Assuming the study is taking adults on a 2500 calorie diet down to 1600, an extra 300 calories from metabolic effects is not insignificant but the majority of v

Assuming the study is taking adults on a 2500 calorie diet down to 1600, an extra 300 calories from metabolic effects is not insignificant but the majority of variance is explained from a simple model of calories where fat calories ~ carb calories ~ protein calories. If you want to lose weight then simply counting calories and eating less is an effective strategy.