A calorie tracker for ChatGPT and Claude: log meals by saying what you ate

Updated October 31, 2026

TL;DR

An AI assistant can only keep a real food diary when it is connected to a calorie tracker through MCP. Otherwise it guesses a number and forgets it. Calorie Cub is that tracker: add https://mcp.caloriecub.com/mcp to ChatGPT or Claude, say what you ate, and it logs the right food from a verified catalog to a diary you can also open in the app.

What a ChatGPT calorie tracker actually does

Ask ChatGPT how many calories are in your lunch and it will give you a number. It won’t save that number anywhere you can rely on, it may give you a different one tomorrow, and it doesn’t know what you ate yesterday.

A connected tracker fixes that. MCP (Model Context Protocol) is the open standard ChatGPT and Claude use to work with other apps. When a calorie tracker runs an MCP server, the assistant can search its food database, write entries to your diary, and read your totals back. You talk to the assistant; the tracker keeps the record.

How logging by chat works

1.
Connect once. Add the Calorie Cub address to ChatGPT or Claude, sign in, and approve what the assistant is allowed to do.
2.
Say what you ate, the way you’d tell a friend: “two scrambled eggs and a banana for breakfast.”
3.
The assistant looks each food up in the Calorie Cub catalog, picks a serving, and logs it. Calorie Cub calculates the nutrition itself, so the numbers come from the food record, not from the model’s memory.
4.
Check it anywhere. The entry is in your diary right away, in the chat and in the Calorie Cub app on the web and iPhone.

Things you can say

Once Calorie Cub is connected, plain sentences like these work:

•
“Log a Chick-fil-A Spicy Chicken Sandwich for lunch.” (450 calories and 28 g of protein, from Chick-fil-A’s own nutrition page.)
•
“Add a cup of oatmeal with blueberries to breakfast.”
•
“Copy yesterday’s breakfast to today.”
•
“How much protein do I have left today?”
•
“Make that lunch half a serving.”
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“Delete the coffee I logged this morning.”
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“Show my calories for the last two weeks.”
•
“Save my chili as a recipe. It makes six servings.”
•
“Set my goal to 2,000 calories and 150 g of protein.”
•
“I weighed 172 pounds this morning.”

Why the food data matters more than the AI

Language models are good at understanding “a grande iced latte with oat milk.” They are not a nutrition database, and the same meal described twice can get two different estimates.

Calorie Cub keeps those jobs apart. The assistant works out what you meant. The numbers come from a catalog built from USDA data and restaurants’ own published nutrition guides. Every food is labeled official, reviewed, or estimated, so you can see how far to trust it.

Restaurant meals are where this pays off. The catalog has the menus of more than 25 of the biggest US chains, from McDonald’s, Starbucks, and Chick-fil-A to Olive Garden, Chili’s, and Applebee’s, item by item and size by size.

Browse restaurant nutrition facts ›

If a food isn’t in the catalog, the assistant can save it as your own custom food, labeled estimated, and you can correct it later.

How to connect Calorie Cub to ChatGPT

1.
In ChatGPT on the web, open Plugins from the sidebar.
2.
Select Add, then Add custom MCP server.
3.
Name it Calorie Cub, enter https://mcp.caloriecub.com/mcp as the Server URL, and leave Authentication on OAuth.
4.
Confirm the custom server notice, create it, then sign in to Calorie Cub with Google and approve access.
5.
Start a new chat, add Calorie Cub from the tools menu, and tell it what you ate.

Custom MCP servers aren’t available on every ChatGPT plan, and work accounts may need an admin to allow them. ChatGPT also renames these menus from time to time; if a label doesn’t match, look for the option to add a server by URL.

How to connect Calorie Cub to Claude

1.
On claude.ai or in the Claude desktop app, open Settings, then Connectors.
2.
Choose Add custom connector and paste https://mcp.caloriecub.com/mcp.
3.
Sign in to Calorie Cub and approve access.
4.
Start a new chat and tell Claude what you ate.

Connectors follow your Claude account, so the Claude mobile app gets Calorie Cub too. In Claude Code, one command does it:

claude mcp add --transport http calorie-cub https://mcp.caloriecub.com/mcp

Any other app that supports remote MCP servers can use the same address and sign-in. For scripts and clients without OAuth, create a personal API key in Settings.

A connected tracker vs. pasting your diary into ChatGPT

Some people export a week of data from their tracker and paste it into a chat. That works for a one-time review, but the assistant can’t add anything back, the export is out of date by your next meal, and a long paste crowds out the rest of the conversation.

With a connected tracker, the assistant reads only what it needs, like today’s entries or a two-week summary, and writes changes straight to your diary.

What logging by chat is still bad at

Portions. “A bowl of pasta” can be 300 calories or 900. When it matters, give a size or a weight, and check the serving the assistant picked.

Home cooking. A lasagna you made has no label. Save it once as a recipe with its ingredients, and every serving after that is one sentence.

Repeat foods. Tapping a favorite in the app is still faster than typing a sentence. Use whichever is quicker at the moment; both end up in the same diary.

Privacy and control

Each assistant gets only the permissions you approve: reading your diary, writing entries, editing your foods and recipes, or changing your goals. Disconnect any of them in Settings and it loses access immediately.

Calorie Cub doesn’t sell data or show ads. You can export everything as JSON or delete your account in Settings.

Whatever you ask an assistant about is also sent to the company behind it, OpenAI or Anthropic, under their privacy policy.

What it costs

Tracking in the Calorie Cub app is free with no time limit, including the food catalog, restaurant menus, recipes, favorites, and export. The free plan also lets one assistant read your diary.

Logging, editing, and setting goals by chat is part of Pro: $6.99 a month, or $39.99 a year with a 3-day free trial.

Questions people ask

Can ChatGPT track my calories without an app?

It can estimate calories in a conversation, but it won’t keep a dependable diary or running totals across days. For that it has to be connected to a tracker.

Can I log by voice?

Yes. The Calorie Cub app has Log by voice: say what you ate, confirm the matches, and add them. Assistant voice modes that support connected tools can work too, though support varies by app.

How accurate is it?

As accurate as the food record and the portion. Restaurant and packaged foods come from published nutrition and are labeled official. Generic foods come from USDA data. Anything estimated says so.

Will a dropped connection log a meal twice?

No. Every write carries a one-time key, so a retried request can’t create a second entry.

Which assistants work with Calorie Cub?

Claude and ChatGPT, plus any app that supports remote MCP servers, such as Claude Code.

Try Calorie Cub free

How Calorie Cub works