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Is it love, or just lust? The answer, it turns out, might have to do with which part of our brain is being activated.

The study, published Wednesday in the Journal of Sexual Medicine, analyzed 20 studies related to the effects of sex and love on the body. The research included brain scans of people who viewed erotic photos, photos of their significant others, food and other pleasure triggers.

Two parts of the brain, the insula and the striatum, are responsible for tracking the way in which sexual desire develops into feelings of love, researchers said. Lust triggers parts of the brain that control pleasurable feelings, associated with sex and food, but love triggers parts of the brain associated with habits.

"We assign different language to love and sexual desire and addiction," said Jim Pfaus, a professor of psychology at Concordia University in Montreal and lead author of the study. "But really, they're all being processed in a similar place. When we see this, the idea of love at first sight probably isn't true. People are feeling desire."

The brain treats love like a habit that has been formed over time. So, after lust may come love, and those feelings of love move to different part of the brain that processes habits and reward patterns. The same brain pattern occurs when people become drug addicts.

"Habits usually get a bad reputation, but it's an important thing that the brain imposes," said Pfaus. "The change from desire to love is the bonding mechanism in relationships."

These brain mechanisms involve monogamy and connection in a variety of different kinds of relationships, experts said. It activates the need to defend the interests of one's children or lover, Pfaus said.

"So, really, drug addiction is an embellished expression of something perfectly normal," said Pfaus.

Pfaus said the research acts as a cornerstone for other research on the subject.

"This research speaks to evolution," said Pfaus. "And it could help understand addiction, love and other social neuroscience research."