New research has identified obesity as a significant driver of severe outcomes from infectious diseases, prompting calls for urgent public health measures to support weight management and vaccination. A study involving over half a million people suggests that individuals living with obesity face a 70% higher risk of hospitalisation or death from infections compared to those with a healthy weight, as outlined by The Guardian.
The analysis, published in the Lancet, indicates that this heightened risk applies to a wide range of illnesses including flu, pneumonia, gastroenteritis, urinary tract infections and Covid-19. It estimates that obesity may already be a factor in roughly 600,000 of the 5.4 million global deaths from infectious diseases annually, equating to about one in ten such fatalities.
Dr Solja Nyberg of the University of Helsinki, the study’s first author, warned the situation could deteriorate. “As obesity rates are expected to rise globally, so will the number of deaths and hospitalisations from infectious diseases linked to obesity,” she said. Dr Nyberg stated there is an urgent need for policies that help people stay healthy and support weight-loss, such as access to affordable healthy food and opportunities for physical activity. She added that, in the meantime, it is “especially important” for those living with obesity to keep up to date with their vaccinations.
The research used data from 67,000 adults in two Finnish studies and 470,000 adults from the UK Biobank. Participants, with an average age of 42 in the Finnish group and 57 in the UK cohort, had their body mass index (BMI) assessed and were followed for an average of 13 to 14 years. It found that people with a BMI of 30 or higher—classified as obesity—had the substantially increased risk compared to those with a healthy BMI between 18.5 and 24.9, with the risk rising further as body weight increased.
Professor Mika Kivimäki from UCL, the lead author, suggested broad biological mechanisms might be involved. “It is plausible that obesity weakens the immune system’s ability to defend against infectious bacteria, viruses, parasites or fungi, therefore resulting in more serious diseases,” he said. Prof Kivimäki noted that evidence from trials of GLP-1 weight-loss drugs, which reduce obesity, also appears to lower the risk of severe infections, but said additional research is required to confirm the underlying mechanisms.
The study revealed variations in the proportion of infection-related deaths linked to obesity between countries. It found about one in six such deaths were connected to obesity in the UK and one in four in the United States, while Vietnam had the lowest proportion at 1.2%.
The research, which was funded by Wellcome, the Medical Research Council and the Research Council of Finland, had limitations. It relied on observational data and could not confirm causality. Dr Sara Ahmadi-Abhari of Imperial College London, a co-author, cautioned that “estimates of the global impact give a sense of how large the problem may be, but they should be interpreted with caution.”
