Do you think the trend "waist training" with waist cinchers are effective and mostly is it healthy?

Not healthy ! Not: Healthy! tight lacing (also called waist training or corset training) can cause shortness of breath, fainting; indigestion. This practice can decrease lung volume (requiring intercostal breathing). Relatively less use of lower lungs can lead to coughing. The liver is forced upward ; accessory lobes of the liver may form. Stomach volume is reduced ; the intestines are compressed. Not healthy!