Ian Marber, born 1963, is a nutrition therapist, well-known author and one of the founders of The Food Doctor, developing the brand from its inception in 1999 until his departure in December 2011... (wikipedia)
This supplies its energy steadily so you don't get a surge of blood sugar, which is then stored as fat.
A snack now prevents your blood sugar dropping.
It may give you a short term boost, but it's quickly followed by a dip in energy, with anxiety and irritability.