Quick Scoop: Rib flare usually happens when the lower ribs sit or move outward more than normal, often because of posture, breathing patterns, weak abdominal control, pregnancy/postpartum changes, or spinal shape issues like scoliosis. It can be a movement/posture pattern, not just a fixed body shape, and it’s often linked with an arched low back or poor core coordination.

Common causes

  • Poor posture , especially an extended lower back or anterior pelvic tilt, can make the ribs look more flared.
  • Breathing mechanics , like relying too much on chest breathing instead of diaphragm-driven breathing, can keep the ribs lifted.
  • Weak abdominal muscles can reduce the body’s ability to pull the rib cage down and inward.
  • Pregnancy and postpartum changes can alter ribcage position and core mechanics.
  • Genetics or connective tissue traits may make some people more prone to it.
  • Stress and high tension patterns may contribute through altered breathing and posture.
  • Scoliosis or other spinal alignment issues can cause one side of the rib cage to protrude more.

What it can feel like

Rib flare may be mostly cosmetic, but it can also affect breathing, core stability, and lower-back comfort. Some sources note it can go along with disrupted diaphragm and abdominal coordination.

When to get checked

If rib flare is new, painful, one-sided, worsening, or linked with shortness of breath, chest pain, or a known spinal condition , it’s worth seeing a clinician or physical therapist. A quick in-person assessment can help tell whether it’s posture-related or something structural.

Bottom line

In most cases, rib flare is caused by a mix of posture, breathing, and core control , not one single issue. If you want, I can also give you a simple self-check or a few safe exercises that are commonly used to improve it.