Major purpose of this study was to investigate the differences between three feeding regimes, namely ad libitum (AD), %20 restricted feeding based on ad libitum (RF) and fasting between 09.00 AM and 15.00 PM (NF), for Body Mass Index (BMI) and weight slopes and for percent fat content in broiler chickens. The data was collected from 60 Ross 308 line male and female chickens. BMI and weight slopes were calculated for each bird and were analyzed as data using ordinary least squares in addition to repeated measures analysis for acidity, dry matter and fat percent. The regression coefficient of first week BMI values on slopes was -0.276 +/- 0.023 (P<0.001). The AD group had the steepest slopes followed by RF and the NF group when the slopes were calculated using BMI values (P<0.01) or when the slopes were calculated using weight (P<0.01). The regression coefficient of first week weight on the slopes was 0.602 +/- 0.267 (P=0.024) and that of first week's BMI on weight slopes was -5.58 +/- 3.5 (P=0.679). Differences between breast and rump were significant in acidity and dry matter (P=0.00). Overall, the AD group meat had more fat percentage compared to the other groups and the differences were significant (P<0.05). These suggest that heavy animals tend to have higher BMI values and fat percentage, especially with ad libitum feeding.