Diet Claude is what I've started calling a specific setup: turn Claude, Anthropic's AI assistant, into a standing meal-planning and macro-tracking coach instead of paying for a separate diet app. You build it once, inside a single Claude Project with the right instructions, and it lives in a chat you already have open every day.
It isn't an official Anthropic product — there's no "Diet Claude" button anywhere in the app. It's a configuration: a Project with your stats and goals loaded in, plus a habit of asking Claude for meal plans, macro math, and food-photo estimates instead of switching apps. I set this up on my own Claude account over two weeks to see whether it actually replaced anything I was paying for, and where it fell short.
Short answer: Diet Claude is a do-it-yourself setup, not a built-in feature: create a Claude Project, load it with your stats and a dietitian-style instruction set, then ask Claude for meal plans, macro breakdowns, and food-photo estimates in plain chat. It runs on Claude's Free plan for $0, or Pro at $17–$20/month for more usage. Photo-based calorie estimates carry real error, so treat them as a rough guide, not a lab number.
What you'll need
Any Claude account works — Free, Pro, Max, Team, or Enterprise — because Projects and memory are available on all of them. You don't need Claude Code or the desktop app; claude.ai in a browser or the mobile app is enough. Before you start, have your basics ready: age, sex, height, current weight, activity level, and a goal (maintain, lose, or gain, and roughly how fast). If you have any allergies, medical conditions, or foods you won't eat, write those down too — you'll want to hand them to Claude on day one, not mention them after it's already suggested shellfish. Five minutes of prep here saves you from re-explaining yourself in every chat.
Step-by-step: Diet Claude
1. Turn on memory and Skills
Go to Settings → Memory and turn memory on — it's off by default. Anthropic rebuilt this feature in July 2026 so Claude keeps individual, categorized memory entries instead of one long unstructured note, and it's available on Free, Pro, and Max plans. While you're in settings, check Customize → Skills; Skills need code execution enabled, and a few Anthropic and partner nutrition-related skills can plug into a Diet Claude setup later if you want structured logging.
2. Create a dedicated Project
Click Projects → New Project and name it something you'll recognize, like "Diet Claude." Projects give you persistent custom instructions (roughly 8,000 characters), a knowledge base for uploaded files, and conversation history that stays grouped together — so every chat inside it starts already knowing your context.
3. Write the custom instructions
This is the part that actually makes it work. In my test, a short, specific instruction set beat a long one — Claude followed it more consistently. Mine read roughly: "You're helping me plan meals and track rough macros. My stats: [stats]. My goal: [goal]. Always show calories and protein per meal. Never suggest [allergy/dislike]. Ask before assuming I want to cut calories."
4. Load your baseline
Paste in a day or two of what you normally eat, plus any lab numbers or fitness-app exports you're comfortable sharing. Claude uses this as a reference point instead of guessing from scratch, and it noticeably improved the first meal plan I got back.
5. Test it on a real meal
Ask for a plan, then try a food photo. I photographed my actual lunch — a chicken bowl — and Claude estimated calories and protein within a range, flagging that mixed dishes are harder to size than single, clearly separated foods.
6. Correct it and save what works
When Claude misjudges a portion or ignores a preference, say so directly in the chat. With memory on, corrections tend to stick for later conversations in the same Project — though I still had to repeat myself occasionally when I switched devices mid-week.
Example prompts you can copy
These are close to what I actually used during testing:
- "My stats: 34, male, 5'10", 178 lbs, moderately active, goal is to lose about 1 lb/week. Build a 3-day, 2,000-calorie meal plan around chicken, rice, eggs, and vegetables. Show calories and protein per meal."
- "Here's what I ate today: [list]. Estimate total calories and macros, then tell me what to add at dinner to hit 150g of protein."
- "[Attach a food photo] Estimate the calories and macros here, and tell me what would make your estimate more accurate."
- "Rewrite this recipe to cut carbs by about a third without changing the flavor much: [recipe]."
- "Based on what you know about my week so far, what's one realistic change to my dinners that moves me toward my goal?"
Naming the constraint in the prompt (protein target, calorie ceiling, an ingredient to avoid) got noticeably more useful answers than open-ended requests like "help me eat healthier."
Diet Claude vs. the alternatives
| Setup | Cost | Memory across chats | Food-photo estimates | Best for |
|---|---|---|---|---|
| Plain Claude chat, no Project | Free–$20/mo | Only if memory is on; no saved instructions | Yes, ad hoc | One-off questions |
| Diet Claude Project (this guide) | Free–$20/mo | Yes — Project instructions + memory | Yes, with saved context | Daily planning and macro tracking |
| Dedicated nutrition app (e.g., MyFitnessPal-style logging) | Often free, paid tiers ~$20/mo | Yes, purpose-built | Yes, with a food database behind it | Precise daily logging |
Diet Claude wins on flexibility and cost — you're not paying for a second subscription if you already use Claude. A dedicated logging app still wins on precision, because it's checking a food database instead of estimating from a description or a photo.
Common mistakes to avoid
The biggest one: treating Claude's calorie and macro numbers as lab-accurate. A 2026 evaluation of large language models on food-photo estimation — Claude, ChatGPT, and Gemini against 52 real foods — found roughly 40% average error for weight and energy estimation from ChatGPT and Claude, and 65–70% error for Gemini, with macronutrient error running 42–110% and protein estimates off by more than 60% across all three models (Biolayne, January 2026). Use Claude's numbers as a rough guide, not a number you build a strict daily log around. Second mistake: skipping the Project setup and just chatting in a fresh window — you lose the persistent instructions and end up re-explaining your goals every time. Third: withholding allergies or medical constraints until after a bad suggestion, instead of loading them into the Project on day one. Fourth: photographing a crowded, mixed plate under bad lighting — accuracy drops further with larger, more complex portions, per the same study. Fifth, and most important: don't lean on this as a substitute for a doctor or registered dietitian, especially around any history of disordered eating — Claude is a planning aid, not a clinician.
Tools that make this easier
If you haven't set up Claude at all yet, start with my how to use Claude AI guide — it covers accounts, Projects, and prompting basics before you layer a Diet Claude setup on top. Food-photo accuracy depends partly on which model you're on; my Claude Opus 5 guide covers pricing and what the newer models actually improve on vision tasks. If you want Claude to remember context from other apps — like a fitness tracker or a notes app where you already log meals — see my Unabyss for Claude guide on connecting outside context over MCP. Curious whether ChatGPT handles this better? My Claude vs. ChatGPT comparison covers where each model actually wins, including on everyday reasoning tasks like this one. For getting more consistent, better-structured answers out of Claude in general, Claude Academy is a deeper prompting guide worth a read. And if you'd rather get a shareable, editable meal plan out of Claude instead of scrolling through chat text, my how to use Claude Artifacts guide shows how to turn a plan into a formatted document you can keep.
Frequently Asked Questions
Diet Claude: is it free?
Yes, in the sense that it doesn't cost anything beyond your existing Claude plan. Claude's Free plan includes memory and Projects at $0. Pro runs $17/month billed annually or $20/month billed monthly, mainly buying more usage, not new diet-related features.
How long does it take to set up Diet Claude?
About five to ten minutes: two minutes to turn on memory and create a Project, another five to write your custom instructions and load your baseline stats. The first meal plan and food-photo estimate each take under a minute to generate.
What is the easiest way to do this?
Start on Claude's Free plan with a single Project, a short instruction block with your stats and goal, and one food photo to test accuracy before you build a whole week of prompts around it.
Does Claude know exactly how many calories are in my food?
No. It estimates from your description or a photo, and published testing puts that estimate roughly 40% off on average for weight and energy, with even larger errors on protein and other macros. Treat it as a starting point, not a measurement.
Can Diet Claude replace a dietitian or an app like MyFitnessPal?
No. It's a flexible planning layer that costs nothing extra if you already use Claude, but a dedicated logging app checks a real food database, and a registered dietitian can account for medical history Claude has no way to verify.