One 100g piece of chocolate has about 550 calories

Calorie (abbreviated as cal), transliterated from the English Calorie, is defined as the amount of The amount of heat required to raise 1 gram of water by 1 degree Celsius; calorie is an energy unit that is still widely used in nutritional measurement and fitness manuals. The international standard energy unit is joule.

As the legal unit of food calories, joules are commonly used in Europe, while calories are used in the United States. Although the joule is the legal unit in mainland China and Taiwan, calories are still widely used in mainland China and Taiwan due to tradition.

Extended information:

The main component of chocolate is cocoa butter. The cocoa butter contains theobromine, which is toxic to many animals, but for humans, theobromine is a healthy food. It contains anti-sedative ingredients, so eating chocolate has the effects of lifting the spirit and enhancing excitement. Cocoa contains phenylethylamine, which is rumored to make people feel in love.

Reference: Baidu Encyclopedia-Calories