Impact of a novel ultra-processed foods and drinks diet on metabolism and behaviour in adolescent female and male rats.

Mental health affections induced by ultra-processed foods (UPF) in humans have been consistently reported. We aim to develop an experimental UPF diet based on typical UPF products consumed by human adolescents and to characterize its impact on health and behaviour in male and female rats. In a first experiment, 30 UPFs were administered, one every day, plus standard chow, compared with rats fed standard chow. In a second experiment, we combined selected UPFs from the first experiment in 4 menus, consisting in 4 solid and 1 liquid item each one. After weaning, 48 rats were divided in 4 groups according to sex and diet. UPF groups were fed the UPF diet, plus standard chow, and STD groups only chow over 6 weeks.UPF feeding induced increased body weight, abdominal circumference and total and visceral adiposity, as well as hyperglycaemia, hypertriglyceridemia and hyperleptinemia compared to STD feeding. UPF feeding also increased activity in the hole board, diminished anxiety-like behaviour in the elevated plus maze, and marginally improved object recognition in females in the object recognition task. In conclusion, the designed UPF diet induced several metabolic alterations and behavioural changes and may be helpful to further study the UPF effects on health and the underlying mechanisms during longer exposures.