Core Viewpoint - The "fat pack bone" body type, which appears slim but has excessive fat and low muscle content, is gaining popularity among young people, yet it poses significant health risks [1][2][5]. Group 1: Definition and Characteristics - The "fat pack bone" refers to a body type that looks thin but has an excess of fat and a deficiency in muscle mass, often characterized by normal or low body weight but a noticeable layer of soft fat when pinched [2][5]. - Individuals with this body type typically exhibit abdominal obesity, which can be easily assessed by pinching the abdominal or upper arm fat [4][5]. Group 2: Health Risks - This body type is classified as "hidden obesity," where individuals may have normal weight but elevated body fat percentage, leading to higher health risks compared to simple obesity [5][6]. - The excess fat and low muscle content associated with the "fat pack bone" can increase the likelihood of hypertension, hyperlipidemia, osteoporosis, and even cognitive decline, indicating a more severe health risk than traditional obesity [6]. Group 3: Causes and Contributing Factors - Unscientific weight loss methods have been identified as a common cause of developing the "fat pack bone" body type, particularly among patients in clinical settings [7]. - Long-term lack of strength training, insufficient sleep, and high stress levels can disrupt hormone balance, inhibit muscle synthesis, and lead to fat accumulation, contributing to this body type [8]. Group 4: Weight Management and Recommendations - Experts suggest that the "fat pack bone" is a signal of metabolic crisis and should be taken seriously, recommending medical evaluation and scientific interventions to increase muscle and reduce fat for a healthier body composition [11]. - Weight management strategies that involve weight loss often result in muscle loss alongside fat loss, leading to a higher body fat percentage upon weight regain, especially if low-carb or high-protein diets are adopted without adequate resistance training [10].