The Origin of the Term "Love Handles"
"Love handles" is known as a slang expression for the bulging flesh on the sides of the waist. Judging from how often it appears in consultation posts at Venus Clinic, the term "love handles" seems to be widely used in Korea these days. In the United States, however, the term is said to be used less commonly in general, and since its origin is slang with an embarrassing meaning, it may be better not to use it.

Dr. Klein, the originator of tumescent liposuction, wrote in his book "Tumescent Liposuction" that the region from the iliac crest to the costal margin is the male flank, and that it is not appropriate to use the slang term "love handles" for it.
In other words, the flank refers to the side of the body below the waist, and it would seem more correct to call only the rear portion of the flank "love handles," or, in women, the hips.
Below is a translation of the results that came up whensearching Wikipedia for "love handles" (originally translated into Korean for this article).
Etymology
Love handles is a colloquial or slang term for the layer of fat accumulated around the middle of a person's torso, particularly over the abdominal external oblique muscle, and visible from the side. The term was first used in the late 1960s, and the Historical Dictionary of American Slang defines it as fat protruding at the sides of the waist.
Both men and women seem to be concerned about love handles and sometimes even regard them as an undesirable body feature. Many products for removing love handles are on the market, but they are generally thought to have no real reducing effect; the best way to reduce them is to lose fat by being more active (through activities such as cardiovascular exercise and weight training) and consuming fewer calories.
These areas of excess skin around the waist were named "love handles" because, perhaps like a horse's reins, they can be grabbed by a partner during sexual intercourse, much as animals grab or bite protruding skin on a partner's neck or body when tangling or mating.
Use in the media
In July 2007, The Washington Post ran an article simply titled "Love Handles," writing that whereas weight gain was once thought to be inherited from one's parents, a study showed that when a friend is obese, about 57% of people may become obese. In August of the same year, the British newspaper The Daily Telegraph ran an article under the headline "Nicolas Sarkozy's love handles airbrushed," claiming that a photo of French President Nicolas Sarkozy had been edited before publication in a magazine owned by his friend. In March 2008, CBS News also used the expression in an article titled "When Lions Get Love Handles," describing the difficulty of providing balanced diets to animals kept in zoos.
Synonyms
Love handles are also colloquially called a "spare tire" because of their tire-like bulge around the middle of the torso. Other synonyms include midriff bulge, muffin top, and belt overhang.

References
Names of the Hips, Buttocks, Thighs, Flanks, and Waist
[ Dr. Jung, Director, Venus Clinic ]