Introduction: Obesity and overweight are important public health problems. Mindfulness can promote healthier living and dietary habits, which might support weight loss. This study aimed to evaluate the relationship between eating awareness and body mass index (BMI) and body composition in adults. Methods: This cross-sectional analytical study was conducted with 446 volunteers. The heights, weights, and waist circumferences of the participants were measured, and bioelectrical impedance analyses were performed. A sociodemographic information form prepared by the researchers and the Turkish version of the Mindful Eating Questionnaire (MEQ) were administered to the volunteers. Results: In this study, 31.2% (n = 139) of the participants were overweight and 46.9% (n = 209) were obese. There was no statistically significant relationship between gender and BMI. The total mean MEQ score was found to be 88.26 ± 13.3 (53–144). The awareness scores of women of normal weight were statistically significantly higher than those of women with obesity (p = 0.001). There was no difference between BMI categories and awareness scores among male participants. While participants with obesity had higher scores for eating disinhibition, their eating control, eating discipline, and interference scores were lower than those of participants with normal weight (p < 0.001). A weak statistically significant correlation was found between the awareness subdimension of the scale and the ages, BMIs, waist circumferences, and body fat rates of the participants. Conclusion: It was observed that mindful eating was lower in women with overweight and obesity than that in women with normal weight. We believe that it is important to increase awareness of eating in order to protect against the diseases caused by obesity and for a healthy life.