Adherence via Simplicity

We saw in the previous blog post that calorie reduction works. You'll lose weight if you eat less -- i.e., if you eat few enough calories. The problem seems to be adherence. That is, people drift off their diets and begin eating too much and regain weight.

I stopped losing weight because I stopped counting calories and starting eating more. I stopped counting calories because it was too hard. It wasn't hard to do at first. It was even interesting to learn a little about the foods I was eating. When that novelty wore off however, I was faced with these difficulties:

  • It takes time to look foods up in a calorie database, even if that database is in a well-designed App.
  • It is difficult to know the ingredients and amounts of ingredients in restaurant food. (Ex., How many tbsp. of butter are on my bagel? What's in that delicious sauce on my fish?)
  • It is difficult to estimate the size of some foods (ex., Is that a medium apple or a large apple? How many ounces of chicken are on my plate?)
    • There can be many ingredients in home-cooked food that, ideally, should be measured individually and then looked up.

All of these things, for me, are quite tedious and distracting and result in fatigue and frustration. Even though the fatigue and frustration are mild, over time they're discouraging enough to make me quit.

So I hypothesize that I’ll persist in calorie counting/reduction if the process is simple enough.

Below I discuss the three simplifications made by Pertinacity in an attempt to improve adherence: the design of a calorie proxy, the design of a calorie limit, and the elimination of a weight-loss goal (and thus a "maintenance" mode).

Calorie Proxy

I want a method of measuring calorie intake that doesn't require a database search, works with any food (home-cooked, packaged, prepared), and works anywhere (home, work, vacation).

To simplify calorie intake measurement I estimate calories by proxy -- or "signal" in statistical terms. The signal is defined in the Pertinacity Instructions:

  • Imagine squashing the food item.
  • Make a fist. Estimate how many fists would be the same size as the squashed food item.
  • Exclude drinks known to have zero calories (water, diet soda, tea, black coffee, etc.), but include other drinks like smoothies, alcohol, regular soda, milk, juice, etc.

This solves the "any food" and "anywhere" problems. You measure an entree at a restaurant the same way you measure a bag of chips or a sandwich you make at home. Also, your "measuring device" -- your fist -- is always with you. You won't need to use a diet scale, measuring cups, etc. to get the job done. Using a fist to help estimate food volume is a technique borrowed from Portion Control).

[The next step is to verify that this proxy gives a good -- or, at least, good enough -- estimate of calories to be useful. After all, different foods have different calorie densities (calories / unit volume) so treating them all equally will result sometimes in overestimation and sometimes in underestimation. It seems fair to guess that these fist estimates won't be as precise as database lookups. How much less precise are they? How precise are database lookups in the first place? And what about accuracy? We'll explore these questions in future posts.]

Calorie Limit

Since we're estimating calorie intake by proxy we can't directly make use of a reference model like Dietary Reference Intakes . (Weight-loss systems often start with that number and compute a daily calorie limit by incorporating other information.) Instead we'll develop a direct proxy limit, i.e., a limit on the number of fist-sized portions we may eat today.

A simple way to do this is to ask, "How many fist-size portions do you usually eat?" Pertinacity assumes this is enough to maintain your weight and then asks you to eat a little less. The limit is determined by taking the average of the past two weeks of your daily counts of fist-sized portions (shown in the History Editor ) and subtracting a little bit.

The assumptions in computing a limit this way are:

  • You will eat foods today that are similar to foods you've been eating for the past two weeks.
  • You will engage in physical activity today that is similar to the physical activity you've been engaging in for the past two weeks.
  • Your basal metabolic rate today will be similar to what it has been over the past two weeks.

Since the average is taken over the past two weeks looking back from the current day, if you do start a new exercise program or change your diet dramatically Pertinacity will automatically adapt its recommendations as data accumulates. You just keep counting fist-sized portions as usual.

Goals and Maintenance

A typical first step in a diet program that uses calorie counting is to define a goal. The goal is specified as something like "Lose P pounds in W weeks." After you reach your goal you switch from a weight-losing diet to a maintenance diet.

How much weight can someone lose and in what period of time? I don't know.

Should you set a more achievable (less aggressive) goal so that you won't be discouraged? No, it doesn't seem to matter. One study, Are smaller weight losses or more achievable weight loss goals better in the long term for obese patients? examines this question and concludes "...these results do not support the hypothesis that obese patients should be encouraged to set lower weight-loss goals". Another study, Are Unrealistic Weight Loss Goals Associated with Outcomes for Overweight Women? concludes "Results suggest that lack of realism in weight loss goals is not important enough to justify counseling people to accept lower weight loss goals when trying to lose weight."

So if we don't know how quickly we can (or should) lose weight and it seems that progress in weight loss is the same for reasonable goals as for unreasonable goals, maybe we should just do away with goals. Maybe a goal isn't an important factor in designing a weight-loss strategy.

Doing away with the goal-setting stage affords us more simplification. It means that when you start using Pertinacity you don't have to figure out the answer to the question about a goal. It also means that there's no separate "maintenance mode". You do the same thing everyday forever. There's less to learn and less to do.


I hypothesized that if I could make calorie counting simple enough I'd keep at it -- i.e., I'd show greater adherence. By eliminating maintenance and an explicit weight-loss goal and by switching to a calorie proxy my weight-control strategy has become very simple: I estimate the number fist-sized portions I eat and tap '+' to count them with Pertinacity.

Is it effective? I'm very optimistic. As of this writing I've been using Pertinacity for a little over eight months and have steadily lost weight -- 12 pounds -- without weight regain and without fatigue or frustration.