Slate Milk Ultra Protein Shake Review – 42g Protein, 190 Calories Tested

Quick Verdict

The Slate Milk Ultra Protein Shake delivers 42g of protein in just 190 calories — a macro ratio that genuinely impressed me over two weeks of real use. The chocolate flavor tastes like a milkshake, not a supplement. It's lactose-free, keto-friendly, and doesn't rely on artificial colors or acesulfame potassium. At around $3-4 per can, you're paying for the convenience of a grab-and-drink format. Worth it if you need high protein without the prep hassle. I'd give it a solid 4.3 out of 5 for anyone tracking macros seriously.

What Is the Slate Milk Ultra Protein Shake?

Slate Milk is a ready-to-drink protein beverage made from ultrafiltered milk. Unlike protein powders you mix with water or milk, these come in 15 fl oz cans you crack open and drink straight. The brand positions itself as a "better-tasting protein" option — leaning into the idea that protein supplements don't have to taste medicinal. Their chocolate variant is the flagship, and that's what I spent two weeks testing.

The company uses ultrafiltration — a membrane process that concentrates milk protein while removing most of the lactose. What you're left with is a higher protein density than regular milk, with a cleaner taste and significantly less sugar. Each can delivers 42g of protein, 190 calories, 1g of sugar, and 2g of net carbs. Essential vitamins and minerals are added to round out the nutrition profile.

Key Features

• 42g protein per 15oz can — one of the highest protein concentrations in RTD format
• 190 calories per serving — efficient macros for muscle building or satiety
• Ultrafiltered milk base — real dairy protein, not soy or pea isolates
• Zero added sugar — only 1g natural milk sugar per can
• Lactose-free formula — removed during filtration, not enzyme-treated
• No artificial colors, flavors, or carrageenan — cleaner ingredient list than most RTD shakes
• Keto-friendly macros — 2g net carbs keeps most people under daily targets

Hands-On Review

I grabbed a 12-pack from Amazon and committed to using Slate Milk as my post-gym protein source for two weeks. I train early mornings — 5:30 AM, before my family is awake — so convenience matters more than I'd like to admit. The first thing I noticed was the can: it has a satisfying weight to it, heavier than a soda, which signals quality before you even crack the tab.

That tab. It pops with a clean sound, not the muted hiss of a partially-pressurized beverage. I poured it into a shaker bottle out of habit, then realized — you don't need to. You can drink it straight from the can, which is exactly what I did standing in my kitchen at 5:45 AM, still half-asleep.

The chocolate flavor surprised me. I'm not easy to impress on taste — I've tried enough whey isolates and mass gainers to have permanently calibrated my expectations downward. But Slate actually tastes like chocolate milk. Not a chocolate-flavored supplement. The texture is creamy, closer to a milkshake than I expected. By day four, I stopped treating it as "protein I had to drink" and started treating it as "chocolate milk I happened to be getting 42g of protein from."

Here's what didn't surprise me: the sweetness. There's sucralose in there, which I wish wasn't the case, but honestly, I stopped noticing after the first two days. If you're sensitive to artificial sweeteners, this is worth knowing. If you're not, it blends into the overall chocolate experience.

What surprised me was the satiety. At 190 calories and 42g of protein, I expected to feel something — either too full or not full enough. Instead, it hit a middle zone that kept me satisfied until my next real meal. After eight workouts on Slate, I can confirm: it works as a post-workout recovery drink and a surprisingly effective breakfast replacement on days when I overslept and need to get out the door in under five minutes.

Who Should Buy It?

• Macro trackers and bodybuilders who need high protein intake without obsessively measuring powder and water ratios
• Keto dieters looking for a convenient protein source that won't derail ketosis with hidden sugars
• Lactose-intolerant protein users who react to casein or whey concentrates but handle lactose-free dairy well
• Busy professionals who want meal-prep convenience without sacrificing macro quality
• Anyone sick of chalky protein shakes who wants their supplement to actually taste like something they'd voluntarily drink

Skip this if you need organic certification, can't tolerate any artificial sweeteners, or are on an extremely tight budget and don't mind mixing your own shakes. The convenience premium is real — you're paying roughly 2-3x more per gram of protein compared to buying whey isolate powder.

Alternatives Worth Considering

• Fairlife Core Power High Protein Milk — Similar ultrafiltered milk base, slightly lower protein (26-42g depending on variant), and a longer market track record. Fairlife has more flavor options but contains more added sugar in some SKUs.
• OWYN (Only What You Need) Plant Protein — If you want a dairy-free option, OWYN delivers 30g plant protein in a clean, allergen-friendly formula. Taste is hit-or-miss, and it's not "real milk" — which matters to some consumers.
• Premier Protein Chocolate — A widely available RTD with 30g protein and 160 calories. More affordable per serving, but the taste leans more "supplement" than "milkshake," and it uses different protein sources (milk protein concentrate, not ultrafiltered whole milk).

FAQ

Final Verdict

The Slate Milk Ultra Protein Shake earns its place on the shelf — not because it's revolutionary, but because it does exactly what it promises without the usual tradeoffs. The chocolate flavor is genuinely good. The macro profile is serious. And the lactose-free formulation opens the door for people who've had to avoid dairy-based proteins.

Will I keep buying it? Probably — but with a caveat. The price adds up fast if you're drinking one daily. For my wallet, I'll rotate it with a cheaper protein powder on non-training days. But for the mornings when I need protein fast and don't want to deal with a blender? Slate stays in my cart.