The country's 38 percent increase in the five-year period was followed by Indonesia with 33 percent and Malaysia with 27 percent, the Fitch Solutions Macro Research said in its newly-released report on rising obesity levels and its effect on healthcare systems in the Asia Pacific.

All six Southeast Asian countries - Vietnam, Thailand, Singapore, the Philippines, Malaysia, and Indonesia, which are the focus of the report, saw a rise in the number of obese adults.

Elsewhere in Asia, South Korea matched Vietnam’s increase of 38 percent while for Japan it was 14 percent.

The increase of overweight and obesity was lower in developed countries like the U.K. (10 percent) and the U.S. (8 percent).

But Vietnam had the lowest rate of obese people in 2014 - 3.6 percent - compared to 5.7 percent in Indonesia and 13.3 percent in Malaysia.

The big picture

The obesity surge in many countries through 2014 was not an isolated growth – it continued the long-term upward trend in Asia Pacific from 1990 where 34.6 percent of adults were obese, the data shows. By 2013, the number grew to 40.9 percent.

Children in Asia Pacific were getting fatter too, with a rise of 38 percent in obese children between 2000 and 2016.

Fitch’s findings in Asian children aspect dovetailed with the most recent study about Vietnamese children published by Vietnam’s National Institute of Nutrition earlier this month.

The study discovered 42 percent of children in Vietnam’s urban areas are overweight and/or obese, compared to 35 percent in rural areas out of 5,028 students. 

Mortality rates increase with increasing degrees of overweight based on BMI, according to WHO. It said obesity also jacks up the risk of cancer of the breast, colon, prostate, endometrium, kidney and gall bladder.

Consequentially, the rise of overweight people come with a cost. The Fitch analysts estimated that Vietnam might have to pay around 2.5 percent of the overall healthcare spending, including medication and hospitalization costs, due to high obesity levels.

The global research firm enlisted "shitfting lifestyle" as the reason that gave rise to the growing obesity levels in the region, both in children and adults. This was brough about by "improving economic standards" which led to lifestyle changes and essentially more unhealthy diets.

"Food of low nutritional value is more easily and widely available due to its low cost and the introduction and adoption of western dietary habits," according to the Fitch report.