The short answer
Nexus is the one to start with. It is listed in both the ChatGPT plugin directory and the Claude connectors directory, so adding it is one tap with no developer mode. It logs meals, workouts and body weight in one log that both assistants share, and it is free.
Pick something else if you need a specific extra: Zolt for an adaptive TDEE estimate, Heza if you want runs synced from a Garmin or COROS watch, or Nutrition MCP if you want open source you can host yourself.
Side by side
| Add in ChatGPT | Add in Claude | Workouts | Price | |
|---|---|---|---|---|
| Nexus | Plugin directory, one tap | Connectors directory, one tap | Yes: plans with 200+ illustrated exercises, tick off sets | Free |
| Zolt | App directory | Custom connector (paste a URL) | Reads synced workouts | Free tier with 30 food lookups a day; Pro paid |
| Calories Club | App directory | Custom connector | Not confirmed | Not confirmed |
| Ziva | Not confirmed | Connectors directory | Not confirmed | Free |
| CalorieGoals | Not confirmed | Connectors directory | Not confirmed | Premium subscription required |
| Nutrition MCP | Developer mode | Connectors directory | No (meals, water, weight) | Free, open source |
| Heza | Developer mode | Custom connector | Yes: lifting and runs | Free during early access |
| IZeat | Developer mode | Custom connector | Not confirmed | $99.99 a year after a 7-day trial |
| Forkmate | Where your plan allows custom connectors | Custom connector | Not confirmed | Free (beta) |
| Fitaily | Custom connector | Custom connector | Reads workouts from the Fitaily app | Free with a Fitaily account |
| MyFitnessPal | App directory | No | No | Free in ChatGPT; it gives recipes and targets but does not log meals |
Sources: Zolt, Calories Club, Ziva, CalorieGoals, Nutrition MCP, Heza, IZeat, Forkmate, Fitaily, MyFitnessPal in ChatGPT. "Not confirmed" means we could not find it on the tracker's own pages.
Why the directory matters
A tracker that isn't in ChatGPT's directory has to be added as a custom app in developer mode. That is a web-only setting, it shows a warning before you can continue, and the trackers' own setup pages say not every ChatGPT plan has it (IZeat, Nutrition MCP). Setup has to happen on a computer, and on a plan without developer mode those trackers can't be added at all.
Nexus passed review at both OpenAI and Anthropic. In ChatGPT you open the Nexus plugin and tap Add. In Claude you open the Nexus connector and tap Connect. Either way it takes about a minute, on any device.
Why Nexus
One log in both assistants. Log breakfast in ChatGPT and ask Claude about your protein at night. Both read the same entries.
Meals, workouts and weight together. Ask for a workout and you get a page of illustrated exercises to tick off set by set. Finish turns the ticked sets into your workout log. Most chat trackers only log food.
A card you can fix with a tap. Every log shows your day on a card with calories and protein against your goals. Tap a meal to change its numbers, or tap a set to change the weight.
Photo, voice and labels are included. Send a photo of a plate, a nutrition label or a restaurant bill, or dictate the meal. Nothing is behind a paywall.
Try it without an account. The sandbox runs the real tools and the real card on throwaway data.
Questions
What is the best calorie tracker for ChatGPT?
Nexus. It is in the ChatGPT plugin directory, so it adds with one tap and works on the ChatGPT apps for iPhone, Android, web and desktop. It logs meals from text, photos or voice, plus workouts and body weight, and it's free.
What is the best calorie tracker for Claude?
Nexus. It is in the Claude connectors directory and works on Claude's web, desktop and mobile apps. Your log is shared with ChatGPT if you use both.
Can ChatGPT track calories on its own?
ChatGPT can estimate calories from a description or a photo, but it doesn't keep a dependable daily log across chats. A tracker such as Nexus saves each entry with its date, so "how much protein did I eat this week" is answered from what you logged. More in how to track calories in ChatGPT.
Is there a free calorie and workout tracker for ChatGPT?
Yes. Nexus logs meals, workouts and body weight for free, with photo and voice logging included.