With this in mind, we asked five of the world's elite fitness studios ... where their vanilla-flavored Protein Excellence Shake provides all the nutrients you need after an intense or moderate gym ...

Optimum Nutrition claims its Gold Standard 100 per cent Whey is the world’s “best-selling ... find they perform better in the gym if they ingest a protein shake 30-45 minutes beforehand.

A common way to boost intake of this important macronutrient is with supplements — but are protein shakes good for you? You've likely seen people drinking them at the gym or ads for them online.