Until the age of 11, Tucker was a generally happy - if overweight - little girl and initially the diet was no cause for concern.
But what started out as a harmless exercise in self improvement spiralled into full blown anorexia, trapping Tucker and her family in an eight year battle with each other, mental health services and the illness.
Using a combination of diarised chapters, dramatic ''scenes'' and the occasional checklist, she takes you inside her mind and her experiences.
And not only does she write about the years of starvation, she also shares the most shameful thing an anorexic can admit to: the snapping of self control that catapulted her into 12 months of bulimia from which she is only now recovering.
Although the book provides an eloquent insight into thoughts, feelings and events that are simultaneously unique to the author and shared by anybody who has travelled down the same road, I have to preface my recommendation with a word of warning.
The title refers to what it means to be in recovery, the way in which the physical ''wellness'' precedes the emotional, an ongoing process of learning to become more than a Thin identity inside a Not Thin body.
As a former anorexic myself, I found it profoundly unsettling. It brought back too vivid memories; the constant hunger and constant fatigue, days full of lies, deception and manipulation, the numbing, bone deep cold, the ever present and remorseless battle between the pain of starvation and the anorexic Voice.
But even a decade into recovery I also found myself tempted by that Voice's siren call. Although Tucker is careful not to document weights or calorie counts, the book contains many other triggers.
There are the familiar rituals of bone counting and body checks - can you run the circle between your thumb and forefinger all the way up your arm? See the floor between your thighs? - that are the physical measures of ''accomplishment''.
There, too, is the competition with fellow anorexics over who is most ''successful'' (i.e. sickest; she does a lovely take on Monty Python's ''poverty'' sketch in which medical complications take the place of material deprivation).
And, most haunting of all, her descriptions of the spiritual and emotional purity that accompanies the physical emptiness.
This caveat aside, I would thoroughly recommend The Time In Between for anybody watching someone they care about disappear into anorexia's depths.
Although she can offer no specific answers - her turning point, as was mine, was a matter of the right person at the right time - it will provide a valuable insight into the stranger in front of you and a reminder that the real person is still somewhere inside.
There is nothing lonelier than being trapped with the demons inside your own head, and knowing somebody else understands even a little of that battle may be more help than you could ever realise.
Cushla McKinney is a Dunedin scientist.
