Decision 6 of 10

Rewards, and what we will not give one for

The app gives rewards for reaching milestones. Every one of them is visible in the menu, earned or not. The list of what is deliberately left out is the part of the design that needed the research.

Written and maintained by Mattias Geniar. Last updated .

What the app does
Rewards logging, not eating less. The biggest ones count weeks in which you logged five days, and one of them is for logging a day that went over.
How much we believe it
Game elements are worth about seven hundred grams. That is small enough that no reward is worth the risks on the eating disorders page.

How much a reward is worth, which is not much

Nishi et al. (2024) is the only meta-analysis we could find that compares health apps with game elements against the same apps without them, rather than against nothing. It covers 36 trials, 49 comparisons and 10,079 people, each lasting eight weeks or more.

Everything that adding game elements to a health app is worth Body weight against the same app without them. 36 trials, 10,079 people.
no difference
Adding game elements, body weight −0.70 kg

Nishi et al. 2024, 95% CI −1.18 to −0.22, over eight weeks or more

−1.4 kg +0.4 kg
The certainty of the evidence (GRADE) was moderate to high, so the effect is real. It is also about seven hundred grams. Alongside it: −0.28 kg/m² of BMI, −1.92% body fat, and 489 more steps a day, which the authors themselves call “trivial”. This is the most the feature can do.

Why the rewards are for logging rather than for eating less

Peterson et al. (2014) followed 220 women through six months of treatment and twelve months of follow-up care. How often people logged predicted their weight change only when they logged consistently every week (moderation P = 0.004). The threshold they report is more than three days a week. In the same analysis, how complete each entry was had no effect on weight change at all (P > 0.05).

In plain terms, the research asks for “log most days, roughly.” It does not ask for “log every day, completely.” So the largest group of rewards here counts weeks in which you logged five days, and the biggest ones count total days logged, added up over time. Demanding an unbroken daily chain would be asking for more than anybody has shown to be useful.

Why almost nothing here is a streak

Cordeiro et al. (CHI 2015) surveyed 141 current and former food journalers and analysed 5,526 posts across three apps' community forums. They describe how people give up, with no streak counter involved at all — P128: “Every time I start I forget one meal or another so it becomes less accurate. Then I just forget completely.” Their conclusion is the design rule we took: “Journals cannot assume continuous and complete compliance, and should instead support the journaling habit.”

The same paper found that the feedback already feels unfair before anybody adds a game to it. P27: “I always felt guilty when I ate too much, and there wasn't that much pride when I was under my goal.”

There are four streak rewards in the app, all of them for logging and none for eating. They measure your best run ever rather than the current one. Breaking a streak costs you the next one. It cannot take away one you already have.

What we refuse to give a reward for, and why

The rule, stated as a rule Nothing in the right-hand column is a feature we have not got round to.

Gets a reward

  • Logging a day at all
  • Weeks in which you logged five days
  • Total days logged, added up over time
  • Your best run of consecutive days, ever
  • Logging a day that went over your target

Never gets a reward

  • A calorie deficit
  • A weight, or an amount lost
  • Staying under the added sugar limit
  • A “perfect” day, week or anything else
  • Eating less than your target
The calorie reward is a range with a minimum as well as a maximum: a day at 60% of your target fails it exactly as a day at 140% does. We state this as our own rule rather than as a comparison. Other trackers do reward deficits and weight lost, but the lists of their badges we could find are only in third-party copies of help pages that have since been taken down, and this page does not make claims about anybody else's product on that basis.

Nothing here is called “perfect.” Messer et al. (2021) surveyed 1,357 people. Those using a calorie app to control their weight and shape were more likely to say the app had harmed them than those using one for health reasons. The harms they named: being preoccupied with food, all-or-nothing thinking about food, anxiety about food, and purging. Plateau et al. (2018), 352 people, found the same split using different questionnaires. Why somebody tracks is the one thing that reliably separates harm from no harm, and a “perfect day” badge is all-or-nothing thinking built into the app.

And there is still no reward, streak or celebration on the added sugar limit, which is the promise the eating disorders page already makes. A limit on something with a streak attached is the design that does the most harm to the people most likely to be counting. Adding a rewards screen did not change our mind about it.

The one reward that looks odd is deliberate: you get one for logging a day that went over your target. A log with the heavy days missing is not a log. An app that is only pleasant to open when the day went well stops being told the truth.