Scientists have discovered just how obesity is linked to depression.
Researchers at the University of Glasgow say they've witnessed saturated fatty acids entering the brain via the bloodstream, affecting signals related to depression.
Testing on mice showed when they're fed a diet high in fat, much of it ends up in the hypothalamus, a part of the brain known to be linked with depression.
"We often use fatty food to comfort ourselves as it tastes really good, however in the long term, this is likely to affect one's mood in a negative way," said study leader Prof George Baillie.
"Of course, if you are feeling low, then to make yourself feel better you might treat yourself to more fatty foods, which then would consolidate negative feelings."
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The discovery could lead to new antidepressant medications that work better for overweight and obese patients, who don't respond as strongly or quickly to existing treatments as those of healthy weight.
"We all know that a reduction in fatty food intake can lead to many health benefits, but our research suggests that it also promotes a happier disposition," said Baillie.
"Further to that, understanding the types of fats, such as palmitic acid, which are likely to enter the brain and affect key regions and signaling will give people more information about how their diet can potentially affect their mental health."
One-in-three Kiwi adults are obese, according to the Ministry of Health. Around 8.6 percent of Kiwi adults used antidepressants last year, according to Statistics NZ.
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The research was published in journal Translational Psychiatry.