Replace or reduce sugar in milk?

So, there's no method to get sugar out of milk, as far as I know. You can look for milk products where some of the sugar is used up (fermented, like Chris H mentioned), but this will significantly change taste and texture - sugar is a major part of what milk is, fats and sugars and proteins, and you're removing most of the actual substance.

You're likely to do better with an unsweetened nut milk or rice milk, especially if you make your own so you can tweak to taste. These may have more fats, depending on your choice of recipe, but will likely have sugar closer to your desired range

One thing you might try, if you're really determined, is to dilute your milk (maybe up to half) and add artificial sweeteners. You'll still get some of the flavor components from the added milk, and some sweetening to make up the difference in taste, but there will be less sugar because the actual amount of milk is less. Hopefully the added artificial sweetener might make it taste less watery, but maybe add just a half a pinch of salt if it still tastes too thin. in the end, ~6g sugar per cup, I guess?

Another possibility is to use unflavored whey powder to flavor the diluting water (again, probably no more than half of your "milk"), then adding artificial sweetener to taste. The whey should have some of the flavors from the proteins in milk, and at least from the powder I checked it doesn't have much of the sugar or fat you're objecting to. It might help the diluted milk taste less watery. ~7g sugar, because I think the whey powder has a gram and a half per serving.

Final possibility I thought of - you can maybe grab some creamer powder and use that to flavor your diluted milk (again, not more than half and sweeten to taste). Or even use it on its own, if the flavor works for you. The amount of sugar isn't stated, but it has to be under 1g because that's all the carbs there are per serving - though it does add a half gram of fat back in.

Lactose free milk usually contains 11.5-12% sugars! The less sugary is Barambah Organic but I am talking about Australia. I look for the less sugary full fat and I skim it at home by heating it to boiling point and leaving it to cool down then getting off the fat solidified on top. I save the cream for cakes, pastry made at home!

It seems only industrial processes can separate the sugars out of milk so the best seems to be to reconstitute milk at home and use allulose to recover the sweetness. Allulose is a sugar very similar to glucose that humans don’t metabolize. Tastes great, apparently bakes great, almost zero calories.

So.. I make my own milk as follows. The salts are just what I have on hand.. a more careful approach would more closely mimic true ‘milk ash’ (see http://www.milkfacts.info/Nutrition%20Facts/Nutrient%20Content.htm).

1 gallon keto-milk:

• 4000ml water
• 4cups plain protein, 50-80% caesin, remainder whey. Personally use 50% for simplicity of ordering ingredients.
• 1 cup heavy cream, preferably grass-fed for flavor profile. e.g. Naked protein or BulkSupplements.
• 1/2 cup allulose
• 16x 125mg/50mg/50mg magnesium/potassium/taurine caps, NOW brand. or equivalent, or custom salt blend.
• 2 tsp table salt
• 2 tsp buttermilk (optional. seems to improve flavor profile a little)

Add everything but cream, mix as little as possible to remove lumps using stick blender. (A tall narrow vessel helps to concentrate the lumps together for mixing). Then lightly mix in cream.

Voila. Keto milk that’s pretty close to original. Costs $10-$15 gallon depending on the protein used. Perhaps could be made at $8/gal with some finessing.

Tastes pretty darn good on its own, makes a great ice-coffee and goes great with Magic Spoon brand keto-cereal. I haven't tried baking with it yet.

I am not affiliated with any brands.. just reporting my personal experience.