This is the most accurate post I’ve seen on tumblr
You are standing wrong. I say this as a massage therapist who works with people’s bodies all day: women are taught to stand wrong. Since the 50’s, pictures of women have been posed with their feet tilted to the side, knees locked to minimize the natural knobby shape of the knee, and sway-backed to stick their asses out for “perkiness” or whatever.
That is bad for your everything, and causes weakness in the core muscles which tighten and flatten the stomach.
The cure: feet pointing directly forward, put your hand on your tailbone. Tilt your pelvis until the tailbone is straight up and down. This will cause your knees to bend very slightly. It makes a huge difference for back and knee pain, and will make your tummy flatter with no sit-ups or working out at all.