Is Whey Protein Keto? Carbs, Types and Lactose Explained
Is whey protein keto? Whey protein powder can fit a keto diet, but check the label, because the carbs depend on the type and the flavour. Two Optimum Nutrition powders sold by UK retailers list 1.3g and 1.6g of carbohydrate per scoop. The British Dietetic Association (BDA) puts a very low carb (ketogenic) diet at 20–50g of carbohydrate a day. Whey comes from milk, so it isn't suitable for anyone with a milk allergy, and some powders contain lactose.
At a glance
- 1.3gcarbs in a 30g scoop of Gold Standard 100% Isolate, Chocolate (pack label)
- 1.6gcarbs in a 31g scoop of Gold Standard 100% Whey, Double Rich Chocolate (pack label)
- 90%minimum protein (dry basis) for whey protein isolate, under the ADPI standard
- 50gthe protein reference intake for an average adult on UK food labels
On this page
This guide is about whey protein powder itself: what it is, how many carbs it has, how isolate and concentrate differ, and what to look for on the label if you're eating keto. Whey is also in several of our own baking mixes, so we've included those too.
Is whey protein keto?
It can be. A ketogenic diet is defined by how much carbohydrate you eat, and the BDA's low carb diets fact sheet puts a very low carb (ketogenic) diet at 20–50g of carbohydrate a day. A scoop of whey protein powder uses only a small part of that, though the amount depends on the powder.
Take two powders from Optimum Nutrition, which we checked on the brand's UK site and two UK retailers:
- Gold Standard 100% Isolate, Chocolate: 1.3g of carbohydrate in a 30g scoop, of which 0.3g is sugars, with 25g of protein.
- Gold Standard 100% Whey, Double Rich Chocolate: 1.6g of carbohydrate in a 31g scoop, of which 1.0g is sugars, with 24g of protein.
Against the lower end of the BDA's range, 20g a day, one scoop is 6.5% or 8% of the day's carbs. What you mix it with counts as well: CoFID 2021, the UK's official food composition data, lists semi-skimmed milk at 4.7g of carbohydrate per 100g, all of it lactose.
These are two products, not every powder. Flavours and sweeteners change the figures, so go by the label on your tub.
What whey protein is
The American Dairy Products Institute (ADPI), a dairy industry body that publishes standards for dairy ingredients, defines whey as the liquid obtained from cheese manufacture. It defines whey protein as the protein in milk that remains in the water phase after the casein precipitates. Our guide to whether cheese is keto covers the cheese side.
Whey protein ingredients are made by removing enough of the non-protein parts of whey for the dried product to reach a set protein level. The ADPI says whey protein concentrate is made by physical separation techniques such as membrane filtration, and whey protein isolate by membrane filtration and/or ion exchange.
Whey isolate vs concentrate
The ADPI sets separate standards for the two types. Under them, whey protein concentrate (WPC) must contain at least 25% protein, and whey protein isolate (WPI) at least 90% protein on a dry basis. In the ADPI's typical figures, the more protein, the less lactose:
| Ingredient | Protein | Lactose |
|---|---|---|
| WPC 34 | 34–36% | 48–55% |
| WPC 80 | 80–82%* | 4–10% |
| WPI (isolate) | 90–92%* | 0.5–1% |
Typical values from the ADPI's whey protein concentrate and whey protein isolate standards (v4.0, effective July 2023). *Dry basis; the other figures are as sold. These are specifications for the ingredient, before any flavourings or sweeteners are added.
The ADPI says the most common commercial concentrates are WPC 34 and WPC 80. Retail powders can mix types: the ingredients list for Gold Standard 100% Whey names whey protein isolate, whey protein concentrate and hydrolysed whey protein isolate, while Gold Standard 100% Isolate names whey protein isolate and hydrolysed whey protein isolate. Neither label says which grade of concentrate or isolate it uses, so the nutrition table is the better guide to carbs.
Carbs in whey protein powder
Here are the label figures for the two powders, per 100g and per scoop. We checked each on Optimum Nutrition's UK site and two UK retailers on 3 November 2026, and the figures matched.
| Per 100g | Carbs | Sugars | Protein |
|---|---|---|---|
| Isolate, Chocolate | 4.5g | 1.1g | 83g |
| 100% Whey, Double Rich Chocolate | 5.3g | 3.2g | 76g |
Optimum Nutrition Gold Standard pack labels. Isolate: Optimum Nutrition UK, Holland & Barrett and London Supplements. 100% Whey: Optimum Nutrition UK, Holland & Barrett and Sainsbury's.
Per scoop, the isolate has 1.3g of carbohydrate and 110kcal in 30g, and the 100% Whey has 1.6g of carbohydrate and 116kcal in 31g. The 100% Whey also lists 2.3g of fibre per 100g (0.7g per scoop) on Optimum Nutrition's site and at Sainsbury's. On UK labels, fibre is listed separately from carbohydrate, so you don't need to take it away from the carbohydrate figure.
Both are sweetened: the isolate with sucralose, and the 100% Whey with sucralose and acesulfame K. If a powder uses a polyol such as erythritol, UK law counts it as carbohydrate, and the label may show it on an "of which polyols" line. That's the line we take away to work out net carbs on our own products.
Whey vs other protein foods
For comparison, these are CoFID 2021's figures for some everyday protein foods, per 100g:
| Per 100g | Protein | Carbs |
|---|---|---|
| Chicken breast, grilled, no skin | 32.0g | 0.0g |
| Cheddar, English | 25.4g | 0.1g |
| Tuna, canned in brine, drained | 24.9g | 0.0g |
| Eggs, whole, raw | 12.6g | Trace |
| Greek style yoghurt, plain | 5.7g | 4.8g |
| Semi-skimmed milk | 3.5g | 4.7g |
CoFID 2021, sheet 1.3 Proximates, food codes 18-323, 12-346, 16-416, 12-937, 12-555 and 12-313. CoFID has no entry for whey or whey protein powder (all 15 sheets searched).
The BDA's sport and exercise fact sheet gives portions that each contain about 20g of protein, including 1 small chicken breast (75g cooked weight), 3 medium eggs, half a 450g pot of Greek yoghurt and 1 pint of semi-skimmed milk. A 30g scoop of the isolate above has 25g. For more on dairy carbs, see our guide to whether yoghurt is keto.
On how much protein people need, the same BDA fact sheet gives 0.75g per kg of body weight a day for people who don't exercise, and about 1.4–2.0g per kg a day for athletes in strength and endurance sports. It says that in most cases, as long as energy needs are met, a balanced diet should provide enough protein to meet these higher needs. On supplements, it says they "will not compensate for poor food choices but may be helpful in certain situations", and to consult a registered practitioner if you're considering one.
Lactose and milk allergy
The NHS describes lactose as "a sugar found in dairy products", and lists "diet and protein shakes" among the processed foods that can contain lactose. In the ADPI's figures, a WPC 34 ingredient is about half lactose, while an isolate has 0.5–1%. A label's sugars figure includes any lactose, but doesn't show it separately.
The NHS says lactose intolerance is when you get symptoms, such as tummy pain, after eating food containing lactose. It also says it's important not to cut foods out of your diet without the advice of a GP or a dietitian.
A milk allergy is different. The NHS lists cows' milk among the most common allergic foods, and says that if you have a food allergy, you will not be able to eat the food you're allergic to, including foods where you're allergic to any of the ingredients. Whey is a milk protein. Under UK food labelling law, milk is one of 14 listed allergens, and both Optimum Nutrition labels show whey as milk.
How to read a whey protein label
The NHS says that ingredients must be listed in descending order of weight, and that pre-packed foods must highlight allergens in bold. When you compare whey powders for keto, these are the parts of the label to check:
- Carbohydrate per serving. Compare it with your daily limit, and check the serving size, because scoops vary (30g and 31g in the two powders above).
- Sugars and polyols. Sugars are part of the carbohydrate figure. If there's an "of which polyols" line, that's part of it too.
- The first ingredient. In both powders above, the whey protein blend comes first, at 93% of the 100% Whey and 94% of the isolate.
- Allergens. Look for milk in bold, plus any "may contain" line. Both Optimum Nutrition powders list soy lecithin, and their brand pages say they may contain traces of gluten, egg, nuts and peanuts.
Baking with whey on keto
Optimum Nutrition suggests adding a serving of its isolate to smoothies, protein balls, muffins, porridge or other meals. Closer to home, whey is one of the ingredients in several of our baking mixes:
- Keto Pancake Mix: based on almond flour, coconut flour and whey protein isolate, and sweetened with our erythritol and stevia blend. Its product page gives 4g of carbohydrate per cooked pancake, of which 2g is polyols, for 2g of net carbs. Our guide to crêpes vs pancakes explains the style of pancake it makes.
- Keto Chocolate Cake Mix: lists erythritol, almond flour, cocoa powder and organic coconut flour ahead of whey protein. Its product page gives 12g of carbohydrate per 41g baked slice, of which 11g is polyols, for 1g of net carbs.
- Scone and pizza base mixes: our Keto Scone Mix lists whey protein, and our Keto Pizza Base Mix lists whey powder.
All of these contain milk and almonds, so they aren't suitable if you're allergic to either. For the flours used alongside whey in these mixes, see our guides to almond flour on keto and flaxseed on keto. Free delivery on orders over £30.
Speak to your GP, diabetes nurse or a registered dietitian before you make big changes to your diet. This is especially important if you have diabetes and take insulin or other medicines that can cause hypos, or take SGLT2 inhibitors, as your medication may need to change. The same goes if you're pregnant, breastfeeding or have a history of eating disorders.
Key takeaways
- Whey protein can fit keto, at 1.3g and 1.6g of carbs per scoop for the two powders we checked, against the BDA's 20–50g a day.
- Isolate has the least lactose. Under the ADPI standards, an isolate is at least 90% protein (dry basis), with typical lactose of 0.5–1%.
- Whey is a milk protein, so it isn't suitable for anyone with a milk allergy.
- The label is what counts. Check carbohydrate per serving, any polyols, the serving size and the allergens.
Frequently asked questions
Is whey protein keto?
It can be. Two Optimum Nutrition powders sold in the UK list 1.3g and 1.6g of carbohydrate per scoop, and the BDA puts a very low carb (ketogenic) diet at 20–50g of carbs a day. Flavours and sweeteners change the figures, so check the carbohydrate per serving on your own tub.
Which has fewer carbs, whey isolate or concentrate?
Under the ADPI standards, an isolate is at least 90% protein on a dry basis, with typical lactose of 0.5–1%, while WPC 80 typically has 4–10% lactose and WPC 34 48–55%. In finished powders the gap can be small: the isolate and blend we checked list 4.5g and 5.3g of carbs per 100g.
Does whey protein contain lactose?
It can. The NHS describes lactose as a sugar found in dairy products, and lists diet and protein shakes among the processed foods that can contain it. In the ADPI's figures, whey protein isolate has 0.5–1% lactose and WPC 34 has 48–55%. On a label, any lactose is counted in the sugars figure.
How much protein is in a scoop of whey?
The two Optimum Nutrition powders we checked list 25g of protein in a 30g scoop of the isolate and 24g in a 31g scoop of the 100% Whey. The reference intake for protein on UK food labels is 50g a day for an average adult, so one scoop is about half of that.
Can you bake with whey protein on keto?
Yes. Whey is in several of our baking mixes: our Keto Pancake Mix uses whey protein isolate with almond and coconut flour, and our Keto Chocolate Cake Mix uses whey protein. Optimum Nutrition suggests adding its isolate to smoothies, protein balls, muffins and porridge. Remember that whey contains milk.
Sources
- Optimum Nutrition UK. Gold Standard 100% Isolate and Gold Standard 100% Whey (select Double Rich Chocolate): nutrition tables, ingredients, allergy advice, serving sizes, suggested use. Checked 3 November 2026.
- UK retailer listings, checked 3 November 2026: Holland & Barrett, Gold Standard 100% Isolate Chocolate and Gold Standard 100% Whey Double Rich Chocolate; London Supplements, Gold Standard 100% Isolate; Sainsbury's, Gold Standard 100% Whey Double Rich Chocolate.
- American Dairy Products Institute. Whey Protein Concentrate and Whey Protein Isolate standards, v4.0 (definitions of whey and whey protein, minimum protein, typical protein and lactose, production methods).
- British Dietetic Association. Low carb diets food fact sheet (20–50g of carbohydrate a day on a very low carb, ketogenic diet) and Sport and exercise food fact sheet (protein needs, 20g protein portions, supplements).
- NHS. Lactose intolerance (what lactose is, foods that can contain it, not cutting out foods without advice), Food allergy (most common allergic foods) and Food labels (ingredients order, allergens in bold). Checked 3 November 2026.
- Regulation (EU) No 1169/2011 on food information to consumers, as it applies in Great Britain: Annex I (definitions of carbohydrate, sugars, polyols and fibre), Annex II (milk as an allergen) and Annex XIII (protein reference intake of 50g).
- Public Health England / Food Standards Agency. Composition of Foods Integrated Dataset (CoFID) 2021: sheet 1.3 Proximates, food codes as listed under the table.
- Groovy Keto product pages: Keto Pancake Mix, Keto Chocolate Cake Mix, Keto Scone Mix and Keto Pizza Base Mix (ingredients, allergens, carbs and polyols per serving). Checked 3 November 2026.
