Gas station without pumps

2015 May 2

Fourth weight-loss progress report

Filed under: Uncategorized — gasstationwithoutpumps @ 08:52
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In 2015 New Year’s resolution , I said that I want to lose 10–15 pounds by June 2015. In Weight-loss progress report, Second weight-loss progress report, and Third weight-loss progress report I provided monthly updates.

April was keeping to the same diet as the previous three months: only raw fruits and vegetables for lunch on weekdays, and slightly reducing how much I ate in the evenings.  We probably had more meat this month than usual, and I did have some snack foods and desserts that I haven’t been eating in previous months, but the weight loss continued at about the same pace as before, perhaps even slightly faster:

In my target range finally!

In my target range finally!

The exponential fits to my weight loss that I tried in March turned out to have no predictive value—the straight line predictions of my weight were consistently more accurate, despite having fewer parameters to fit to the preceding data.  Daily updates to the exponential fit made it closer and closer to the straight line, so I gave up on doing them—my weight loss was not behaving like an exponential decay.

I have now lost the 20 lbs that was my most ambitious goal, and I’ll need to switch my control algorithm to try to maintain a constant weight, rather than lose a pound a week.  I don’t want to have  huge rebound in weight from ending the reducing diet, nor do I want to keep getting skinnier—I’m back in the weight range I was about 20 years ago when I was 40, and I’d like to stay there.

In coming up with a control algorithm, I need to take into consideration how much fluctuation there is in my weight (I don’t want to be changing plans all the time because of noise) as well as how fast my weight can change as a result of deliberate actions.  It looks to me like my weight fluctuates about ±2 lbs around the trend line, so a target range that is 5lbs wide is probably going to be as tight as I can control my weight.

I’m thinking of using a two-state control algorithm with hysteresis and time delay:

  • Normal diet: If my weight is ≤ 156 lbs for 2 days in a row, I’ll eat lunches with a fair number of calories (from the taco truck or sandwiches).
  • Reducing diet: If my weight is ≥ 158 lbs for 2 days in a row, I’ll use my current reducing diet (only raw fruit or vegetable for lunch).

I may add a couple more transition points at the edges of the range (extra desserts if I fall below 155 pounds, more attention to eating less in the evening if I go over 160lbs), but I’m hopeful that the control algorithm won’t hit those boundaries very often. If I see a periodic fluctuation in my weight, I may switch to faster control (not weight for two days above the high threshold or below the low threshold).

Right now I’m still on the reducing diet, but I may hit the first transition point in the next week and start eating lunches with more calories again.

 

 

10 Comments »

  1. Congratulations. Very admirable.
    Did it help to have posted your weight loss goal up front, and to post progress reports as well?
    Great job!

    Comment by Sally — 2015 May 2 @ 09:03 | Reply

    • I don’t know whether it helped or not (no controls on the experiment). This is the first time I’ve made a sustained effort to lose weight, so I did look up what were considered best practices before I started. I saw claims that having a group of people to whom one reported goals and progress helped, so I decided to use my blog for that. Whether it actually helped or not is irrelevant to me, as long as whatever I did worked, which it seems to have done.

      Comment by gasstationwithoutpumps — 2015 May 2 @ 09:07 | Reply

  2. I would suggest that if you thought about the blog post and put down food you otherwise would have eaten, then you can say you were influenced by the posting requirement – controls or no controls. If you didn’t think of such things, you did it without conscious influence from the blog posting. Was there something subconscious? Unknown.

    I hope you’ll report on keeping it off — that’s supposed to be hard to do as well. My mother’s weight went up and down – a life long battle. Now in her old age she’s given up on her weight, satisfied to declare that had she not worked on it over the years, today she’d be even more overweight.

    Comment by Sally — 2015 May 2 @ 17:54 | Reply

    • I don’t think that the blog ever caused me to put down food or change my decisions about eating. It may have made me more diligent about recording my weight every day and plotting the progress, which in turn may have given me incentive to continue during the week-long plateaus in my weight.

      I do plan to report on how well the weight-maintenance algorithm works—at least for a few months, and possibly longer.

      Comment by gasstationwithoutpumps — 2015 May 3 @ 11:17 | Reply

  3. I notice that your maintenance algorithm seems to focus on caloric input rather than energy expenditure. I can imagine you might design an algorithm that includes a consistent healthy diet with adjustments to your activity level. Or, of course, you could use both methods, e.g., planning to increase activity level if weight rises, but reducing caloric input if that doesn’t happen. I ask this because, while I don’t recall if you ever stated your motivation for weight loss, presumably at least part of it is about health. And I think focusing on healthy eating all the time and maintaining physical activity probably does more to maintain health than maintaining a particular weight.

    Comment by Ron Goodman — 2015 May 3 @ 10:41 | Reply

    • My exercise level has been fairly constant over the past couple of decades, and I’m unlikely to be able to increase my exercise level much, both because I don’t have time and because I dislike exercise for its own sake. I rely almost entirely on bicycling for transportation to provide exercise. For the past year, I’ve been averaging a pretty steady 4 miles of bicycling a day, which is mostly my 6-mile roundtrip commute to my office at UCSC. With a steady 4% climb in the morning and a –4% coast downhill in the evening, this gives me 30–40 minutes of moderate exercise 5 days a week. This is within the range that is considered good for maintaining health, though not enough to improve athletic performance (which is not of any importance to me).

      I have been doing a few crunches every day to try to trim my waistline by improving muscle tone, but I don’t know how long I’ll keep that up—other exercise regimes, other than bicycle commuting, have rarely lasted more than 4 months.

      My motivation for my weight loss is mixed: partly health, partly cosmetic, partly just to see if I could do it. I’ve always maintained physical activity and paid attention to healthy eating, but that did not stop a 1 lb./year upward creep in my weight. This diet was an attempt to reset that by 20 years. Maintaining a constant weight (within a narrow range) is a way of paying a bit closer attention to healthy eating, without having to obsess about it at every meal.

      Comment by gasstationwithoutpumps — 2015 May 3 @ 11:14 | Reply

  4. Fantastic! Keep up the effort.

    I like your point about a “reset”. That was my goal as well.

    Comment by CCPhysicist — 2015 May 3 @ 22:09 | Reply

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