Fasting, with the reason attached.
16:8, 18:6, 20:4, OMAD or a window you set yourself, with a live timer on your lock screen, a plain explanation of what is happening at each stage, and a coach that will tell you to skip it if that is what your logs point to.
Premium · Live Activity on the iPhone lock screen
A timer is the easy part.
Any app can count hours. The useful parts are knowing what the hours are doing, and being told plainly when fasting is not the thing that will help you. It is also not for everyone: Varady and colleagues advise against it in pregnancy, while breastfeeding and with a history of an eating disorder in Nature Reviews Endocrinology (2022), and Albosta and Bakke note in Clinical Diabetes and Endocrinology (2021) that anyone taking insulin or a sulfonylurea needs close supervision so that fasting does not cause hypoglycaemia.
The usual windows, or one of your own
16:8, 18:6, 20:4 and OMAD are one tap each. If none of them fit the shape of your day. Shift work, a family dinner you are not going to skip. Set your own window and Loopa tracks that instead of nagging you toward a standard one.
Longer fasts are tracked too. 24 hours, 48 hours, 3 days and 7 days as presets, or a duration you set, up to 40 days. Anything of 48 hours or more shows a health notice first, with a clear statement of when to stop and seek care. Extended fasting is not a beginner’s tool and it is not a target to work toward. Prolonged fasting belongs under clinical supervision: the largest chart review of medically supervised water-only fasting, by Finnell and colleagues in BMC Complementary and Alternative Medicine (2018), reports its safety finding as conditional on the medical setting, and the risk on the way out is real, the National Library of Medicine’s Refeeding Syndrome describes fluid and electrolyte shifts on refeeding that “can be fatal if inappropriately managed”. Loopa will keep the clock; the decision belongs with a clinician.
Premium- 16:8, 18:6, 20:4 and OMAD preset
- 24 hours, 48 hours, 3 days and 7 days for longer fasts
- Or set your own, up to 40 days
- A health notice at 48 hours and over, every time
- Change protocol whenever the week changes
On your lock screen, not buried in an app
An open window runs as a Live Activity on iPhone, so the remaining time is on the lock screen and in the Dynamic Island. You are not opening an app to find out how long is left, which is the moment most people give up and eat.
Premium- Live Activity on the iPhone lock screen
- Home-screen widgets on both platforms
- Start, pause and end without opening the app
What is actually happening, hour by hour
Each stage of the window comes with a plain explanation of what the body is doing and, just as usefully, what it is not. Anton and colleagues put the crossover from stored glycogen to fat somewhere between roughly 12 and 36 hours in Obesity (2018), depending on where you started and how active you are, and the National Institute on Aging says in Calorie Restriction and Fasting Diets: What Do We Know? that there is not yet enough evidence to recommend any particular fasting pattern to the public. That is what the explanations say. The point is that you know why you are doing this at hour fourteen.
Premium- Stage-by-stage explanation as the window runs
- Written plainly, without overclaiming
- Streaks, without a punishment for breaking one
It will tell you not to
Ask the coach whether a protocol suits you and it reads your actual history first. What you eat, how you sleep, what your weight has been doing. If the answer is that fasting is not your problem, or that your logs suggest it would make things worse, that is what it says. It is not there to sell you the feature you are already paying for.
Premium- Reads your own logs before answering
- Will recommend against fasting when your logs point that way
- General guidance only. Medical questions go to your clinician
More on how Loopa works
Frequently Asked Questions
What people ask before they start a window.
Which fasting protocols does Loopa support?
16:8, 18:6, 20:4 and OMAD as one-tap presets, plus 24 hours, 48 hours, 3 days and 7 days for longer fasts, and any custom duration up to 40 days. You can change protocol whenever your week changes.
Can Loopa track a fast longer than 48 hours?
Yes, up to 40 days. Any fast of 48 hours or longer shows a health notice before it starts saying when to stop and seek care, and you acknowledge it each time rather than once. Loopa keeps a hydration and electrolyte reminder on screen while a long fast runs, and ending the fast stays one tap. Extended fasting carries real risk and should be undertaken only under the care of a clinician, the National Library of Medicine’s Refeeding Syndrome describes fluid and electrolyte shifts on refeeding that “can be fatal if inappropriately managed”. Loopa is a general wellness product and does not give medical advice.
Is fasting free in Loopa?
No, fasting is part of Premium. Food, weight and water logging are the free tier. For what it is worth, fasting is a paid feature in the other trackers we checked as well.
Does the timer show on my lock screen?
On iPhone, yes, an open window runs as a Live Activity, so the remaining time appears on the lock screen and in the Dynamic Island. Both platforms also have home-screen widgets.
Will Loopa tell me if fasting is a bad idea for me?
It will give you a straight read. Ask the coach and it looks at your own logs first, and if the answer is that fasting is not the thing that will help, or that your history suggests it would make matters worse, it says so rather than encouraging you into a feature you are paying for. For anything medical it points you at your clinician, because that is a boundary it does not cross.
Do I lose my streak if I break a fast?
The streak resets, but nothing scolds you and nothing else is taken away. Loopa is deliberately built without the all-or-nothing pressure that makes people quit an app after one bad week.
Can I still log food during a fast?
Yes, and you should, the fasting window and the food log are the same timeline, so what you eat when the window opens is counted against the same daily targets as any other day.
Start a window tonight.
Or start with the free tier and just log your food for a week first. That is usually the more useful experiment.