Final answer:
Factors such as energy balance, nutrition, and genetics determine if a person is underweight; however, aspects like race or gender, which do not influence energy balance or nutrition, would not directly determine an individual's underweight status.
Step-by-step explanation:
Factors such as genetics, caloric intake, levels of physical activity, and access to healthy food options play pivotal roles in determining a person's body weight. However, when addressing the specific question, we must consider aspects that are unrelated to body composition. Factors such as race or gender, would not directly determine if a person is underweight, as being underweight is primarily related to an individual's energy balance and nutritional status.
Defining Undernutrition
An insufficient intake of nutritious foods leading to undernutrition is a primary factor for being underweight. Adults are considered underweight if their body mass index (BMI) is less than 18.5 kg/m². Conversely, aspects like race and gender, similar to how they do not affect individual political opinions or greatly influence a person's socialization in sociology, do not directly determine one's body mass or nutritional status.