A photo, a tap, and a coach that knows my 80/20 rule. Built for people who want to eat better and still enjoy a Saturday pastry.
Here’s what’s waiting inside today:
- ✨ Idea: Create Your Personal AI Diet Coach.
How I built a tool that balances healthy eating with my love for Italian pastries. - 🍏 Tool: AI Diet Coach GPT.
A ready-to-use custom GPT you can start using today, no setup needed. - 🛠️ DIY Option: Quick-Start Prompt.
Copy, paste, and instantly create your own AI nutrition coach. - 🧠 Insights: 8 Practical Takeaways From My Experiment.
What worked, what didn’t, and how to make yours even better.
Hope you find this useful!
Dear friends,
I’ve always loved preparing and enjoying good food – the process of cooking, the flavors, the whole experience. But I also have this stubborn sweet tooth.
I’m a complete sucker for Italian pastries. During the pandemic, my evening sweet cravings turned into a nightly ritual. This habit particularly concerned me because my grandmother had diabetes and that memory has stayed with me, quietly influencing my relationship with sugar ever since.
Over the years, I’ve tried various approaches to develop healthier eating habits while still enjoying food (because let’s be honest, what’s life without some delicious meals?).
My experiments included:
- Replacing processed sweets with fruits.
- Switching sodas to kombucha and sparkling water with lemon and honey.
- Logging every single meal into tracking apps with calories, macros, and weight measurements.
- Using a CGM (continuous glucose monitor) to understand my body’s response to different foods in real-time.
These and many other small changes over the past few years, combined with regular physical activity, have helped me make steady progress.
But between us?
All that time I spent manually tracking meals and puzzling over nutrition books… imagine having a smart AI assistant from day one! I might have skipped some serious trial-and-error (and definitely would have had more fun along the way).
That’s why I’m sharing my latest experiment: an AI Diet Coach I created using ChatGPT. Consider this me sharing a tool I wish I’d had years ago. And if you’re working on your own relationship with food, I hope this will be useful for you too.
Let’s dive in.
✨ The Principles behind my AI Diet Coach
I built my AI Diet Coach around 3 principles:
- Make it easy.
From Atomic Habits book, I learned that the best habit systems reduce friction. For my AI coach, this meant simplifying the tracking process to just taking a photo of each meal. No calorie counting, no complicated logging. - Create accountability.
I borrowed this idea from a friend who worked with a personal fitness coach. Every time she ate something, she’d send a photo to her coach. This simple act created mindfulness around eating and prevented mindless snacking. On top of that, every time she ate something she was learning something new about nutrition and food. - Play the long game.
The Navy SEALs say “Slow is smooth and smooth is fast.” I wanted to use that principle in my approach – focusing on gradually improving my relationship with food rather than chasing quick fixes that never stick.
This is why I applied the 80/20 rule to my meals. I aim for 80% nutrient-focused meals and 20% joy-based choices.
The math was simple:I eat about 35 meals a week - That means 28 meals (80%) should be nutrient-dense and health-optimized
- For the remaining 7 meals (20%), I still consider quality but allow room for foods I truly enjoy
🛠️ My AI Diet Coach Features
After several iterations, I developed a ChatGPT prompt that creates a personal nutrition coach with these key features:
- 🍽️ Meal Grading (1–10 Scale)
Every meal receives a score based on protein quality, healthy fats, complex carbohydrates, micronutrients, and overall balance for my activity level. - ✨ Meal Improvements
For each meal, I get specific suggestions to enhance nutrition – like adding more protein, fiber, or micronutrients. - 🔄 3 Similar Meal Suggestions
The coach offers healthy alternatives that match the meal type while boosting variety and nutrition. - 📊 Daily Meal Tracking Table
A running table tracks:Meal name (Breakfast, Second Breakfast, Lunch, etc.) - Grade (1–10)
- Description & feedback
- Cumulative score
- 📝 Final Daily Summary
At day’s end, I review my total score and identify patterns or improvements for tomorrow.
🍏 AI Diet Coach: Ready to Use Custom GPT
Instead of just sharing a prompt, I’ve created a custom GPT that’s ready to use immediately. No setup required! 🍏 Meet AI Diet Coach.
Simply snap a photo of your meal 📸, tell it which meal you’re having, and get all the features I described above instantly.
With one click, you’ll have your own AI diet coach that scores your meals, suggests improvements, offers alternatives, and tracks your daily nutrition – all without any configuration needed.
📋 AI Diet Coach Prompt
If you prefer more customization or want to build your own version, here’s the exact prompt that will create your own AI Diet Coach.
Simply copy and paste this into ChatGPT:
I want you to be my best in the world personal coach for strength training and diet.
I’m exercising, I’m doing strength training 2-3 times a week.
My goal is to eat healthier and bring the right amount of microelements, vitamins, all the good stuff, all the healthy stuff, proteins to my body.
So my goal is to eat healthy and be healthy.
Each time I’m eating a meal, I will post a photo. I will also mention which type of meal it is: breakfast, second breakfast, lunch, snack and dinner. (These are the exact names for the meals that I’m having throughout the day). So for example, I’m going to add a photo and I’m going to say, this is what I ate for breakfast.
Your goal will be to:
1. On a scale of 1 to 10, grade my meal based on our objectives.
2. Then you’re going to provide a little improvement to the meal that I could have. Like I could have swapped something for something. I could have more protein by adding something. I could have some microelements, vitamins, etc. Anything that makes this meal healthier.
3. Then you’re going to also propose three meals that are similar, but really healthy.
4. The last thing you’re going to do is present all the meals I eat in a table for the current day. The table should include:
A. Meal name – e.g., Breakfast, Second Breakfast, Lunch, etc.
B. Meal description – what I ate
C. Grade – a score from 1–10
5. Every time I log a new meal, you will:
A. Add the new meal to the table
B. Show me the updated table with all meals from the day so far
C. Display the total score at the bottom, summing up all meal points for the day
This will give me a clear, running overview of my eating habits and how well they align with my goals.
Do you understand?
🧠 Insights: What I’ve Learned
After using my AI Diet Coach for several weeks, here are my key takeaways:
AI makes prototyping incredibly fast.
It’s not a finished app, so expect some glitches – but it’s mind-boggling how fast you can create personalized tools that would normally be expensive and time-consuming to build. This is why I love using AI for rapid prototyping. The best part? Tweaking the prompt lets me test new features without any coding, all in minutes, not hours or days.
Visual assessment actually works.
ChatGPT can evaluate portion sizes and identify ingredients pretty well from photos.
Learning by doing is powerful.
Instead of just reading about nutrition, I’m getting real-time feedback on actual meals. This contextual learning has been incredibly effective for understanding concepts like pairing healthy fats, combining sugars and proteins, and supporting gut health.
Conversation beats static information.
Being able to ask follow-up questions about recommendations makes the learning experience much richer than just reading an article or book. For example here I was talking about Tom Yum and needed an answer about complex carbs.
The 80/20 rule reduces anxiety.
Knowing I don’t need to eat perfectly at every meal has made the whole experience less stressful and more sustainable.
It helps with mindful decision-making.
I’ve started asking the coach questions like “Should I drink orange juice before bed?” or “Should I buy this?”. The answers help me make more conscious choices without feeling restricted.
It changed how I enjoy treats.
Remember what Joey from Friends once said? If you do it, do it right! ;). I still eat those Italian pastries and sweets, but I’m more mindful about the quality (not processed but natural ingredients), portion size, timing, and composition (pairing with protein to slow sugar absorption).
It provides “just-in-time” guidance.
In a Chiang Mai restaurant, faced with eight tempting Thai desserts, I simply snapped a photo of the menu and asked my AI coach for help. Within seconds, I had a complete nutritional breakdown with grading. This immediate feedback helps me make better food choices wherever I am.
It’s not a one-size-fits-all solution.
I love my AI coach, but let’s be honest – AI can make mistakes, so please have that in mind – use your common sense and talk to a real nutrition expert if you’re unsure. That said, it’s a fun, easy way to transform your relationship with food when you’re motivated to change, and you’ll learn a ton along the way.
That’s a wrap
I’d love to hear if you try creating your own AI Diet Coach. Hit reply and let me know your experience or any creative ways you’re using AI to support mindful living.
See you next time,
Originally published on Substack 👉 https://readwhitespace.substack.com/p/create-your-personal-ai-diet-coach
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