of the year.2 It is hard work to join the 10 percent club, but itÕs even harder to remain a member. So what is remarkable about my weight loss in 2007 isnÕt that I lost weight; itÕs how steady my weight remained for the rest of the year. It was during these remaining forty weeks that I was teaching myself what it feels like to eat a 180-pound diet.

            Even if you keep the weight off through the end of the year, youÕre still not out of the woods. It takes at least two years to reset your body clock to a new level of consumption. Maybe the most depressing news is that even after two years, people in the 10 percent club still have about a 50 percent risk of regaining the weight.

            ItÕs still not clear what side of the 50 percent IÕll end up on. In my case, my weight remained remarkably flat for about two years. But toward the end of 2009, it started creeping up again. I had stopped putting money at risk and I had stopped regularly getting on the scale. IÕm pretty sure it never went above 200, but I might have flirted with 190. Even after many months of maintaining a 180-pound diet, I found it all too easy and enjoyable to start having seconds and thirds. The teenager who loved his ice-cream-infused crpes and his pop Õem up eggs still yearns to be set free. There are no guaranteed lifetime memberships for the 10 percent club.

            This booklet shows you how you can increase your chances of sustaining a healthy weight for the rest of the years of your life. If you are overweight, it sets out a plan that will give you a better shot of joining the 10 percent club and remaining a member. It is a very different kind of diet plan, because it doesnÕt tell you how much to eat or exercise. You are smart enough—with the help of the Internet and dozens of dieting books—to figure that out. WhatÕs unique about the $500 Diet is that it works on another dimension. It lets you change your own incentives to lose weight.

            When I finally confronted the fact that my success was slipping, I went back on the diet. And with very little psychological or physical discomfort, I rejoined the club. This morning, October 14, 2010, I weighed 179.2 pounds. (You can check whether I currently have $500 at risk and my current weight by searching for my name at


Chapter 2: The Plan

Could you lose a pound in the next week to keep from losing $500?

            That simple question is at the heart of the $500 Diet.


You can download the complete book for Kindle here.