Skin tags are very common. About 25 percent of people will develop skin tags, usually starting after the age of 50. Skin tags are more common among people wit diabetes as well as people who are overweight or obese — conditions that often go together.
The friction created by skin rubbing against skin, a side effect of being overweight, is what causes skin tags in certain people, and explains why skin tags often grow in body folds.
Repetitive friction and wearing tight clothes may contribute to skin tags in people who are overweight. According to a medical paper written by dermatologists in Spain, an obese patient, whose job required repeating lifting of her arms, developed a pattern of skin tags along her bra straps from the constant friction. Avoiding tight clothing if you are overweight is suggested.