Final answer:
Weight gain in middle age is not a psychological disorder, but it can be a health concern if it leads to obesity and related medical conditions.
Step-by-step explanation:
Weight gain in middle age is a common concern for many people. However, weight gain itself is not a psychological disorder. It can be a result of various factors such as changes in metabolism, lifestyle, or hormonal fluctuations. It is important to note that weight gain becomes a health concern when it leads to obesity, which is associated with several medical conditions including type 2 diabetes and heart disease.