This is a Myth!
Resistance Trained Individuals (resistance trained = weight training 2-3x/wk for at least past 6 mths) need higher levels of protein intake, but more has been proposed to be detrimental. It has been commonly accepted that 1.4-2.0g/kg/d (day) is sufficient.
But what about beyond 2.0g/kg/d?
2 major studies by Antonio et al. suggest otherwise:
4.4g/kg/d & 3.4g/kg/d; both examining body composition.
30 & 48 healthy resistance trained men and women.
In the 4.4g/kg/d study groups were split into 1. Control Group & 2. High Protein Group for 8 weeks. Both groups were asked to maintain the same training and dietary habits (i.e. carbohydrates & fats). In the 3.4g/kg/d protocol similar groups emerged expect this time all participants completed a periodized split routine with heavy resistance.
1st study– NO adverse effects to a hypercaloric protein diet nor increase in body fat.
2nd study– NO adverse effects + the high protein group experienced higher decreases in fat mass & body fat %. Also the high protein group had greater performance gains in bench press, back squat, vertical jump, and pull-ups!
Consuming a high protein diet in conjunction with a heavy resistance training program improves body composition and performance gains!