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Summary: Find the whey protein powders with the least calories per serving (where a serving = 40g protein). Whey protein powder is an incredibly low-calorie source of protein, but here's a ranking of the absolute lowest calorie shakes anyway.
Is it worth worrying about calories in whey protein powder?
Yes and no.
- Yes, because with whey protein you ideally want to get as much protein for as few calories as possible. If a powder has a lot of calories, it probably contains a bunch of extra stuff in it (e.g. extra carbs/sugars) that you don't want.
- No, because whey protein powders are very similar these days. I wouldn't worry if one shake has an extra 10kcal or so than another. The difference is negligible.
If you're absolutely balls-to-the-walls strict about your calorie intake, then maybe you'll care about such tiny numbers of calories. However, 99% of people looking to build lean muscle or cut fat aren't in this category. Even if you're cutting and aiming for 2,000kcal/day – a relatively low amount – the extra 10kcal here and there isn't going to touch the sides.
As long as you're getting around 100kcal for every 20g serving of protein I wouldn't worry. All things being equal, I'd be more concerned about how good my whey protein tastes.
Whey protein supplement calorie benchmarks.
Here's how many calories you should be expecting to get from your different sized whey protein shakes.
| Protein | Calories | Note |
|---|---|---|
| 20g | 100 kcal | A small protein shake (~1 scoop). |
| 40g | 200 kcal | A large protein shake (~2 scoops). |
Most whey powders hover around the 100kcal for every 20g of protein. So if you find a tub of whey protein with much more than 100kcal in every 20g worth of protein you should be wary (or it's probably not whey protein – it could be casein or a blend instead, which both tend to have more calories).
Whey protein powder calories compared to whole food.
Here's a table that highlights how many calories come with every 1g of protein you get from different whole foods.
| Food | Calories per 1g Protein | Calories per 20g of Protein |
|---|---|---|
| Protein Powder (ON Gold Standard Whey) | 4.9 kcal | 97 kcal |
| Chicken Breast | 5.3 kcal | 106 kcal |
| Tinned Tuna | 5.3 kcal | 106 kcal |
| Turkey Breast | 6.1 kcal | 122 kcal |
| Steak | 7.6 kcal | 152 kcal |
| Lean Mince (21% Fat) | 9.4 kcal | 188 kcal |
| Soybeans | 10.2 kcal | 204 kcal |
| Eggs | 11.0 kcal | 220 kcal |
| Cheddar Cheese | 16.1 kcal | 322 kcal |
| Whole Milk (100ml) | 18.3 kcal | 366 kcal |
| Peanut Butter | 24.2 kcal | 484 kcal |
1g of protein on its own is 4 kcal, no matter where it comes from. This table just shows how many calories you have to take in of each food to get each 1g of protein, so the added presence of carbs and fats in each food increase the calories for every 1g of protein you get to over 4kcal (1g carbs = 7kcal, 1g fat = 9kcal).
Whey protein supplements deliver the most amount of protein for the lowest amount of calories compared to actual food like meat and fish. This is why whey protein is so good for building lean muscle or cutting (losing fat), as you can keep your protein intake high without over doing it on the calories.
Do not replace actual food with whey protein shakes. Just because it delivers the fewest calories per 1g of protein it doesn't mean you can throw proper food out of the window. That would be horrendous, as whey protein does not have all the essential nutrients that proper meat and vegetables will give you. Whey protein powder is called a supplement – and not a replacement – for a reason.
Useful links.
- Calorie and macronutrient guide for building muscle – Incredible post that outlines how many calories you need in your diet to build muscle and how much protein to take in with that.
- Calories in protein, carbs and fat – Just a quick guide to how many calories there are in 1g of each macronutrient.