Calorie-Tracking Apps Struggle to Crack the Weight Loss Code

A.I. claims to have solved calorie counting, but experts say the real solution lies beyond just tracking calories.

Published on Feb. 21, 2026

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Calorie-tracking apps have long promised to simplify weight loss by precisely calculating calories in and calories out. But experts say that even with advanced A.I. technology, the math behind the 'calories in, calories out' (CICO) model is flawed. Factors like protein intake, exercise accuracy, and individual metabolism make CICO an oversimplification. Rather than obsessing over calorie counts, experts recommend focusing on building healthier eating habits and recognizing the limitations of tracking tools.

Why it matters

As more A.I.-powered calorie-tracking apps hit the market, it's important for consumers to understand the limitations of CICO and not get caught up in the promise of precise calorie counting. Overreliance on these apps could lead to unhealthy behaviors and a false sense of control over weight loss. Understanding the bigger picture around metabolism, nutrition, and sustainable lifestyle changes is key.

The details

Many popular calorie-tracking apps like MyFitnessPal and the new A.I.-powered app CalAI claim to provide highly accurate calorie counts. However, experts point out that even with advanced databases and photo-scanning technology, calorie counts can still be off by up to 20% due to factors like portion size estimation and recipe variations. Additionally, research shows exercise doesn't burn as many calories as commonly believed, with the body compensating by reducing energy expenditure in other areas. Focusing solely on CICO can lead to an unhealthy obsession and overlook other important factors like protein intake, which can affect weight loss independently of calories.

  • In the early 2010s, researcher Herman Pontzer tested the theory that hunter-gatherers burned far more calories than sedentary modern humans, but found they burned no more calories daily when adjusted for body size.
  • In 2025, a study found that even the Apple Watch is inaccurate for assessing energy expenditure.

The players

Herman Pontzer

A researcher who has conducted extensive studies on calorie expenditure, challenging the common assumption that exercise dramatically increases daily calorie burn.

Zach Yadegari

The 18-year-old founder of the calorie-tracking app CalAI, which uses A.I. to analyze food photos and calculate calories.

Mike T. Nelson

An exercise physiologist who has helped many clients lose weight, and who disagrees with the oversimplification of the CICO model.

Stuart Phillips

A professor of kinesiology at McMaster University and a leading researcher on the effects of protein on body composition.

Andrew Heffernan

The author of the article, a health, fitness, and Feldenkrais coach, and an award-winning health and fitness writer.

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What they’re saying

“Telling the average person to just move more and eat less is like telling a depressed person to just have a nice day.”

— Mike T. Nelson, Exercise physiologist (menshealth.com)

“CICO isn't wrong, but it is incomplete.”

— Stuart Phillips, Professor of kinesiology (menshealth.com)

“For someone who has never logged anything, I do think apps are probably useful because they create that awareness.”

— Mike T. Nelson, Exercise physiologist (menshealth.com)

What’s next

Researchers continue to study the complex relationship between diet, exercise, and weight loss, exploring factors beyond just calorie counting.

The takeaway

While calorie-tracking apps can provide useful awareness, true weight loss success depends more on building sustainable healthy habits and recognizing the limitations of CICO, rather than obsessing over precise calorie counts.