After linking loneliness to coldness and heaviness to importance, researchers at Radboud University Nijmegen in the Netherlands now suggest that when a person is in love, then even plain water tastes sweeter.
"We always say love is sweet. We thought let's see whether this it true," study researcher Kai Qin Chan, a doctoral candidate, was quoted as saying on livescience.com.
The fact that even water tastes sweeter when people think about love reveals that the emotion is not acting on the taste receptors on the tongue - making them more sensitive to sugar.
"There's no sugar in the water, after all. Instead, the effect must arise from the brain's processing of the taste information," added Chan.
Chan and his colleagues felt that embodied metaphors develop only after a lot of experience.
After surveying students at the National University of Singapore to be sure that they were aware of the 'love is sweet' and 'jealousy is bitter' metaphor, Chan conducted three experiments with 197 of them.
In the first two studies, researchers asked students to write about an experience either with romantic love or with jealousy, or about a neutral topic.
Next, scientists had the students taste either Ribena Pastilles - a sweet-and-sour gummy candy - or Meiji Morinaga bittersweet chocolates.
After tasting the candies, the students ranked the treats' sweetness, bitterness and sourness.
Those who had written about love ranked both candies as sweeter than those who had written about jealousy or a neutral topic.
Next, the researchers repeated the study, but this time asking 93 new students to sample distilled water instead of candy.
Researchers told the students the water was a new drink product and asked them to rate its sweetness, bitterness and sourness.
Again, love made the water taste sweeter - even though it had no real taste at all, said the study.
Jealousy did not affect the water's taste.
The linkage of love with the physical experience of sweetness may go back to infancy, Chan said.
Babies start their lives drinking breast milk or formula, both of which are sweet, and may learn to associate that taste with their mother's love, he added in the paper published in the journal Emotion.