London School of Hygiene & Tropical Medicine

Mobile phone applications (apps) can help people eat more fruit and vegetables and reduce meat consumption, according to new research led by the London School of Hygiene & Tropical Medicine (LSHTM) and funded by the NIHR School for Public Health Research (SPHR).

The findings, published in the International Journal of Behavioral Nutrition and Physical Activity, suggest that apps could support dietary shifts that improve public health and reduce greenhouse gas emissions.

Globally, the mobile health (mHealth) sector has expanded rapidly, with recent estimates suggesting over 350,000 health-related apps are available and smartphone ownership exceeds 80% of adults in high-income countries, providing an unprecedented platform for dietary interventions.

It has been estimated that the global food system is responsible for around one-third of greenhouse gas emissions, largely driven by the production and consumption of animal-sourced foods.

At the same time, poor diets are a leading cause of obesity and diet-related diseases, with substantial health, economic and social costs.

Diets in high-income countries typically contain a high proportion of carbon-intensive foods (e.g. meat), and are low in fruit, vegetables and legumes. Therefore, transitioning to healthier alternatives presents an opportunity to reduce food-related greenhouse gas emissions while also improving public health.

To assess whether technology could help address these challenges, LSHTM researchers conducted the first systematic review and meta-analysis on the effectiveness of mobile apps in supporting dietary change.

From an initial pool of 7,356 studies, 21 met the criteria for inclusion in the final review. Together, these involved 12,898 participants across 10 countries and territories, including the USA, UK, Spain, Italy, China, the Netherlands, Australia, New Zealand, Switzerland, and Puerto Rico. The analysis showed that, on average, app users increased their fruit and vegetable consumption by more than three portions per week, and reduced meat intake by a smaller degree.

The review classified interventions according to the behaviour change techniques they used and their modes of delivery to examine not only whether the apps worked to change behaviour, but which elements of the apps worked, and how they were implemented. This revealed that apps delivering targeted messages via notifications or message boards were the most successful.

The analysis also found that apps focused on meat reduction rather than generic diet-related apps were found to be most effective for meat reduction. This provides a new insight, in contrast to previous research suggesting that meat intake is particularly hard to change through informational or educational tools only.

Retention rates were higher than expected, with four in five study participants continuing to use the apps on average. Diet changes were shown to peak at around 12 weeks after participants started to use the apps, but there was limited evidence to inform whether these changes were sustained over time.

The researchers note that apps were largely used by those not meeting dietary guidelines, suggesting that, unlike fitness apps (often used by already healthy, active people) they may reach groups most in need of support, rather than widening health inequalities. However, access to smartphones and digital literacy varies, and further research is needed to ensure app-based approaches do not exclude groups with lower access to technology that may differ in socioeconomic status to the study populations.

The researchers also highlighted gaps in the evidence, including limited data on other important food groups such as dairy, legumes, fish and nuts, and a lack of long-term research, with the average study being only 12 weeks in duration.

Esther Curtin, PhD Student at LSHTM and lead author on the study said: “The diet and nutrition app industry is huge and evolving all the time – about 1 in 5 people in the UK use apps related to nutrition or fitness.

“Given the widespread uptake of these apps and typical baseline diets of adults in high-income countries, carefully designed mobile apps could help bring diets closer to the recommended intake of fruit and vegetables, and reduce greenhouse gas emissions.

“The new EAT-Lancet Commission on healthy, sustainable and just food systems found that shifting diets could prevent up to 15 million premature deaths per year, partly through consumption of foods such as fruit, vegetables, meat, legumes, and dairy, all of which were captured in our study.

“Future independent evaluations of commercial apps will be crucial to further unpick their potential, to understand in what contexts and for whom these interventions work best.”

The review provides insights that could be used by app developers when designing and further improving diet-related behaviour change apps, including those used by national governments and health practitioners. As a next step, the team is collaborating with an existing app to run a pilot randomised controlled trial to understand the effects in a group of local authority employees in England.

Rosie Green, Professor of Environment, Food and Health at LSHTM and co-author on the study said: “We know diets in countries like the UK need to change, not only to improve people’s health but also to reduce the impacts of diets on the environment. This will mean encouraging people to eat more fruit and veg and less meat, but how to do this is a difficult question.

“This study adds an important piece of the puzzle by showing that smartphone apps can be a part of the solution, and we can start to explore what elements of apps are most effective in promoting diet changes.”

Publication

Curtin E, et al. The effectiveness of mobile app-based interventions in facilitating behaviour change towards healthier and more sustainable diets: a systematic review and meta-analysis. International Journal of Behavioral Nutrition and Physical Activity. DOI: https://doi.org/10.1186/s12966-025-01823-7