If you go to a regular grocery store you may have had the good fortune to come across protein bars and giant containers full of protein powder that are touted to give you a slim and toned body just by consuming it and doing nothing else. While inneffective alone, together with regular exercise they may produce results like the one you see on the package. 

And this may be where the connection originates from.

Various studies have the conclusion that consuming protein an hour after a workout improves muscle protein synthesis. The slim bod may also result from ingesting protein as two effects result from it: improved resting metabolism and increased satiety which means feeling fuller for longer and less calories being consumed as a result.

While the mainstay of gym-goers and gym rats what’s less known that it is equally, if not more, important for the elderly. After the age of 30 muscle mass density decreases 3% to 8% each decade which increases the risk for injury caused by falling over or tripping. Lesser appetite and hunger sense can also slowly reduce of amount of protein and other nutrients that the elderly recieve from their diet so those shakes and bars may be a good option as a high-density protein option.