Sometimes locs can become thin at the roots. This can be for several reasons.
Hormones often dictate the thickness of hair on one’s head. As some people age, hair loss can be common. This is prevalent with biologically sexed males, but it can happen to anyone regardless of sex. Stress, diet and lifestyle also contribute to hormone levels.
Another common reason for thinned loc roots is overmaintenance. Some people retwist their locs too tightly or too frequently, and the constant scalp tension causes traction alopecia. Many people with locs think traction alopecia is only for people who abuse weaves or braids, but this is false! Traction alopecia can follow improper loc care as well.
If you suspect this may be the case for you, try to retwist your locs every two weeks at most frequent. Make sure the twists aren’t too tight on your head. Some people also freeform their roots for a couple months to plump them up.
Tightly styling your hair, pulling on it frequently, or wearing it in a ponytail can also contribute to the problem.
Other than reducing sources of scalp tension and eating right (taking vitamins, too!), there’s not much that can be done to combat natural hair thinning. To keep your shin locs from falling out, you can either permanently freeform the roots or combine the thin locs together to make thicker roots.