Sugar is a major contributor to serious health problems such as obesity, diabetes and heart disease, yet consumption of the sweet additive has surged across the world in recent decades.

Hotter days could be one factor nudging people to grab cooling sugary drinks like soda and juice -- or a few scoops of ice cream, according to a study in the journal Nature Climate Change.

"Your environment definitely shapes what you eat and how you eat, and climate change is part of it -- it might have an adverse influence on your health," study co-author Duo Chan of the University of Southampton told AFP.

The team of UK-US researchers analysed data about the food bought by households in the United States between 2004 and 2019, then compared the purchases to the weather and other climate factors.

For every extra degree of Celsius within 12-30C, people consumed 0.70 grams of extra sugar a day, the modelling showed. People with lower incomes or less education tended to be most affected.

- Diets already altering -

Under "worst case" climate scenarios, the most disadvantaged groups could eat or drink as much as five extra grams of sugar daily by the end of the century, lead study author Pan He of Cardiff University told AFP.

The American Heart Association's daily recommendation for men is no more than 36 grams of added sugar -- around nine teaspoons' worth -- and 24 grams for women.

One can of soda contains around 40 grams of sugar.

Most Americans consume two to three times the recommended amount, the association says.

The increase in sugar consumption seen in the study levelled off when temperatures tipped over 30C. Chen guessed this was because people had already changed their diet by that time.

Duo said it might be "even worse news" that people were already altering their diets at lower, rather than extreme, temperatures.

The modelling also found that people bought fewer baked goods on hot days -- likely because they were choosing ice cream or other frozen desserts instead.

An unhealthy diet is one of the four main risk factors for diseases that are responsible for more than 70 percent of all deaths worldwide, according to the World Health Organization.