What is a healthy breakfast drink?

Porridge is low GI which is supposed to make you full for longer.

Coconut water             

Tea... If you like it... Perhaps, cocoa drink... 

Eat, what you want to eat.

Why not try a protein-powder based drink or smoothie ? 

I usually mix a few spoons of protein powder with almond/soy milk, coffee, and some water. 

You can find other recipes on the net. 

The 'Innocent' range have mixed juice smoothies that are quite nice.

Orange juice is healthy.

V-8 works, sometimes with worcestershire sauce or Tabasco. 

Fruit juice is very high in sugar.

In fact, a glass or orange juice has as much sugar as six oranges ... and none of the fiber that slows down absorption of sugar into your blood stream (the fiber is not in the pulp, but in the membranes that separate the segments from each other).

If you want to feel full longer, eat something that has protein in it.  Sugar boosts blood sugar quickly, but then your pancreas releases insulin to lower excessive blood sugar ... but ends up taking TOO much out.  Then your energy crashes.

What can you drink?  Maybe vegetable juice. But even there, you are not getting much protein .. there is protein in vegetables, but not much.

Whole grains, legumes, eggs, cheese, meats .... these are our common sources of protein.  I often have oatmeal (whole grain/protein) with raspberries (high fiber) and yogurt (protein and Calcium) for breakfast.  You cannot exactly drink it, though.

Simpler would be whole wheat toast with peanut butter or almond butter, and an orange (not orange juice).

I drink a V8 every morning. Sometimes I’ll add a little bit of Tabasco sauce if I want it spicy. You can add Worcestershire sauce, horseradish, Tabasco, salt, pepper, ice cubes, and turn it into an alcohol free Bloody Mary.