Telling people they have a genetic risk of obesity does not necessarily help them lose weight or change their eating habits — and being told they have a low risk may actually encourage unhealthy behaviour, a Polish-Greek study has found.
Researchers found that information about genetic risk alone rarely produced lasting changes in weight, diet or physical activity. People at high genetic risk were more likely to become motivated to change their behaviour, but meaningful weight loss was seen mainly when genetic information was combined with intensive professional support.
The findings come from an analysis of 23 randomised controlled trials involving almost 8,000 people, conducted by researchers from SWPS University's CARE-BEH Center for Applied Research on Health Behavior and Health and Harokopio University in Greece.
The study was published in Obesity Reviews.
Obesity is a global health problem. In 2022, about one in eight people worldwide were living with obesity, while excess body weight was associated with an estimated five million deaths in 2019.
Although genetic factors influence the risk of obesity, researchers say they interact with environmental, psychological and physiological factors. Lifestyle also plays an important role, with diet and physical activity affecting both the risk of obesity and related conditions such as type 2 diabetes and cardiovascular disease.
As genetic testing becomes increasingly accessible through personalised medicine, the researchers wanted to determine whether giving people information about their genetic risk could actually change their behaviour — and how that information should be communicated.
They analysed more than 2,000 publications, ultimately identifying 23 randomised controlled trials covering 18 interventions and nearly 8,000 participants.
The results showed that simply informing people about their genetic susceptibility to obesity was generally not enough to produce lasting changes.
“Many of us hope that knowing our DNA profile will provide a clear path to health and maintaining a dream figure. Unfortunately, things are not that simple. The conclusions from the study show that information about genetic risk alone does not work. Without additional support, providing patients with information about their genetic background usually does not lead to lasting changes in weight, eating habits, or physical activity levels”, said Zofia Szczuka, PhD, a psychologist at SWPS University and first author of the study.
The researchers said the finding is consistent with theories suggesting that interventions focused primarily on communicating health risks tend to produce either short-lived behavioural changes or no change at all.
In some cases, the information could even have the opposite effect.
People told they have a low genetic risk of obesity may develop a false sense of security, the researchers found. Believing they have “good genes” can make them less concerned about their diet or physical activity and, paradoxically, lead to poorer choices.
The picture was different among people told they had a high genetic risk.
In this group, information about genetic susceptibility could increase motivation to change behaviour. But the researchers found that positive outcomes such as actual weight loss occurred mainly when genetic information was combined with intensive professional support.
Such programmes included setting specific goals, monitoring progress, providing feedback and offering social support.
“Interventions must be personalised not only in terms of the patient's genes, but also specific action plans and goals. The most promising results are achieved with complex programs lasting, for example, 12 months, which combine communication about genetic risk with behavioural change techniques”, Szczuka said.
The researchers concluded that genetic risk information is most useful when it is accompanied by a clear plan for changing behaviour and continued support.
They also argued that effective communication should do more than simply increase a patient's knowledge of their genetic risk. It should help people develop a sense of control over their behaviour and provide practical strategies that can become part of their daily routines.
The study was conducted as part of the BETTER4U project consortium, funded by the European Union's Horizon Europe programme.
PAP - Science in Poland
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