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Of American-English origin, the plural noun love handles designates excess or unwanted fat at the waist.

In this phrase, the image is of the waist being held on to during sexual intercourse.

—Synonym: a spare tyre around the waistline.
—Cf. also the phrase to put on a bit of pudding.

These are, in chronological order, the earliest occurrences of the noun love handles that I have found:
—Note: The first two occurrences of love handles are from interviews of the U.S. actress, singer and dancer Mary Frances ‘Debbie’ Reynolds (1932-2016), who specified that it was an expression used by her father, Raymond Francis Reynolds:

1-: From the following paragraph, by the U.S. humorist and journalist Herb Caen (1916-1997), published in the San Francisco Chronicle (San Francisco, California, USA) of Thursday 22^nd September 1960 [page 25, column 1]:

FAMILY NOTE: Debbie Reynolds, I’m happy to discover, is also Frank and Earnest. While she was in town the other day to plug her new dress line, somebody asked her: “Is everybody in your family as slim as you?” “Not at all,” said Miss Debbie, right out. “My mother is—well—rather plump, but my dad likes her that way. He calls the excess ‘love handles.’ As a matter of fact, he’s always saying to me, ‘The trouble with you, Debbie, is you’ve got no love handles.’” So saying, she slipped off, tittering prettily.

2-: From an interview of Debbie Reynolds, by Wanda Hale, in the column Hollywood Visitor, published in the Daily News (New York City, New York, USA) of Monday 9^th November 1964 [page 42, column 2]—Harry Karl was Debbie Reynolds’s second husband:

“Another thing on my program when I get home is taking off five pounds I’ve gained, right here,” she said, placing a hand on each hip. “But I get no encouragement from my two men. Daddy says a woman should have curves, which he calls, in the idiom of the Southwest, love handles. Isn’t that sweet, love handles? Harry, too, likes curves. He says a skinny girl looks like a frame upon which a woman should be built.”

3-: From Club 15 Helps Teenage Girls Physically as Well as Mentally, by Celestine Sibley, published in The Atlanta Constitution (Atlanta, Georgia, USA) of Tuesday 21^st November 1967 [page 5, column 2]—Muriel Grossfeld (1940-2021) was a U.S. gymnast:

With today’s miniskirts hundreds of young girls yearn for firm thighs and hundreds of young girls have saggy thighs and wads of fat around the midriff, which Muriel learned they now call “love handles.”
“Show me,” I asked. And she obligingly grasped a handful of something around her waist.
“Is that you?” I asked.
The young Olympic star smilingly shook her head and opened her sweat suit and tried to accumulate a handful of flesh under her skin tight leotard. No luck. There was none to spare.

4-: From The Day (New London, Connecticut, USA) of Friday 5^th April 1968 [page 24, column 4]—here, love-handles is the name of a music band:

College To Have Songfest

NEW LONDON—Folk, barbershop, popular and contemporary tunes will be heard in a songfest at 7:30 tonight at Palmer Auditorium, Connecticut College.
The Footnotes from Princeton University, the Baker’s Dozen from Yale University, and the Love-Handles from Trinity College will join two Connecticut College groups, Conn Chords and the Schwiffs, in singing a variety of songs.
The guitar will provide the accompaniment for the Love-Handles and the Conn Chords.

5-: From the column Meandering Around Town, by Mary Metzger, published in the Casa Grande Dispatch (Casa Grande, Arizona, USA) of Wednesday 29^th October 1969 [page 5, column 1]:

Want to get rid of the blahs and the “love handles” (excess inches around the waist) at the same time? Drop in and see BONNIE (MRS. TED) NELSON at Woman’s World. She has a lively group of women who make losing inches a fun thing.

6-: From the column Reflections of a News Hen, by Maryon Allen, published in The Mobile Press Register (Mobile, Alabama, USA) of Sunday 3^rd May 1970 [page 16-D, column 3]:

I do want to tell you about something I like immeasurably, and that article is my exercise wheel. It is the greatest. This thing is made of tricycle looking rubber wheels placed on a rod with handle bars at the ends, and after getting on your knees, you push it out along the floor.
[…]
The exercise wheel is one of the few things on earth that will help you get rid of your “love handles”… you know, they are those things that hang over a man’s belt and over a girl’s girdle top. If you want to be unromantic you can call them rubber tires or just plain flab.