What Is a Weak Jaw and How to Improve It Jawzrsize, LLC
23/09/2020· The face''s bone structure also changes with age, with the jaw''s angle increasing. This change causes reduced definition in the lower part of the face. Excess Weight. Accumulated fat in the lower face is a common cause of weak jaw. Even slight weight gain can reduce the appearance of the jawbone. Fat and skin from excess weight can make the jawline nearly invisible. Thumb Sucking.