Skinny trends - all unrealistic - have emerged in social media in recent years.
They can be brushed off as quirky challenges.
But as more children and youth take to these unrealistic body images and aspire to an idealistic concept of beauty, more may fall prey to a negative body image.
"These 'thinspo' trends thrive dangerously on impressionable young women exposed to social media and, as a result, encourage body dissatisfaction," said Dr Christina Low, a general practitioner with Singapore Medical Group's SMG Medical. "Thinspo" is derived from "thinspiration", a play on "thin" and "inspiration".
THE BELLY BUTTON CHALLENGE
Men and women reach their arms around their backs to touch their belly buttons, to show off their supposedly small waists.
The challenge is said to have originated from the Chinese microblogging site Weibo.
Dr Low: This can be easily done if one has a relatively small waist and flexible shoulders.
It is barely a gauge of fitness or health, as the shoulders possess a greater motion range than other joints in the body.
THE COLLARBONE CHALLENGE
Women balance stacks of coins in the groove of their collarbones.
The belief is that the thinner you are, the more pronounced your collarbone will be, and the more coins you can fit in its groove.
Dr Low: This challenge has been around for years, although its popularity received a boost from the belly button challenge.
Many women look to celebrities like Angelina Jolie, Nicole Richie and Keira Knightley who have prominent clavicles, but they do not realise that all three women have different body structures.
Some women can be curvaceous with a prominent clavicle, while others can be very thin without an obvious collarbone.
THE BIKINI BRIDGE TREND
Women post pictures of the gap between their bikini bottom and their hip bones when lying down.
It started as a hoax on social media last year but went viral.
Dr Low: This trend is similar to the collarbone challenge.
The presence of a gap depends on the structure of the hip bones.
Having a bikini bridge does not necessarily mean a person is skinny, nor does it relate to a person's health and fitness levels.
THE THIGH GAP CRAZE
Women with a gap between their inner thighs when they stand with their feet pressed together are considered slim and beautiful.
Dr Low: Thigh gaps can be achieved through extensive exercise. But it is an unrealistic fitness goal. Having such a gap does not mean you are skinny, but it means that you have a body structure that allows for it. There are no health benefits to having a thigh gap.