Photo calorie counters may underestimate food energy by one-third

Popular mobile applications that promise to count calories in a meal from a single photograph systematically underestimate the energy value of food by about one‑third, according to a new study that compared four leading services against laboratory‑calculated reference values. The investigation tested MyFitnessPal, LoseIt!, CalAI and Appediet using 102 prepared dishes whose exact chemical composition and caloric content had been determined in advance from national nutrient tables. Portion energies ranged from 592 to 1,211 kilocalories. Researchers photographed each dish and submitted the images to the four apps, then compared the algorithmic outputs with the “gold‑standard” laboratory values. All four tools significantly underestimated calories. The mean error across the sample was approximately 33 percent, a discrepancy large enough to undermine any medical or weight‑loss regimen that relies on precise energy tracking. The average underestimation per portion, expressed in kilocalories, was: