I drink a 20oz bottle of Gatorade every day only when i go to the gym, is this harmful? What about the colouring agents in the drink, are they harmful in any way?

If you're drinking Gatorade before you work out at the gym it is not harmful for you at all.  The only real concern from drinking too much Gatorade is the sugar in it.  If you're working out while drinking Gatorade you'll burn that sugar off so there's no concern about gaining unwanted weight.  That being said, you may find that if you switch to water your workouts will produce better results.

The coloring agents in Gatorade will cause no harm at all.  Coloring agents are dyes, they may dye your system a certain color, but other than perhaps giving you a scare in the bathroom they are perfectly harmless.

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