What is up with this? Dirty looks from 'heavier' people?

There is a workout facility here at the office complex I work at--I go anywhere from 2-4 times a week on my lunch hour. In walking through the building area to get to the elevators to go downstairs I pass by some ladies who are ... heavy(ier). I'm not some skinny chick--at 32, I'm 5'6, 157lbs and wear between a size 11 and 12 (waist 31 jeans, juniors size 13). I have meat on my bones--I have a little bit of love handles and (blech) back flab...plus the pooch of having given birth to two children. The looks I get from these ladies are awful! I start walking by, they all look up and just glare, mean "die b***h, die!!!" looks at me! I've waved, I've said hello, etc to no avail. WTF is up with that? I'm starting to get high school flasbacks!!!