Tracking your daily calories, nutrients and activity on a smartphone health app is a way of life for many who swear the apps are an invaluable crutch for helping them shape up. Global downloads of diet and fitness apps grew to 3.6 billion worldwide last year, with the UK market alone expected to be worth £982 million by 2033. Yet although they are intended to steer us along the path to wellness, new research suggests that the outcomes of relying too heavily on advice from a diet or fitness app can be life-changing for all the wrong reasons.
Dr Paulina Bondaronek, a research fellow in behavioural science at University College London, has been investigating health apps for most of the past decade. Her latest findings, published in the British Journal of Health Psychology, looked at nearly 60,000 posts on social media relating to five of the most popular health and fitness apps, including MyFitnessPal, Strava and WW (formerly Weight Watchers). With colleagues from Loughborough University and the University of Westminster, Bondaronek used AI models to select the 13,799 posts that contained negative comments, ranging from irritation at the technicalities of using an app, or at notifications to log calories or keep sugar consumption low, to shame and self-loathing at having to log “unhealthy” foods and falling short of unrealistic goals.
Many users expressed disappointment and anxiety at their slow progress towards algorithm-generated targets, felt “pestered” by app notifications and said that the difficulty of sticking to rigid goals quickly led to a loss of motivation. For some people this resulted in quitting, which thus defeated their intended purpose. Others developed feelings of failure and self-loathing that might exacerbate poor body image. It follows a review of 38 studies earlier this year in which researchers at Flinders University in Australia raised concern about growing numbers of diet app users becoming obsessive about targets, to the point of them developing disordered eating habits.
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“The focus on dietary restriction and weight loss in these apps may feed into restrictive or excessive behaviours, raising concerns for those people who have pre-existing concerns about their weight or body image,” says Isabella Anderberg, a researcher in the College of Education, Psychology and Social Work, who led the study.
Bondaronek says the wellness app market was launched in 2008 and remains largely unregulated, with apps in the wellness category not subject to the same rigorous guidelines as medical technology devices. “Many health apps are still based on very crude metrics, which is concerning,” Bondaronek says. “Nearly all of them start by asking your height, weight and how much weight you want to lose with no health professionals involved in determining whether this is an appropriate goal.” Algorithms have become more sophisticated, especially with the use of AI interpretation of data, but she says they still lack “the personalisation and tailoring needed to be fully accurate”.
Few previous studies had looked at the effects of app use on the longer-term mental and physical health of consumers. “We do know they haven’t been a fantastic intervention on a public health level because I don’t think we are getting healthier or living longer as a result of using them,” Bondaronek says. “Our latest study was an attempt to look at potential unintended consequences of app use.”
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She says her aim is not to vilify wellness apps but to highlight the potential negative side-effects. Her preference is for fitness apps that encourage social interaction rather than requiring users to do tasks such as daily steps on their own. “Self-monitoring and action planning are powerful behaviour change techniques,” Bondaronek says. “But often it means people miss out on the great potential of social connectedness for improving our health and happiness, which has proven psychological benefits, and we can overuse data-tracking apps to the point where they become detrimental.”
Even if you do find them a useful motivational tool, don’t pin all your hopes on an app’s targets or results. Most diet-tracking apps aren’t 100 per cent precise and come with a huge margin of error, according to Alex Ruani, a nutrition researcher at University College London and chief science educator at the Health Sciences Academy. “A systematic review and meta-analysis published in Advances in Nutrition found that mobile dietary record apps often under or overestimate energy, macronutrient and micronutrient intake,” Ruani says. “That team of researchers from the Netherlands reported ‘large variability among apps’ in real-life settings, so use them as rough guides, not gospel.” About to download an app? Here’s what you need to know.
Be wary of huge cuts in calorie intake
Apps can suggest larger drops in calorie intake than are needed or recommended
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A calorie deficit is needed to lose weight. “Yet many apps set calorie targets that are far too low, which can leave you hungry and demotivated,” says Bahee Van de Bor, a dietician and spokesperson for the British Dietetic Association (BDA). Bondaronek found that app-approved targets were not based on public health recommendations, such as NHS recommendations for daily calorie intake, but rather were dictated by a user’s own goals, which could mean unrealistic or unsafe recommendations.
One app user in her study reported being told to consume 700 fewer calories a day to reach her goal. A healthy and achievable amount is a deficit of about 500 calories per day. “Go too low and it becomes very difficult to meet micronutrient needs for iron, calcium, magnesium, folate, B vitamins and essential fatty acids without supplementation,” says Dr Linia Patel, a researcher in the department of clinical sciences and community health at the Università degli Studi di Milano in Italy and a spokesperson for the BDA. “If your app is suggesting a chronic drop below this you should start to question the validity of it.”
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Don’t become obsessed with macronutrient tracking
There’s no evidence to suggest macronutrient tracking beats calorie counting or other diet approaches
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Some apps push tracking macronutrients — fat, carbs and protein — rather than calories as a healthier route to weight loss with recommendations to increase the proportion of satiating protein to carbs. But Bondaronek found this too led to unhealthy obsessions for many. “When people started thinking just in terms of the fat and protein in their food it became all-consuming,” she says. “The difficulty of sticking to rigid goals led to loss of motivation.”
Macronutrient counting can give you a sense of what good nutrition looks like at first, Ruani says, but it’s not essential long term. “National guidelines recommend getting about half your calories from carbohydrates, with the rest split sensibly between protein-rich sources and healthy fats. For most people, that’s a perfectly adequate goal without constant logging.”
There’s no evidence that macronutrient tracking offers greater long-term weight-loss benefits than calorie counting or other diet approaches. A review of 14 popular diets in the BMJ found that “most macronutrient diets, over six months, resulted in modest weight loss” but that the effects on weight loss “largely disappeared” after a year. The only nutrient worth tracking on an app is fibre, Van de Bor says, which is included in the nutrition data on many apps. “Aim for about 30g of fibre a day. Fibre keeps you fuller for longer, stabilises blood sugar and feeds the friendly bacteria that support digestion, immunity and even mood.”
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Fertility and ovulation tracking apps are prone to inaccuracy
Bondaronek’s next study, due to be published soon, focuses on the vast market for menstrual tracking apps used by millions of women to log energy levels, symptoms such as cramps and cravings, and also to track ovulation and fertility. According to a review published last year and led by Joyce Harper, professor of reproductive science at University College London, the “femtech” market is huge, with period tracking marked as the second most popular type of app among adolescent females and the fourth most popular among adults.
Most tracking apps work by women inputting the date of their period so that a calendar-based algorithm can be applied to predict the start date of their next period, initially based on a 28-day cycle but using patterns and trends to learn about the user as they put in more information. Some apps have the option of adding biometric data, such as daily body temperature, cervical mucous consistency or hormone levels in the urine, but Kirsty Elliott-Sale, professor of female endocrinology and exercise physiology at Manchester Metropolitan University, who has published dozens of studies on menstrual tracking apps, says they are pointless.
“If you use a urine test to predict ovulation then you know when you are ovulating and don’t need to pay for an app on top,” she says. “The app is just a way to house the data you get from these tests.”
Most cycle-tracking apps don’t track anything you don’t tell them and their scientific validity has been held to question. Harper and her team said that apps promising to predict a user’s ovulation date usually 14 days after their period starts “have been proven to be ineffective, with a 21 per cent maximum probability of it being correct”.
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Don’t trust ‘cycle syncing’ apps for diet and workout advice
Some apps offer “cycle syncing” advice, tailoring diet and exercise to different phases of the menstrual cycle. Are they a good idea? “Absolutely not,” Elliott-Sale says. “These sorts of menstrual syncing apps are based on poor quality evidence and the scientific community would not be recommending translating the data they provide into practice.”
Some women do experience symptoms such as diarrhoea at certain phases of their cycle but she says they don’t need an app to tell them that it’s a good idea to tweak their diet. Apps that promise to sync your workouts to phases of the menstrual cycle are also a waste of time. “Many professional and Olympic sports bodies and coaches have asked their athletes not to use them as the advice they give is inaccurate,” Elliott-Sale says. “I have seen first hand when a women athlete refused to do the training her coach prescribed as her app said it wasn’t a good phase for her to do this, despite no scientific evidence to the app data.”
Sleep trackers might not help you sleep better
Sleep trackers can lead to obsessing over targets, which makes sleep patterns worse, not better
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Sleep trackers mostly use sound, heart rate and movement to estimate sleep phases and to provide a sleep score. For some, obsessing over the data leads to an unhealthy preoccupation with hitting sleep targets that has been dubbed orthosomnia. Ironically, it can lead to anxiety that makes sleep patterns worse, not better.
Kevin Morgan, emeritus professor of psychology at Loughborough University’s clinical sleep research unit, says that most sleep trackers only provide feedback on how well — or not — you have slept, which is often evident anyway by how tired you are feeling when you wake up. “There’s nothing a tracker can do to change the components of sleep,” Morgan says. “We can’t force our bodies to sleep better just because a tracker says we need more sleep.”
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