Studies finds a major link between fast food, sugar and depression.

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Sugary food might be your go-to pick-me-up on bad days, but it could be contributing to your mental state in the first place.

A series of new studies have found a significant link between the sweet stuff and a disease the World Health Organisation says is one of the biggest burdens on society: Depression.

Around one million Australians currently suffer from depression and the new research published in the Journal of Health Pyschology suggests that what we eat could be a contributing factor.

RELATED: The unexpected ways depression can affect your body.

Scientists at San Diego State University Research Foundation looked into the relationship between trans saturated fats (which you find in cakes and other fast food) and emotional regulation.

They found that fast food can make you depressed and less able to control your emotions.

Examining archival data of 1699 men and 3293 women that included their trans fat intake and emotion responses, the study found that those with higher intakes of trans fats experienced “difficulties with emotional awareness” and a lower level of emotional “clarity”. (Post continues after gallery.)

Individuals with lower trans fat intake were associated with improved emotion regulation.

And that’s not the only evidence suggesting that what we eat can affect our mental health.

RELATED: 10 simple tips for creating better mental health this week

A study published this week in the American Journal of Clinical Nutrition, corroborates the new information, with researchers finding that high glycemic index (GI) diets could be a major risk factor for depression in postmenopausal women.

The GI index refers to a scale that ranks foods containing carbohydrate by how much they raise your blood sugar.

Looking at data from food questionnaires and a scale that measures symptoms of depressive disorders from postmenopausal women in the Women’s Health Initiative Observational Study, Columbia University Assistant Professor James E. Gangwisch and his team of researchers studied the results of roughly 70,000 women.

None of the participants had suffered from depression at the time of data collection but had their baseline measurements taken between 1994 and 1998, then again after three years.

The team found that diets rich in refined grains and added sugar, so higher on the glycemic index, were found to be associated with greater odds of depression. Added sugars in particular were strongly associated with depression.

Interestingly, they also concluded that some aspects of diet could actually have a protective effect against developing depression. These included fibre, whole grains, whole fruits, vegetables and lactose.

RELATED: Does diet or exercise have the biggest impact on your health?

Although the researchers could only find an association rather than a mechanism, they believe that one possible answer is that eating too much sugar could act as a risk factor for inflammation and cardiovascular disease, which have both been linked to causing depression.

While it's been well publicised that a diet heavy in trans fats and sugars can have a range of negative health consequences such as high cholesterol levels that lead to heart attacks, heart disease and strokes, the effect on mental health is not as widely accepted. (Post continues after gallery.)

According to Oxford University's Dr Alex Richardson, the nature of the problem makes it hard to quantify.

"We have quite enough evidence, but the scientific community insist on 'randomised controlled double-blind placebo trials' - hard to do, particularly for long periods. Instead, we should look at the totality of evidence," she told The Guardian.

Gangwisch stresses that further research is needed, particularly to see whether these results also apply to different groups of people like men and younger women - however diet is definitely worth considering for people who do suffer from depression, despite how difficult it might be to raise.

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"It's hard enough to get the general public to avoid those kind of foods, but it's even harder to get someone who suffers from depression to avoid and give them up," he told Time.

"[But] I think it's important and I think it has a big effect on your mood and how you feel and your energy level. If it's something that people can change, they really would benefit from it."

Do you think what you eat could affect your mental health? Is it something you're conscious about?