Log meal nutrition from LINE food photos to Google Sheets with Gemini AI

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Last update

Last update 5 hours ago

Who is this for

Health-conscious individuals, people on a diet, and anyone who wants to track daily nutrition without manual data entry. Designed especially for LINE users (Japan, Taiwan, Thailand, etc.) who want an effortless way to monitor calories and macronutrients from meal photos.

What this workflow does

Send a meal photo to a LINE bot and Gemini 1.5 Flash automatically identifies the food and estimates calories, protein, fat, and carbohydrates. Each meal is logged to Google Sheets with a timestamp and user ID. The workflow calculates the running daily calorie total and warns when the personal limit is exceeded. Every Monday morning, a weekly nutrition summary with AI-generated advice is pushed via LINE automatically.

How to set up

Create a LINE Messaging API channel and copy the Channel Access Token
Copy your LINE User ID for weekly Push messages
Set up a Google Sheet with columns: Timestamp, LINE_UID, Food_Name, Meal_Type, Calories, Protein, Fat, Carbs, Confidence
Get a Google Gemini API key (free tier available)
Configure CALORIE_LIMIT (default 2000) and LINE_USER_ID in the Set Config Fields node
Register the n8n Webhook URL in LINE Developer Console

Requirements

LINE Messaging API account (free tier)
Google Sheets (any Google account)
Google Gemini API key (free tier available)

How to customize

Adjust CALORIE_LIMIT in the Set Config Fields node for different dietary goals. Add a Slack notification node to share weekly reports with a fitness accountability group. Modify the Gemini prompt to track additional nutrients like fiber or sodium.

Node List

#	Node Name	Type	Role
1	Set Config Fields	Set	Centralizes LINE token, Sheet ID, calorie limit, and user ID
2	When LINE Event Received	Webhook	Receives LINE Webhook (POST)
3	If Image Message	If	Branches on image vs text message
4	If Report Command	If	Checks whether text is a report command
5	Send Help Reply via LINE	HTTP Request	Sends usage guide as reply
6	Fetch LINE Image Data	HTTP Request	Downloads image from LINE Content API
7	Encode Image to Base64	Code	Converts image binary to Base64 string
8	Gemini Food Analysis Config	Gemini Chat Model	Gemini 1.5 Flash model for food analysis
9	Process Food Analysis	LLM Chain	Estimates nutrition info from meal image as JSON
10	Extract Nutrition Data	Code	Extracts and parses JSON from Gemini response
11	Append Meal to Sheets	Google Sheets	Appends nutrition data to spreadsheet
12	Read Today's Total from Sheets	Google Sheets	Retrieves all records for today
13	Compute Daily Calorie Total	Code	Calculates total calories for the day
14	If Over Calorie Limit	If	Checks whether daily limit is exceeded
15	Send Calorie Warning via LINE	HTTP Request	Sends calorie warning reply via LINE
16	Send Nutrition Info via LINE	HTTP Request	Sends nutrition info and daily total via LINE
17	Weekly 9AM Schedule	Schedule Trigger	Triggers weekly report every Monday at 9 AM JST
18	Read Weekly Data from Sheets	Google Sheets	Retrieves records from the past 7 days
19	Summarize Weekly Stats	Code	Aggregates weekly totals, averages, and peak day
20	Gemini Weekly Report Config	Gemini Chat Model	Gemini 1.5 Flash model for weekly comment
21	Create Weekly Comment with LLM	LLM Chain	Generates personalized nutrition advice
22	Deliver Weekly Report via LINE	HTTP Request	Sends weekly report via LINE Push
23	Send Webhook Response OK	Respond to Webhook	Returns HTTP 200 to Webhook

Total: 23 nodes (+ 9 Sticky Notes)

Sticky Note Compliance

#	Sticky Note Title	Color	Role
1	Main Sticky Note (Overview)	Yellow	Workflow overview, How it works, Setup steps, Customization
2	Set configuration fields	White	Covers configuration setup
3	Receive and verify message type	White	Covers LINE webhook and message type checks
4	Download and convert image	White	Covers image fetch and Base64 encoding
5	Analyze image and parse data	White	Covers Gemini analysis and data parsing
6	Log and calculate nutrition	White	Covers meal logging and daily total calculation
7	Notify via LINE based on calorie	White	Covers calorie warning and nutrition info LINE replies
8	Weekly report scheduling and stats	White	Covers schedule trigger and weekly aggregation
9	Respond to LINE webhook	White	Covers webhook response

All sticky notes use H2 headings (## ) and follow n8n public guidelines.

Setup Guide

1. Create a LINE Messaging API channel

Log in to LINE Developers
Create a new provider and a Messaging API channel
Issue a long-lived Channel Access Token and copy it
Copy your User ID from the channel basic settings

2. Prepare Google Sheets

Create a new spreadsheet
Add the following headers in row 1:

Timestamp | LINE_UID | Food_Name | Meal_Type | Calories | Protein | Fat | Carbs | Confidence

Copy the spreadsheet ID from the URL (between /d/ and /edit)

3. Get a Google Gemini API key

Go to Google AI Studio
Create an API key (free tier available)
Register it as a Google PaLM API credential in n8n

4. Configure the n8n workflow

Import the workflow JSON into n8n
Open Set Config Fields and enter:
- LINE_CHANNEL_ACCESS_TOKEN
- GOOGLE_SHEET_ID
- CALORIE_LIMIT (default: 2000)
- LINE_USER_ID
Set up Google Sheets OAuth2 and Google PaLM API credentials

5. Register the Webhook URL

Activate the workflow in n8n
Copy the Webhook URL
Paste it into LINE Developers Console → Messaging API settings
Enable Webhook and verify the connection

6. Test

Send a meal photo to your LINE bot → confirm nutrition info is returned
Send "report" as text → confirm weekly summary is returned
Send other text → confirm help message is returned