How to use Gemini to help you diet

Updated November 2, 2026

TL;DR

Gemini can plan meals on its own, and it can read and log to a real food diary if you add Calorie Cub as a custom app at https://mcp.caloriecub.com/mcp. Google currently limits custom apps to adults in the US on personal accounts, and you connect them on the web. A Gemini skill can then hold your goals and food rules, so you don’t repeat them in every chat.

What Gemini can do for a diet without connecting anything

On its own, Gemini can draft a meal plan, write a grocery list, or suggest a lighter version of a recipe. Its calorie numbers are estimates, and it won’t keep a dependable record across days.

How accurate AI calorie estimates are ›

Can you connect Gemini to a food diary?

Yes, through Gemini’s custom apps, if you meet Google’s current requirements:

•
You’re 18 or over and in the US.
•
You use a personal Google Account. Work and school accounts aren’t supported yet.
•
Keep Activity is turned on in Gemini. Custom apps are unavailable without it.
•
You use Gemini in English.

Calorie Cub isn’t listed in Gemini’s Connected Apps. Publishing there is by Google’s selection, and we’ve only requested access, so for now you add it by address.

How to connect Calorie Cub to Gemini

1.
Open gemini.google.com on a computer. Custom apps can only be connected on the web.
2.
Select Settings, then Connected Apps. If you don’t see it, look under Personal Intelligence.
3.
Under Custom apps, add a custom app and enter https://mcp.caloriecub.com/mcp.
4.
Select Next, then sign in to Calorie Cub and approve access.
5.
In a chat, type @ and select Calorie Cub.

Once connected, it’s also available in the Gemini mobile app. Gemini asks you to confirm every write, so you’ll approve each entry before it’s logged. To stop, switch it off under Custom apps, or disconnect it in Calorie Cub’s Settings.

Google moves these menus from time to time. If a label doesn’t match, look for the option to add a custom app under Connected Apps.

Make a skill for your diet (not a Gem)

Google is replacing Gems with skills. On personal accounts, Gems become read-only on November 17, 2026, and are removed on December 17, 2026. Skills don’t need a Google AI subscription.

1.
On gemini.google.com, select Customize, then Skills.
2.
Select Create, then Create manually.
3.
Name it food-diary. Skill names use lowercase letters and hyphens.
4.
Add a short description, paste instructions like the ones below, and select Create.
5.
In a chat, type / and select the skill.

Help me keep a food diary. Before suggesting a meal, ask what I have left in my goals, or check Calorie Cub if I've attached it. Ask about the portion if I don't give one, and tell me which serving you used. I don't eat [foods]. Don't suggest skipping meals or extreme restriction, and tell me to ask a clinician about medical questions.

Already have a diet Gem? Google converts it automatically, or you can paste its instructions into a new skill. Download any knowledge files before December 17.

Prompts to try

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“@Calorie Cub What have I eaten today, and how much of my goal is left?”
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“@Calorie Cub Show my calories for the past two weeks. Which days went over?”
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“@Calorie Cub Find something at Starbucks that fits what I have left today.”
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“Plan four dinners around 600 calories using what’s usually on sale, then write the grocery list.”

With Calorie Cub Pro, Gemini can also change your diary, after you confirm:

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“@Calorie Cub Log a cup of oatmeal with blueberries for breakfast.”
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“@Calorie Cub Set my goal to 2,000 calories and 150 g of protein.”
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“@Calorie Cub I weighed 172 pounds this morning.”

If you can’t connect

Outside the US, or on a work or school account, you can still use Gemini for planning and keep your diary in the Calorie Cub app. Export your data as JSON from Settings if you want Gemini to review part of it.

Limits and privacy

Portions are still on you. “A bowl of pasta” could be 300 calories or 900, so give a size or weight when it matters, and check the serving before you confirm.

Google warns that Gemini may share information from your chat and other available sources when you use a custom app, and it doesn’t control third-party servers. What you ask, including diary data Gemini reads, also goes to Google under its privacy policy.

Food diary, not medical advice

Gemini and Calorie Cub can help you keep track and think through options, but neither is a doctor or dietitian, and an assistant can be wrong with total confidence. If you’re pregnant, have diabetes or another condition, take weight-loss medication, or have a history of disordered eating, talk to a clinician before changing how you eat.

What Calorie Cub costs

Tracking in the Calorie Cub app is free with no time limit, and the free plan 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. Your assistant’s own subscription is separate.

Questions people ask

Can Gemini track calories?

It can estimate calories in a chat, but it won’t keep a dependable running total by itself. Connected to Calorie Cub as a custom app, it can read and log to a real diary.

Should I make a Gem for calorie tracking?

Make a skill instead. Gems on personal accounts become read-only on November 17, 2026. A skill also holds instructions only, so it needs a connected tracker to keep real records.

Do I need a paid Gemini plan?

Google’s custom apps page lists age, country, account type, and Keep Activity as requirements, and doesn’t mention a subscription. Logging by chat does need Calorie Cub Pro.

Is Calorie Cub in Gemini’s Connected Apps?

Not as a listed app. It’s added as a custom app using the steps above.

Other guides

Use ChatGPT to help you diet ›ChatGPT diet plan and meal plan prompts ›Is ChatGPT accurate for calories? ›Use Claude to help you diet ›Use Grok and Grok Bot to help you diet ›AI calorie counter: photo, voice, or chat ›How logging meals by chat works ›

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