Often suck your stomach in to look slimmer in pictures? It can lead to 'hourglass syndrome'

economictimes.indiatimes.com:

But certain health conditions and even unnecessarily tensing the muscles during your daily life can cause the abdominal muscles to become imbalanced. Over time, this can lead to a condition called "hourglass syndrome" — a detrimental change in the structure of the abdominal wall, which may cause a visible crease to form in the mid-abdomen. Not only that, but this change can also have a knock-on effect on the internal organs and other parts of the body if left untreated. There are four main causes of hourglass syndrome. All of them result in an imbalance in the function of the abdominal muscles. The first is due to certain congenital conditions (such as gastroschisis or omphacele) which cause the abdominal muscles to develop incorrectly, leading to muscle imbalances. Poor posture is another cause. This leads the spine to move away from its normal, s-shaped curvature, resulting in detrimental changes in the tension and function of the abdominal muscles, leading to imbalances. Pain in the abdomen (whether from stomach, liver or gallbladder problems) can also cause a person of voluntarily or involuntarily contract their abdominal muscles in order to reduce or avoid pain. But another surprising cause of hourglass syndrome may be body image issues, which are an increasing issue. People who may feel insecure in their body or who want a flat stomach may suck their stomach muscles to achieve this look.

When we suck our stomach in it causes our rectus abdominis (commonly referred to as our «six-pack» muscles) to contract. But since we tend to store more fat tissue in our lower abdomen, the muscles at the top of the stomach tend to be more active. This creates a fold or crease in the abdomen over a long period,