Yes. They should be treated as a staple carb, not as a ‘free vegetable’. Sweet potatoes are actually higher in carbohydrate than normal potatoes (that shouldn’t be a surprise – the word ’sweet’ is a big clue). Sweet potatoes are 95% carb (5% protein) and normal potatoes are 92% carb.
They are not allowed in Phase 1, therefore. In Phase 2, they should form the basis of a carb meal and be eaten with other carbs e.g. veggie chilli or with low fat products, like low fat cottage cheese.

I do get questions like – what about parsnips and other root vegetables? Are they not the same as potatoes? The key points here are:

– Carrots, for example, contain 10g of carb per 100g and sweet potatoes have got 20g of carb per 100g. So, potatoes are in a different carb league amongst the root vegetables. (Please note that water content explains what seems like inconsistent numbers. When we say sweet potatoes are 95% carb, we mean, of the bit that is not water, 95% is carb i.e. there are 20g of carb and barely 1g of protein and the rest is water).

– The carb content of parsnips is almost as high as that of potatoes, but the quantities in which they are normally consumed are quite different. Whereas a baked potato can be 200g in weight, you are unlikely to serve yourself 200g of parsnips. If you were planning to have this quantity of parsnips, make sure you’re having a carb meal.