Factors that can affect your health and body size

Several factors can influence your body size and health beyond just your BMI. These factors are why BMI should always be interpreted as part of a broader health assessment.

Genetics: Your genes can affect how and where your body stores fat.

Lifestyle: Diet, physical activity, sleep and stress all play a role.

Certain health conditions or medications: Medical conditions and some medications can impact weight and stored fat.

Age and sex: Body composition often changes over time and can vary between men and women.

Race and ethnicity: Research shows that BMI doesn’t reflect body composition the same way across all groups. Factors like muscle mass, fat distribution and metabolic conditions can differ based on ethnicity. Cultural perceptions of weight and access to care may also shape someone’s experience with weight management.

BMI is a helpful screening tool, but it should always be interpreted as part of a broader health assessment—one that accounts for who you are as a whole person.