The Keto diest is nothing new, its basiclly the same thing as the Atkins diet that came out in the 70's. Almost every low carb diet is some sort of spin off of the Atkins diet.
That being said, you can lose weight on any low carb diet, you don't need to test your urine, if you stay below 20 grams of carbs per day your almost guaranteed to be in what they call Ketosis.
Most trainers these days will start their clients off on a low carb diet in the beginning because it is effective. However, eventually they stray away from it as you get closer to your goal weight.
If your excersise is mostly just lifting weight or not really doing any training, Keto works great. If your doing high intensity training, Keto doesn't work so well, your body will crash due not having enough carbs, I know this for a fact! Been there done that.
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