Melbourne: A new study has revealed what leads to the "golden triangle of happiness" - a loving partner, up to 100,000 dollars of household income and a social activity that offers a sense of purpose.

According to Deakin University psychologist Professor Robert Cummins, being fat is no barrier to happy life, website reported.

Prof Cummins has taken aim at doctors and societal attitudes which push the idea that fat or obese people are unhappy.

Doctors should start thinking more about their patient's overall happiness instead of focusing solely on high blood pressure and cholesterol problems, he said.

The culmination of 29 surveys over 12 years of research has found that (apart from having a catastrophic medical condition) health is not part of the three elements that comprise the golden triangle.

Prof Cummins identified those in Obese Class 2 or 3, who have a body mass index of 35 or more, as being the cut off point for happiness.

Anyone with a BMI under that will not have their weight impacting on their happiness.

So if you're 1.8m tall and 110kg, or 1.5m and 75kg, you're classified as obese but not so obese, it will impinge on your happiness.

Beyond that point social exclusion and interference with day-to-day routines starts to have an effect on an individual's happiness, Prof Cummins said.

The culmination of 29 Australian happiness surveys over 12 years by Melbourne's Deakin University has revealed it doesn't matter where you live, whether your collar is white or blue or whether you've got kids or not - if you live within the golden triangle you're more than likely to have a permanent smile on your face.

Prof Cummins has also offered hope to Australia's ageing population by saying that life really does get better with age.

(Agencies)

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