It is actually not hocus pocus at all.
What the alkaline diet is is basically avoidance of acidic foods. It is a nonsense to suggest that that eating alkaline foods will change the pH of your body but eating a diet in which acidic food features highly will most assuredly make you sick.
Ask anyone who has gout.
And gall stones.
And inflammation.
And osteoperosis.
And arthritis.
The western diet is high in Acid, low pH. It tastes nice. Think sugar and alcohol. Phosphoric acid is added to fizzy drinks by the ship load to make them taste better.
The reason I know this is because I embarked on this road back in 2011. I am now in far better condition now than I was then. One of the first things I noticed aside from the weight loss and the general well being is the absence of pain in my knees.