Frozen concentrate has 51 kcal per 100 g — dilute before drinking. The concentrate is meant to be mixed with water, so a reconstituted glass sits around 45–55 kcal per 100 ml. Log the prepared juice, not the concentrate weight, or you'll triple-count the calories.
How should I track Pineapple juice, frozen concentrate, unsweetened, diluted with 3 volume water?
Liquid calories from Pineapple juice, frozen concentrate, unsweetened, diluted with 3 volume water are easy to overlook because drinks do not trigger the same fullness signals as solid food. A meta-analysis (Wehling & Lusher, Am J Clin Nutr 2021) confirmed that people underreport beverage intake more than solid food. Most people pour 30–50% more than the label serving size without realizing it. Use a kitchen scale to weigh your glass or bottle once — you will know your exact pour going forward. This one calibration step can save you from hundreds of untracked calories per week.