Declining BMI and possible associations with changing perceptions of masculinity in Japanese young males

Puberty is a critical phase, typically beginning between the ages of 8 and 13 in girls and 9 and 14 in boys, though timing can vary based on genetics, environmental factors, and overall health. This period is characterized by the development of secondary sexual characteristics and the attainment of reproductive potential. Endocrine changes underpin puberty, with hormonal surges of Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) instigated by Gonadotropin-Releasing Hormone (GnRH)...

Aging and its effect on bone remodeling is the most common cause of bone disorders. In young and healthy people, bone deposition and resorption happen at an equal rate to maintain optimal bone health.
Bone deposition is also affected by the levels of sex hormones like estrogen and testosterone that promote osteoblast activity and bone matrix synthesis. When the level of these hormones decreases due to aging, it causes a reduction in bone deposition. As a result, bone resorption by osteoclasts...

Anorexia nervosa is a complex and severe eating disorder characterized by an intense fear of weight gain, an unrelenting pursuit of thinness, and a distorted body image. It often leads to dangerously low body weight relative to an individual's age and height. This disorder is marked by significant physical and psychological consequences, making it one of the most life-threatening psychiatric illnesses.
Symptoms and Physical Effects
Individuals with anorexia nervosa commonly exhibit extreme...

Social-emotional experiences and cultural influences play significant roles in shaping gender development. During middle childhood, from ages 6 to 11, peer groups become dominant in reinforcing gender norms. Children in this age group often align with same-gender peer groups, which actively encourage behaviors that conform to traditional gender roles. For instance, boys may be discouraged from engaging in activities perceived as feminine, reinforcing culturally dictated norms about masculinity...

One influential perspective on what motivates people's behavior is detailed in Tory Higgin's self-discrepancy theory (Higgins, 1987). He proposed that people hold disagreeing internal representations of themselves that lead to different emotional states.  

Adolescents from ethnic minority backgrounds face a multifaceted journey in forming their identities, shaped by the intersections of cultural expectations and personal exploration. For these adolescents, identity formation involves not only typical developmental challenges but also navigating the perceptions and attitudes of the majority culture. As they grow, adolescents in ethnic minority groups often become increasingly aware of stereotypes, social biases, and discrimination, all of which...