New Delhi, April 3 -- Kissing is not only a fun expression of love and affection - it also burns calories and strengthens the immune system. And remember - it is not allowed to kiss women in public on a Sunday in Michigan. Here are some interesting facts about kissing. (Also Read | Do you get triggered in your relationship? Here are the 4 most common reasons)

1. A normal kiss burns 6.4 calories per minute. A passionate kiss can burn up to 20 calories per minute. That's even more than swimming, which burns 12 calories in one minute, just like jumping rope.

2. Today, an average kiss lasts more than 12 seconds. In the 1980s, couples came up for air sooner than that: back then an average kiss lasted a mere 5.5 seconds.

3. Public kissing is...