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High Fat Diet Linked to Depression

Researchers say a diet too high in saturated fat may lead to brain changes and increased depression and anxiety.

Recent clinical studies have shown that obese people are at greater risk of depression but these studies have shed no insight on why this might be so, after all, eating fatty foods generally makes us feel pretty good, right?

To learn more, researchers in Montreal developed an animal model study to test the impact of a high fat diet, and they found that a diet high in fat, particularly saturated fat, was associated with increased depression and anxiety.

The Study

A group of obesity prone rats was spilt into 2 groups. For 12 weeks, one group consumed low fat chow and the other had access to a chow high in saturated fat.

After the 12 weeks of eating, the rats were given a series of tests to measure anxiety and depression, such as testing how rats respond to a new environment (a test of anxiety) and testing how long rats will swim for when placed in a tank of water ( a measure of depression/learned helplessness)

The Results

  • Rats fed a high fat diet showed much higher levels of anxiety and depression than rats fed a healthier low fat chow.
  • Rats on the high fat diet also had higher levels of neural stress linked corticosterones and changes to signaling proteins in the brain’s reward and regulation systems.
  • Rats fed a high fat diet but one based on healthier fats, like olive oil, experienced less depression and anxiety than rats on a high saturated fat diet


Based on the study results, lead researcher Dr. Stephanie Fulton hypothesized an explanation for the obesity-depression link, explaining, “In the short-term high-fat food feels comforting, but in the long-term, and with increasing adiposity (fat mass) it is having negative effects on mood. We know that diet is a large contributor to the obesity epidemic throughout the world. Fat-rich foods can actually cause chemical reactions in the brain in a similar way to illicit drugs, ultimately leading to depression as the ‘comedowns’ take their toll.”

The full study results can be found in the International Journal of Obesity

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