That ice cream sundae, a big bowl of mac ‘n’ cheese: These are the “comfort” foods that people so often turn to. Some studies have shown that eating high-fat foods make different regions of the brain light up; they become addictive because people keep turning to them for that pleasurable sensation. A new study from the International Journal of Obesity suggests the opposite: University of Montreal researchers found that a high-fat diet led to depressive and anxiety-like behaviors in mice.
Canada.com describes the study (which involved the mice undergoing some very stressful moments). One group of mice (who were prone to obesity) were fed a diet high in saturated fats, the other low-fat food. After 12 weeks, the researchers put the mice through a stress test; rodents who are stressed will freeze or run for a corner, rather than explore,
Mice exposed to the high-fat diet were considerably less active, explored less and avoided open areas.
In a swim test used to measure “behavioural despair” — a test also widely used by drug companies to screen new anti-depressants — mice were forced to swim in a glass cylinder filled with water for six minutes.
“Animals that give up quickly — they stop swimming and just float and stop trying to pull themselves out of the beaker — that’s (a sign of) self-helplessness,” [lead researcher Dr. Stephanie] Fulton said
Mice on the high-fat diet “actually gave up” and attempted fewer escapes, she said.
A study of the mice’s brains revealed that those fed a high-fat diet had higher levels of the stress hormone, corticosterone. Researchers also noted changes in the expression of proteins that control the firing of neurons and, notably, in parts of the mice’s brains that regulate emotions and reward.
Fulton, a principal investigator at the Centre hospitalier de l’Universite de Montreal and a member of the Montreal Diabetes Research Centre, also points out that, while high-fat foods may feel comforting in the short term, in the long term, “increasing adiposity (fat mass)” can have “negative effects on mood.”
Fulton’s research coheres with another study linking fast food consumption to depression.
Anecdotally: My late mother-in-law spent the last 50+ years of her life depressed, at times severely enough to require hospitalization. She was very overweight, never exercised (never really got out of her chair) and fought off my husband’s attempts to have her walk with him down the driveway. Food was both a comfort and an obsession; her diet was dairy-based and full of fat and sugar (she always talked about dessert as a meal was being served). Getting her to eat stir-fried broccoli or a bit of salad was like trying to get a picky toddler to eat one bite of a carrot. Her depression and anxiety arose from a variety of sources — she was very intelligent but had only attended a year of college because her father insisted she study science not the history she loved; she revelled in working for a Manhattan radio station but quit to get married — and the feeling was, she’s struggling already, why not just let her eat what she wants?
But could all those “comfort” foods only have been adding to her discomfort, physically and mentally?
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