Calorie content influences food choices regardless of obesity status, study finds

Higher-calorie foods are preferred by individuals regardless of their obesity status, even when taste and texture are identical, according to a study published in PLOS Biology by Albino Oliveira-Maia and his team at the Champalimaud Foundation in Portugal.

The research highlights how eating triggers signals to the brain about a food's energy content, influencing preferences beyond flavour alone. For individuals living with obesity, impairments in dopamine-related brain regions may intensify reward-driven eating and a tendency toward calorie-dense foods high in fat and sugar. Interestingly, weight loss achieved through bariatric surgery appears to normalise reward-related eating behaviours, although the mechanisms driving these changes remain unclear.

The study examined food preferences among 61 participants divided into three groups: individuals with obesity, post-bariatric surgery patients, and non-obese controls. Participants consumed sweetened low-fat yogurt, with and without added maltodextrin, a calorie-rich carbohydrate that does not alter taste or texture. Regardless of obesity status or surgery history, all groups ate more of the calorie-enriched yogurt, even though both varieties were rated as equally enjoyable.

To explore the neurological basis of these behaviours, researchers used imaging techniques such as radioactive iodine labeling and single-photon emission computed tomography to study dopamine receptors in the brain. Consistent with previous findings, individuals living with obesity displayed lower dopamine receptor availability compared to non-obese controls. However, this measure normalised in post-surgical participants, aligning with non-obese individuals.

Despite these neurological changes, preferences for calorie-dense foods remained unchanged after surgery. The results suggest that while bariatric surgery may alter eating behaviours and reduce overall food intake, it does not necessarily shift preferences away from energy-dense options.

The authors noted, “We were intrigued to find that behaviour was driven toward higher-calorie foods without consistent changes in the pleasantness of carbohydrate-enriched flavours. This behaviour persisted in individuals with obesity and after weight-loss surgery, even as significant differences in their brain dopaminergic systems were observed.”

This research sheds light on how the brain's response to calories influences food choices and how these mechanisms persist despite physical or metabolic changes. Understanding these pathways may be key to developing more effective interventions for obesity and weight management.