Self-conscious people may suck in their stomachs - but doing so can be unhealthy. Adam Taylor, Professor and Director of the Clinical Anatomy Learning Centre, Lancaster University, has explained that the habit can create abdominal imbalance and all sorts of problems. In an article, he explained: "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." He added: "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, with the belly button being pulled upwards. "Sucking the stomach in places greater pressure on the lower back and neck. This is because they now have to compensate for changes in core stability." Sign up to our free Indy100 weekly newsletter He also said it may lead to changes in breathing capacity, though said more research needs to be done, and said sucking in the abdomen also puts strain on the pelvic floor which could cause incontinence. Fortunately, hourglass syndrome is reversible through exercises that strengthen core muscles like planks or bridges, he explained. And he also said the condition develops over weeks of consistently sucking in the stomach. "So occasionally sucking the stomach muscles in is not likely to cause problems," he said. Who knew it could have so many bad effects? Have your say in our news democracy. Click the upvote icon at the top of the page to help raise this article through the indy100 rankings.