He has a green, orange and red list. You only eat green if you are insulin resistant, have metabolic syndrome, are diabetic or are wanting to lose weight. In this range you want to keep your net carbs (carbs minus fibre) in the range of between 20-50 grams per day (that's between 10-25 castle lites

if that's all you have the whole day) which will induce ketosis and your body will use fat as energy, everyone is different. You can include some on the orange list which includes many healthy food's provided you stay in this daily carb range or are on a maintenance diet. The red list is a no go or reserved for treats but it is all the food's high in sugar and simple carbohydrates (less fibre) anyway that shouldn't be on any diet list.
The carbs on the orange list are still valuable but have either more sugar or less fibre so in order to stay in Ketosis and burn fat as energy you should have less the more insulin resistant you are.
Noakes website realmealrevolution explains this in more detail.