The habit · Decision 8 of 12

Tracking and eating disorders

Anybody building a calorie tracker should answer this question clearly, so this page argues against our own product.

Written and maintained by Mattias Geniar. Last updated .

What the app does
No streak on the sugar limit, no celebration for staying under a limit, no “perfect day”, and it shows what is left rather than counting upward.
How sure we are Fair , Real, but small, indirect, or thinly measured.
Surveys report associations. The trials below did not detect increased symptoms in their study populations, but do not establish safety for every user, especially people at higher risk.
What we do not have
Access to psychological support, which NICE HTG700 requires of the multidisciplinary NHS services it assesses. This is not a blanket requirement for every consumer tracker. We are not going to pretend otherwise.

What reviews and experiments found

Surveys do find a link, and that is the first section below. The pooled correlation is observational evidence; the other two results are from randomized trials.

r = 0.13 pooled correlation between weight-related self-monitoring and eating-disorder symptoms, not calorie apps alone Roth et al. (2024) · 9 studies, 13,507 people · 95% CI −0.02 to 0.28, p = 0.08
β = −0.04 effect of a month of MyFitnessPal on eating-disorder symptoms, compared with no app Hahn et al. (2021) · 200 students, p = 0.17 · screened as low risk
p ≥ 0.164 for eating-disorder questionnaire scores at twelve months; not proof of zero risk Jospe et al. (2018) · 250 adults across five groups; 53.6% reported ≥1 binge episode at baseline

The link is real in surveys

Levinson et al. (2017) surveyed 105 adults who had recently finished eating-disorder treatment. The authors say clearly that the answers look back in time and cannot show cause.

What people leaving eating-disorder treatment said about calorie apps 105 adults, surveyed after discharge. Each bar is a share of the group above it.
Had used MyFitnessPal 74%

Of all 105 respondents

Of those, said it contributed at least somewhat 73%

To their eating disorder

Of app users, said “very much” 30%

Same denominator as the 73% row, not 30% of that subgroup

0 100% of the group
Looking back, self-reported, and from a group chosen because they had had an eating disorder. It is the strongest version of the case against this kind of app. It is also the kind of evidence that cannot tell you whether the app was a cause, a symptom, or a tool somebody picked up.

Two randomized trials did not detect increased symptoms

Hahn et al. (2021) assigned 200 female students to a month of MyFitnessPal or nothing. There was no statistically significant effect on eating-disorder symptoms (β = −0.04, p = 0.17). The students had been screened as low risk, though. Jospe et al. (2018) followed 250 adults for twelve months and found no differences (all p ≥ 0.164). In that group, 53.6% had binge eating at the start.

Pooled association with weight-related self-monitoring Weight-related self-monitoring and eating-disorder symptoms: 9 studies, 13,507 adults from the general population.
no difference
Weight-related self-monitoring, pooled r = 0.13

Roth et al. 2024, 9 studies, 13,507 people, 95% CI −0.02 to 0.28

r = −0.10 r = +0.36
Drawn in grey rather than in this page's colour because the interval crosses zero: p = 0.08, not statistically significant (Roth et al., 2024). That does not mean tracking is safe. Heterogeneous studies and a large total sample do not remove confounding or establish safety in vulnerable groups.

The best summary of where things stand is Moody et al. (2025). The review found fairly consistent observational associations, but these were not replicated in the experimental evidence it reviewed. It could not establish causality or the direction of the relationship. Studies that follow people over time point both ways. In one group, tracking predicted disordered eating later. In another, behaviour like purging or over-exercising predicted tracking later (O'Loughlin et al., 2023, adjusted OR 1.7).

Two surveys reported stronger associations with harm among people tracking for weight or shape reasons. Motive is not a validated way to separate safe from unsafe use, and the design recommendations below have not been tested as protective interventions.

What the guidelines actually say

Guidance depends on the setting. Clinician-supervised food records are not equivalent to unsupervised calorie tracking. NICE NG69 includes clinician-supported food records in some forms of eating-disorder treatment. The 2023 AAP guideline notes that eating disorders and other conditions “may preclude the use of certain tools that require intensive tracking.” The clearest statement about apps like ours is NICE HTG700. It applies to specified digital multidisciplinary weight-management services considered for NHS use and requires their teams to have access to psychological support “to reduce the risk of harm, including from disordered eating.”

Snapkin has no such support, and we are not going to pretend otherwise. If you have or have had an eating disorder, please talk to a clinician before using this or any tracker.

What that changed in the app

The uncertainty above is not a reason to design as if the answer were “no harm”. It is a reason to design as if the answer were “harm”. Doing that costs a few interface decisions. Being wrong the other way costs somebody their health.

What the app does

  • Shows what is left of your day rather than counting upward
  • Rewards logging, including on a day that went over
  • Treats the calorie target as a range with a minimum as well as a maximum
  • Lets you correct any number it produced

What it will not do

  • No streak on the added sugar limit
  • No celebration for staying under a limit
  • Nothing called “perfect”
  • No reward that can be earned faster by eating less

We avoid streaks attached to dietary limits as a precaution; comparative harm between badge designs has not been established. The reasoning behind each of those choices, and the two studies on motive that decided the “perfect day” rule, are on the rewards page.