# How I Lost 100 Pounds Using TDT

Background Information: [Ingredients of Timeless Decision Theory](/lw/15z/ingredients_of_timeless_decision_theory/)

Alternate Approaches Include: [Self-empathy as a source of “willpower”](/lw/2yd/selfempathy_as_a_source_of_willpower/), [Applied Picoeconomics](/lw/ep/applied_picoeconomics/), [Akrasia, hyperbolic discounting, and picoeconomics](/lw/6c/akrasia_hyperbolic_discounting_and_picoeconomics/), [Akrasia Tactics Review](/lw/1sm/akrasia_tactics_review/)

Standard Disclaimer: [Beware of Other-Optimizing](/lw/9v/beware_of_otheroptimizing/)

Timeless Decision Theory (or TDT) allowed me to succeed in gaining control over when and how much I ate in a way that previous attempts at precommitment had repeatedly failed to do. I did so well before I was formally exposed to the concept of TDT, but once I clicked on TDT I understood that I had effectively been using it. That click came from reading Eliezer’s shortest summary of TDT, which was:

> The one-sentence version is:  Choose as though controlling the logical output of the abstract computation you implement, including the output of all other instantiations and simulations of that computation

You can find more [here](/lw/15z/ingredients_of_timeless_decision_theory/) but my recommendation at least at first is to stick with the one sentence version. It is as simple as it can be, but no simpler.

Utilizing TDT gave me several key abilities that I previously lacked. The most important was realizing that what I chose now would be the same choice I would make at other times under the same circumstances. This allowed me to compare having the benefits now to paying the costs now, as opposed to paying costs now for future benefits later. This ability allowed me to overcome [hyperbolic discounting](http://en.wikipedia.org/wiki/Hyperbolic_discounting). The other key ability was that it freed me from the need to explicitly stop in advance to make precommitements each time I wanted to alter my instinctive behavior. Instead, it became automatic to make decisions in terms of which rules would be best to follow.

With that as background, this is how I made it happen:

I was walking home from class along my usual route I had made a habit while doing this of stopping into Famiglia Pizza and ordering garlic knots. I like garlic knots quite a bit, but I also hated being fat and the way being fat made me feel. Things weren’t quite as bad on that front as they’d been a few years before but they were still extraordinarily bad. I thought about my impending solace and thought to myself: You wouldn’t be so fat if you didn’t keep buying these garlic knots every day.

I thought about that for a second, realized it was trivially true and then wondered to myself whether it was worth it. If I never stopped for the knots I would weigh less and feel better, but I wouldn’t have any knots. Even worse, I wouldn’t have any garlic. But would I rather enjoy today the full effect of never having had the knots, in exchange for not having any? Once I asked the question that way the answer came back a resounding yes. I didn’t know how much it would matter, but the calculation wasn’t remotely close. I walked right past the pizza place and never stopped in there for a snack again.

Using this method seemed like the most useful thing I’d come up with in some time, so I quickly extended it to other decisions starting with the rest of my diet. For each meal I would consume, I decided what quantity was worth it and forbade myself from ever consuming more. I motivated myself to stick to that rule in the face of hyperbolic discounting by reminding myself that I would make the same decision next time that I was making now, so I was deciding what action I would always take in this situation. More generally, sticking to the rules I’d decided to follow meant I would stick to rules I’d decided to follow, which was clearly an extremely valuable asset to have on my side.

I used two other major rules in what I like to call the “Don’t Eat So Goddamn Much, Shut Your Pie Hole” diet. The first was to cut down from three meals a day to two and eliminate all snacks except water, cutting my consumption by more than a third. I’d had practice skipping meals in the past and realized that skipping dinner was far less painful than it looked; within a few weeks I stopped getting hungry at night. The other change was to weigh myself daily and alter how draconian the rules were based on my current weight relative to my current baseline. If I was below the baseline, I’d lower the baseline and give myself a chance to cheat a little. If I was above it by too much I would cut out all meal options that weren’t “wins” in the sense that they had more calories than my average.

I tried incorporating exercise into this program but made the discovery many others have made that exercise didn’t correlate with weight loss. Exercise makes you better at doing exercise so long as you keep doing exercise, but it had no measurable effect on my mission so I decided to let that wait until after the mission was complete. Even then I found several exercise programs I tried to be not worth it compared to not having one, or found that they became so over time. Eventually I was able to find a trainer and I remain happy with that aside from the cost. I also considered changing what I ate, but found that beyond cutting out the worst choices that it was neither necessary nor worth the cost.

The last obstacle on the journey was that as I lost more and more I started to feel worse rather than better due to all of the excess skin that doesn’t go away on its own. It was only after I’d lost all the weight and [had the resulting skin removal surgery](http://www.emedicinehealth.com/excess_skin_removal_after_extreme_weight_loss/article_em.htm) that I suddenly got up and felt genuinely good about how I looked and felt for the first time in my life. I’ve since managed to relax a number of the rules but was never concerned I wouldn’t do what was necessary to keep myself on track.

Since then I’ve used similar techniques and rules in a wide variety of areas of life. It was only years later reading Less Wrong that I realized that I’d effectively been employing inter-temporal Timeless Decision Theory. That realization allowed me to better understand and formalize what I had done, and gave me a better framework for explaining it to others. A common and justified criticism of using TDT in everyday life rather than as a theoretical construct is to ask where one can find another TDT agent, or indeed any agent sufficiently causally linked to you so as to allow you to utilize that link. My answer to that is that whether or not there is someone else you are linked to yourself. You can be that other agent, the recognition of which can allow you to win and win big.

I am fully aware that to a first approximation dieting attempts that follow similar patterns never work. Most people do not have the willpower necessary to sustain them, or otherwise suffer too much to choose to remain on the diet long term. There are powerful forces working against such an attempt. My working hypothesis is that I had five unusual things working in my favor: I have extraordinarily strong willpower in such areas, I already had strong affinity for rule setting and abiding, I fully believed in what I was doing, I had a life situation that allowed me to experience temporary discomfort due to hunger and I thought of all changes from the beginning as permanent. At least some of these advantages are things that can be learned. If anyone is capable of following in my footsteps, it would be Less Wrong readers. In [New York’s Less Wrong group](http://www.meetup.com/Less-Wrong-Overcoming-Bias-NYC/) especially a lot of us have had success with various different approaches, and I think that developing mental techniques is the best way to enhance your chance of success.