<human>: Summarize the given text in a few sentences.

Since my girlfriend was introduced to my younger sister, they've always had a real sisterly relationship (even though they're not related). My sister was overweight for a very long time, and my girlfriend (who played soccer in college) served as an inspiration for her to lose weight.

But over the past year and a half, their relationship has gotten worse and worse.

Only a few noticeable things have happened during this time - My sister has lost a lot of weight and has become her high school's top female sprinter, which is quite an accomplishment. On the other hand, my girlfriend and I are hooked on a pastry shop that opened very close by, and so we've both put on a bit of weight (about 40 lbs each in the past year and a half). 

Anyway, my sister started wearing uber-trendy outfits that she was never comfortable in before, and my girlfriend actually gave her a lot of old clothes/outfits (everything from jeans and dresses to heels etc.)

As for us, my girlfriend is basically wearing yoga pants (which my sis makes fun of) and those suede Birkenstock slippers (Boston clogs?, my sister actually makes fun of them to my GF's face) and I'm wearing sweats a lot too now, which my sister also mocks. 

My sister and girlfriend are obviously not getting along like they used to. Sometimes, it feels like you can cut the tension in the room with a knife. 

AND - when we go to her track meets, she'll either act like she doesn't see us, or if we're in front of her friends, she'll actually make jokes about us.
<bot>: It seems like my sister doesn't care for me or my GF anymore, but all that's really changed over the past year and a half is our weights