Scientists have produced more evidence outlining the dangers of a high-fat diet, with a new study linking the resultant increase in body weight and blood sugar levels to anxiety and depression.

The researchers behind the study, published in the British Journal of Pharmacology, found that the effects of a high-fat diet can also lead to measurable changes in the brain.

The experiments with mice showed a strong correlation between high-fat diets and mental health issues, while taking mice off a high-fat diet completely reversed the animals' metabolic impairments and lessened their anxious symptoms. Meanwhile, the beneficial effects of an antidepressant were blunted in mice fed a high-fat diet, suggesting physical activity and other forms of weight loss may be more viable options for battling depression.

"When treating depression, in general there is no predictor of treatment resistance," said Dr Bruno Guiard, senior author of the study.

"This finding reinforcing the idea that the normalisation of metabolic parameters may give a better chance of achieving remission, particularly in depressed patients with type 2 diabetes."

Previous studies have identified how high-fat diets can alter behaviour and produce signs of brain inflammation, even in the absence of obesity, while recent research from the US National Institute of Diabetes and Digestive and Kidney Diseases found that cutting fat, not carbs, is key to losing weight.