Zenday App vs MyFitnessPal: calorie counting was built for a different problem

Why does a GLP-1 need its own app at all?

Because the medication changes what the problem is. Appetite drops sharply, often unevenly across the dose cycle, and the old skill — eating less than you want — stops being the thing you need help with. Three new problems take its place: getting enough protein into a much smaller appetite, protecting muscle during rapid loss, and getting through the side-effect weeks that follow every dose increase.

Side effects are the single most common reason people stop treatment. That's the failure mode a GLP-1 companion exists to prevent, and it's the reason a general-purpose tracker struggles here no matter how good it is at its own job.

Zenday App was founded in 2025 by Emily Carter, who was taking a GLP-1 herself, and built with a doctor-led team. It now reports more than a million users. Its three pillars are dose-linked daily guidance, side-effect management, and privacy — it runs in a browser, so there's no app icon on your phone and no app-store purchase trail.

Why doesn't calorie counting fit GLP-1 treatment?

Every calorie tracker is built on one assumption: your problem is eating more than you intend, so the app's job is to make you aware of it. GLP-1 medication removes that problem pharmacologically. What's left is the opposite challenge — many people struggle to eat enough, and particularly to reach protein targets, when appetite has largely gone.

A tracker that congratulates you for being under your calorie goal is giving you the wrong feedback on a GLP-1. Being 700 calories under target with 35g of protein is not a good day; it's a day you lost muscle. Zenday App is built to say that, and MyFitnessPal is not built to notice it.

How accurate is MyFitnessPal's food data?

Worth knowing, because protein is now the number that matters most. A 2025 study in the Journal of Human Nutrition and Dietetics had two raters enter the same 43 three-day food records into MyFitnessPal and Cronometer. MyFitnessPal showed poor validity for total energy, carbohydrate, protein, cholesterol, sugar and fibre, and the two raters produced inconsistent results for sodium and sugar.

The cause is architectural: MyFitnessPal's database is largely user-submitted and unverified, so near-duplicate entries disagree and choosing between them is a judgement call. We covered this in detail in our Cronometer vs MyFitnessPal comparison.

If you stay on MyFitnessPal, use only entries with the verified tick. It roughly doubles logging time and removes most of the error.

What MyFitnessPal is genuinely best at

No app in this comparison is bad, and pretending otherwise would make this page less useful. Here's where MyFitnessPal leads:

• The largest food database in the category — it will find almost any restaurant item
• Familiarity: if you've logged in it for years, the muscle memory is worth real money
• Recipe import and a large community
• Integrations with almost every fitness device on the market

The cost framing that actually matters

GLP-1 medication commonly runs $500–$1,000 a month. Against that, the difference between two companion apps is a rounding error — usually less than two days of prescription. The question worth asking isn't which app is cheaper. It's which one makes the expensive thing work harder, and which one keeps you on treatment through the weeks when most people stop.