Diet apps optimize for week one.

Streak culture punishes real life.

A flu, a wedding, a sick kid, a deadline — and the user has "lost" something they spent weeks building. The shame is the off-ramp.

Shame loops drive churn.

"Good food / bad food" banners, red-pink calorie warnings, and 30-day challenges make logging feel like a confessional. Users delete the app instead of skipping a meal.

Week six is where most apps die.

Behavior change takes 66 days. The category builds for 21. Habits do not have a chance to form before the product gives up on the user.