AI fitness app privacy: what gets sent, and to whom
An AI fitness coach sends your meals, photos and words to an AI company. What a straight app tells you first: what is sent, who receives it, and how to take it back.
An AI fitness coach sends what you tell it to an AI company, because the coach is a language model and the model runs on someone else’s servers. The question worth asking is not whether it sends anything. It is whether the app tells you what is sent, names who receives it, and asks before the first word leaves the phone. Apple’s review guidelines now require exactly that of every app in its store. Below: what that disclosure should say, what GreekBody’s says word for word, and five checks to run on any app before you tell it what you ate.
Why every AI coach sends something
A coach that answers “how much steak fits tonight” has to read what you ate at noon. A coach that reads a photo of your plate has to receive the photo. There is no version of this where the model works blind, and few fitness apps run their own large model. The work goes to OpenAI, Google, Anthropic or a handful of others, often through a router in between.
That is not a scandal. It is the product. The failure is hiding it: a paragraph deep in a privacy policy nobody opens, a vague “trusted partners”, a toggle that turns off the thing you paid for. A man logging his body, his meals and his photos is owed the plain version, up front.
What Apple now requires
Apple’s App Review Guidelines, section 5.1.2(i), say it directly: an app must clearly disclose where personal data will be shared with third parties, “including with third-party AI”, and obtain explicit permission before doing so. On a screen, before the sharing starts. Not implied by signing up.
Section 1.4.1 of the same guidelines asks apps to disclose the data and methodology behind health measurements. App Review applied it to GreekBody’s calorie and protein targets: the formula and the paper behind each, somewhere a man can find them.
Neither rule is exotic. Both are what a straight coach would do without being told.
What GreekBody’s screen says
Before the plan is built, one screen, titled “Achilles runs on AI”, says three things and asks once.
What is sent. “Your answers here, the meals and photos you log, what you say to the coach, and your check-in photos only when you ask for a plan. Never your name, email or Apple ID.”
Who gets it. “OpenAI and Google, through OpenRouter, to run the coach, read food photos and turn your voice into text. Google Search sees a food’s name when the coach cannot identify it.”
Why. “That is what the coach is. Without it there is no plan and no coaching.”
Then one button: “I agree, build my plan”. The same three blocks sit in Settings under “Your data and AI”, with the date you agreed. The privacy policy names the same companies in the same terms, and states that under the API terms used, the content sent is not used to train the models.
There is no switch to take it back and keep the coach, and the screen says so. Withdrawing is closing the account, under Settings > Account, and that removes everything: the training history, the food logs, the measurements, the photos. A toggle that quietly kept the coach running on less data would be a nicer screen and a less honest one.
The numbers need sources too
The second half of the same standard is the targets. GreekBody sets a resting burn, a protein target, fibre, a rate of fat loss, a body-fat estimate, a muscle target, a step goal and a progression rule. Each one has its paper one tap away, under Settings > Sources: Mifflin-St Jeor for the resting burn, Morton 2018 and the ISSN position stand for protein, the Navy tape equations for body fat, the ACSM’s 2009 position stand for progression.
A coach that tells you to eat 117 g of protein should be able to say why 117. If it cannot, the number is its opinion.
Five checks for any AI fitness app
Run these before the first log, on any app, ours included.
- Does it name the AI company? “Our AI partners” is not an answer. OpenAI, Google, Anthropic, and any router in between, by name.
- Does it say what is sent, and what is not? Meals, photos, voice, messages, check-in photos. And the negative: your name, your email, your account ID.
- Did it ask before sending? A screen with a button, before your first message. Not a clause you accepted by creating the account.
- Can you leave from inside the app? Account deletion in Settings, and a plain statement of what it removes.
- Are its numbers cited? Calories, protein, body fat, progression. A formula and a paper, not “our proprietary algorithm”.
Five yeses is an app treating you as an adult. Anything less, decide with that in view.
The short version
Every AI coach sends your words somewhere; the model is the coach. What separates a straight app from the rest is that it names who receives them, says what is sent and what never is, asks on a screen before the first message, lets you delete everything from Settings, and cites the numbers it gives you. GreekBody does all five. Download it on the App Store. For what the coach does once it has your record, see AI fitness coach apps: what the chat changes.
Frequently asked questions
Does an AI fitness app send my data to OpenAI or Google?
If the coach is a language model, almost certainly: few fitness apps run their own. GreekBody sends your coach messages, the meals and food photos you log, your voice for transcription, and your check-in photos only when you ask for a plan, to OpenAI and Google through OpenRouter. It never sends your name, email or Apple ID, and it says all of this on one screen before anything leaves the phone.
Is my fitness data used to train AI models?
It depends on the terms the app signed with the AI company, which is why the app should name the company. GreekBody's privacy policy states that under the API terms it uses, the content it sends is not used to train the models. An app that will not name its AI vendor cannot answer this question for you.
Can I use an AI coach without sharing data with an AI company?
Not in any honest sense. The coach is the model; a coach that does not see your meals cannot answer from them. What you should get instead is the choice made plainly, before the first message, and a way out: in GreekBody, withdrawing is deleting the account from Settings, which removes everything.
How do I delete my data from an AI fitness app?
Look for account deletion inside the app, not an email address in a policy. Apple requires apps that create accounts to offer deletion in the app. GreekBody's is under Settings > Account, and it removes your training history, food logs, measurements and stored photos.
