Probably the best way of turning a smoothie into a meal is to add rolled oats to it. Many breakfast type smoothies have oats in them for this very reason.
Oats are proven to help lower cholesterol and reduce bool pressure. They are also a great source of slow release energy – so help you keep going until lunch. Most people have oats in their cupboards so they are readily available and also cheap. So, what’s not to like.
If you want to be a bit more adventurous – you can also use any muesli, as these normally contain a good portion of oats – as well as nuts and dried fruits. All of which will work. If you don’t like the bits – then put the muesli in first with some liquid and whizz till smooth – then add the rest of the ingredients.
Oats are dry and will adsorb quite a lot of water … so you’ll have to add some extra liquids to compensate. Trial and error is the best way to judge this – as it all depends on what consistency you like.