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The disease

Obesity describes the condition of being too heavy for your height. Although there is debate as to whether obesity should be categorised as a disease in its own right, there is no question that obese children and adults are at much greater risk of both short and long-term health problems. In fact, the worldwide ‘obesity epidemic’ is the greatest driver of the current epidemic of chronic disease.

Nearly 2 in 3 adults (63%) and more than 1 in 4 children (28%) in Australia are now considered overweight or obese, in New Zealand 2 in 3 adults (66%) and 1 in 3 children (33%) are now considered overweight or obese.

The cause

The highly processed, and energy dense Western diet is the root cause of obesity. Obesity is rare in populations consuming traditional diets based predominantly on whole plant foods, but has become a worldwide epidemic with increasing Westernisation of diets and lifestyles.

The nutrition prescription

A whole food plant-based eating pattern is naturally low in energy density, while being high in nutrient density. Transitioning to a whole food plant-based diet diet results in rapid, sustainable, and healthy weight loss:

  • A recent meta-analysis of randomised controlled trials has found that more weight can be lost on vegetarian diets than non-vegetarian diets, and vegan diets may promote more weight loss than vegetarian diets. [1]
  • In a randomised controlled trial of people who were either overweight or obese, those who adopted a whole foods plant-based diet lost 12.1kg on average after 6 months, and maintained an 11.5kg weight loss at 12 months, despite no requirement for energy restriction or exercise.[2]

Medical supervision of diet change is essential

Shifting to a low fat whole food plant-based diet will often lead to rapid reductions in medication needs. People who are on medications for high blood pressure or blood sugar control especially should seek medical supervision.

Video overview from

Further resources

Plant Based Health Australia logo

Plant-based Health Australia: detailed information on weight management, including sections on energy density, food addiction, satiety and low-fat diets.

PCRM logo

Physicians Committee for Responsible Medicine: weight loss summary, ‘healthful habits’ guidance and links to further tools and resources.

  1. Huang, R. Y., Huang, C. C., Hu, F., & Chavarro, J. (2016) Vegetarian diets and weight reduction: A meta-analysis of randomized controlled trials. Journal of General Internal Medicine, 31(1), 109-116.

  2. Wright N, Wilson L, Smith M, Duncan B, McHugh P. The BROAD study: A randomised controlled trial using a whole food plant-based diet in the community for obesity, ischaemic heart disease or diabetes. Nutr Diabetes. 2017 Mar 20;7(3):e256.

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