The book is a guide to healthy eating which educates the reader about what is doing your body good, and what ISN'T.
For those who enjoy carbohydrate with everything they eat, prepare yourself for some unwelcome revelations about what it is doing to your health. Unless you are performing an extremely active job, it is likely that your calorie intake is more than double that required to survive. Inevitably, the result of excess carbohydrate and fat is stored fat under your skin.
The GI or GL theory is well known, and Holford is the best exponent of it on the shelf. He goes into a lot of detail which is convincing enough to persuade you to alter the contents of your trolley next time you buy the groceries.
Follow the Holford theory, and watch your energy levels rise, reduce your periods of daily fatigue, and reduce the weight and size of your stored bodyfat.