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BestCalorieApps
RC

Reuben Castelló-Frey, MS, RD

Lead Reviewer

Testing consumer health apps since 2018

About Reuben

Reuben Castelló-Frey is the lead reviewer at BestCalorieApps. If you’ve read a calorie tracker review on Wirecutter between 2020 and early 2025, there’s a decent chance Reuben either wrote it or signed off on it. He came to nutrition the long way — undergrad in nutritional biology at UC Davis, an MS at Cornell, then the dietetic internship and the RD exam, then four years writing for the most-read consumer recommendations site on the internet.

He joined BestCalorieApps as employee number two in January 2026 because he wanted to test apps the way he always thought they should be tested: long enough to actually break, against weighed reference meals, and without an affiliate budget shaping the conclusions.

What he tests

Reuben runs the bulk of our headline reviews and ranking pieces. That means: 30+ days of daily logging on every app we cover, photo-AI bake-offs against weighed reference plates, database accuracy spot-checks against USDA FoodData Central, and the slow boring work of evaluating whether a “free tier” is actually free.

Editorial focus

Reuben writes our flagship rankings (the Best Calorie Apps of 2026, the country guides, the use-case lists), our single-app deep dives, and most of the head-to-head comparisons. He works closely with Sienna on test-protocol design and with Dr. Brennan-Lee on anything that touches a clinical claim.

Conflicts of interest

Reuben holds no affiliate accounts with any app reviewed on BestCalorieApps. He owns no equity in any of the companies covered. He has been a paying user of MyFitnessPal Premium, Cronometer Gold, and PlateLens Premium during testing — paid out-of-pocket from the editorial budget so the experience matches what real readers see at signup.

Recent work

Articles & rankings

App reviews

Head-to-heads