Health apps can encourage people to boost their fitness, such as running a certain distance, getting enough sleep, or eating the right foods.

But many apps do not use "evidence or theory-based" approaches to support these healthy changes and can give people goals that are "difficult to achieve".

That's according to researchers at University College London (UCL) who found fitness apps can leave people feeling discouraged from exercise.

Corresponding author Paulina Bondaronek of UCL said: "Fitness apps remain some of the most profitable and widely downloaded health tools globally. While they can benefit health, there's been far less attention to their potential downsides.

"When health is reduced to calorie counts and step goals, it can leave people feeling demotivated, ashamed, and disconnected from what truly drives lasting wellbeing."

The study, published in the British Journal of Health Psychology, looked at the negative behavioural and psychological consequences of commercial fitness apps reported by users on social media.

Researchers used artificial intelligence to analyse 58,881 posts on social media platform X referring to the five most profitable fitness apps, as of March 2022. These included MyFitnessPal: Calorie Counter, Strava, Weight Watchers, Workouts by Muscle Booster and Fitness Coach & Diet: FitCoach.

Several negative themes were picked up, including challenges of quantifying diet and physical activity, the complexity of tracking calories and exercise through oversimplified algorithms and emotional responses to the apps' notifications.

Some users felt overwhelmed by the apps and noted feelings of shame, disappointment and demotivation, leading to them quitting the apps and in some cases, healthy behaviours.

One post on X said: "I just got a notification from MyFitnessPal reminding me to log my dinner for today but I don't want to because I'm ashamed I just ate Dominos."

Another wrote: "How disappointing it is when you smash gym and MyFitnessPal for a day and there's no difference ... back to eating Lotus Biscoff spread out of the jar."

Researchers concluded there is a need for an app that prioritises wellbeing over quantitative goals.

Dr Darren Player, lecturer in musculoskeletal bioengineering at UCL and personal trainer, stressed that counting calories and steps are not suitable ways of measuring overall physical activity and health. But he doesn't think fitness apps are inherently bad.

"The psychological aspects are dependent on personality," Dr Player told The Independent. Some people want accountability, motivation and gratification from interacting with peers on apps like these. Other people would find this type of interaction demotivating."

Matt Roberts, a personal trainer to the rich and famous, said fitness apps can be "overwhelmingly positive" if they are used with the "right mindset".

"For some, the competitive side with peers can be discouraging, especially early on, but that shouldn't detract from the fact that most users gain real and lasting benefits from seeing their progress and learning how their daily habits affect their health," he added.

"The goal is to use the data for self-improvement, not self-judgement."

MyFitnessPal, Strava, Weight Watchers, Workouts by Muscle Booster and FitCoach have all been approached for a comment.

Why fitness apps could be doing more harm than good