For the study published in the journal PLOS Medicine, the researhers analysed daily hospitalisation data covering almost 80 per cent of Brazil between 2000 and 2015.
They studied the link between daily mean temperatures and hospitalisation for undernourishment according to the International Classification of Diseases.
"The association between increased heat and hospitalisation for undernutrition was greatest for individuals aged over 80, and those 5 to 19 years," said the researchers from Monash University, Australia.
The researchers found that for every 1°C increase in daily mean temperature during the hot season, there was a 2.5 per cent increase in the number of hospitalisations for undernutrition.
"We estimated that 15.6 per cent of undernutrition hospitalisations could be attributed to heat exposure during the study period," said study's lead author Yuming Guo.
The study said that increased heat may cause illness through undernourishment in a number of ways: reducing appetites, provoking more alcohol consumption, reducing motivation or ability to shop and cook and exacerbate any undernutrition, resulting in hospitalisation.
"Climate change is one of the biggest threats to the reduction of hunger and undernutrition, especially in low and middle-income countries. It has been estimated that climate change will reduce global food availability by 3.2 per cent and thus cause about 30,000 underweight-related deaths by 2050," the report said.
"It is plausible to speculate that climate changes could not only increase the rate of undernutrition in the most affected areas of the globe, but at the same time, impair individuals' capacity to adapt to projected rises in temperature," said the researchers.
( With inputs from IANS )