Iced coffee has the most calories, you know?

A new study by the World Cancer Research Fund (WCRF) found that iced coffee popular in summer is actually high in calories, with some iced coffee as high as 561 calories, equivalent to a dinner.

Most iced coffees have more than 200 calories and some have more than 450 calories, the BBC reported, citing WCRF data. Sugar, whole milk and cream are the driving forces behind the high calorie content of iced coffee, the foundation said.

Starbucks 'summer limited edition coffee, Blackberry Mocha Frappuccino, has 561 calories in a large cup, equivalent to a quarter of a woman's daily calories, according to WCRF research. Without the cream, it's 457 calories.

Studies also show that some iced coffees are still high in calories even when skim milk is used. For example, a nonfat mocha iced latte from European coffee chain Caffe Nero has 452 calories.

If you want coffee, it's best to opt for a diet coffee with skim or low-fat milk, and not too much cream or sweet fruit syrups, which are high in calories, said Dr. Thompson, director of the WCRF science program.