Protein powders have become an increasingly popular supplement among athletes, bodybuilders, and anyone looking to increase their protein intake. With so many different types of protein powders on the market, many wonder which option provides the most protein with the least amount of calories.
When choosing a protein powder, calories are an important consideration for those aiming to lose weight or maintain a caloric deficit. The major protein powder varieties – whey, casein, egg, soy, rice, pea, and hemp – can range quite significantly in calories per serving. Whey tends to be one of the most popular protein powders due to its high protein content and rapid absorption rate, but it is not necessarily the lowest calorie option.
This article will compare the calorie content in different protein powder varieties and brands to determine which options provide the most protein with the least amount of calories.
Whey Protein Powder
Whey protein powder is one of the most commonly used protein supplements among athletes and bodybuilders. Whey is a byproduct of cheese production and contains high levels of branched-chain amino acids, which help stimulate muscle protein synthesis. This makes whey an effective option for building muscle mass.
The two main types of whey protein are:
Whey Protein Concentrate
Whey protein concentrate contains low levels of fat and carbohydrates. It typically provides around 70-80% protein by weight. The rest is made up of lactose and minerals.
On average, a 25g serving of whey protein concentrate contains around:
- 100 calories
- 20g protein
- 3g carbohydrates
- 1-2g fat
So in terms of calories, whey protein concentrate is a mid-range option. It provides around 4 calories per gram of protein.
Whey Protein Isolate
Whey isolate is a more purified form that contains 90% or higher protein content. The filtration process removes most of the lactose, carbs, and fat, leaving virtually zero grams of sugar.
A 25g serving of whey isolate averages around:
- 90-100 calories
- 22-24g protein
- 1-3g carbs
- 0-1g fat
With just 3-4 calories per gram of protein, whey isolate is one of the leanest protein powder options.
So in summary, whey protein isolate contains slightly fewer calories and more protein compared to whey concentrate. But whey products in general provide a good balance of high protein with moderate calories.
Casein Protein Powder
Casein is the other major dairy-based protein found in milk. During cheese production, casein proteins coagulate to form the solids, while whey remains in the liquid.
Like whey, casein provides all the essential amino acids needed to stimulate muscle growth. But it digests and absorbs at a slower rate, making it less ideal for post-workout recovery. Casein is more often used as a bedtime protein source to provide sustained release of amino acids overnight.
The calorie content of casein protein is comparable to whey:
- 100 calories per 25g serving
- 20-24g protein
- 1-2g carbs
- 1-3g fat
So casein also contains around 4 calories per gram of protein, similar to whey concentrate. This makes it a moderately low-calorie protein option.
Egg Protein Powder
Egg protein powder is made from pure egg whites and contains no fat or cholesterol. Since whole eggs average around 6g protein each, it takes approximately 40 egg whites to make a 25g serving of egg protein powder.
Egg protein is rich in leucine and provides the highest concentration of branched-chain amino acids after whey. It also digests slower than whey, making it less suitable for post-workout.
A typical 25g serving of egg white protein powder provides:
- 100 calories
- 22-25g protein
- 0g carbs
- 0g fat
With only 4 calories per gram of protein, egg white protein has virtually identical calories and protein to whey concentrate and casein.
The main downside is that egg protein has less research on its muscle building effects compared to whey and casein protein. But for those looking to cut calories, it can be an excellent high protein, low-fat option.
Soy Protein Powder
Soy protein comes from defatted soybean flakes and contains all the essential amino acids needed for muscle synthesis. It has traditionally been used as a vegetarian or vegan alternative to whey protein.
The protein content of soy powders ranges from 50-90%, with more refined “isolate” versions containing 90% protein or higher.
A 25g serving of soy protein powder averages around:
- 100 calories
- 22g protein
- 4g carbs
- 1-3g fat
Similar to the previous options, soy protein contains 4 calories per gram of protein. It provides comparable protein to whey and casein with slightly higher carbs.
The main drawback is soy has a lower leucine content, which may reduce its ability to stimulate muscle protein synthesis compared to animal-based proteins. But as a plant-based, low-calorie protein source, soy remains a viable option.
Rice Protein Powder
Rice protein is extracted from brown rice and often used by those who cannot tolerate dairy or soy protein. Although rice itself is low in protein, processing methods can isolate the proteins into a supplemental powder form.
Compared to previous options, rice protein is lower in the amino acid lysine. To compensate, rice protein powders are often blended with pea protein to provide a complementary amino acid profile.
On its own, a 25g serving of rice protein typically provides:
- 100 calories
- 22g protein
- 2-3g carbs
- 0-2g fat
Rice protein matches the 100 calorie and 4 calories per gram of protein benchmark shared by the other major protein powders. The main limitation is its less studied muscle building effects, but for strictly calories, rice protein can be considered moderately low.
Pea Protein Powder
Pea protein has surged in popularity in recent years as a vegan alternative to dairy-based protein. It is extracted from yellow split peas and contains high levels of iron, arginine, and branched-chain amino acids.
Like rice protein, pea protein is low in the amino acid methionine. Combining rice and pea protein provides an amino acid profile similar to whey protein.
A 25g dose of pea protein powder typically provides:
- 100 calories
- 22g protein
- 2-4g carbs
- 1-2g fat
With 100 calories and 4 calories per gram of protein, pea protein matches whey and casein for calorie content and protein density. The slightly higher carbs make it a moderately low-calorie choice.
Hemp Protein Powder
Hemp protein powder is extracted from hemp seeds and offers a complete, plant-based protein source. Like pea and rice protein, it is not as high in leucine compared to the dairy proteins.
A 25g serving of hemp protein contains:
- 100-120 calories
- 15g protein
- 7-8g carbs
- 5-7g fat
With 6-8 calories per gram of protein, hemp protein is higher in calories compared to other vegan protein powders. It also provides significantly less protein per serving.
Hemp can be used in combination with pea or rice protein to improve the amino acid profile. But on its own, the high calorie and carbohydrate content make it a less optimal choice for those looking to restrict calories.
Comparing Lowest Calorie Protein Powders
To summarize the key points:
- Whey protein isolate, egg white protein, and soy protein isolate are the leanest at around 4 calories per gram of protein
- Whey concentrate, casein, rice protein, and pea protein follow closely behind at 4 calories per gram
- Hemp protein is highest at over 6 calories per gram of protein
The table below compares the calorie and protein content in different protein powders more closely:
| Protein Powder | Calories (per 25g serving) | Protein (per 25g serving) | Calories per gram of protein |
|---|---|---|---|
| Whey Protein Isolate | 90-100 | 22-24g | 3-4 |
| Egg White Protein | 100 | 22-25g | 4 |
| Soy Protein Isolate | 100 | 22g | 4 |
| Whey Protein Concentrate | 100 | 20g | 4 |
| Casein Protein | 100 | 20-24g | 4 |
| Rice Protein | 100 | 22g | 4 |
| Pea Protein | 100 | 22g | 4 |
| Hemp Protein | 100-120 | 15g | 6-8 |
As shown, whey protein isolate, egg white protein, and soy protein isolate have the lowest calories per protein and provide around 22-25g of protein per 100 calorie serving.
Hemp protein is highest at over 6 calories per protein gram and only 15g of protein per serving.
For the majority of protein powders, calories run approximately 4 calories per gram of protein. So protein content becomes the next important factor for maximizing protein with minimal calories.
Conclusion
When evaluating the lowest calorie protein powders, the main options that rise to the top are:
Whey Protein Isolate
With 90-100 calories and 22-24g of protein per 25g serving, whey isolate is hard to beat in terms of protein-to-calorie ratio. It provides 3-4 calories per protein gram. Whey isolate offers the highest quality complete protein source with the lowest calories.
Egg White Protein
Nearly identical to whey isolate, egg white protein contains 100 calories and 22-25g protein per 25g serving, or 4 calories per protein gram. Egg protein provides an animal-based complete protein equivalent to whey.
Soy Protein Isolate
Matching whey and egg white protein, soy isolate also provides 22g protein and only 4 calories per gram of protein. It offers a suitable vegan alternative for low calorie, high quality complete protein intake.
While other protein powders contain slightly more calories per protein gram, whey isolate, egg white protein, and soy isolate stand at the top for maximal protein with minimal calories. Sticking to a 100 calorie serving with at least 22g of protein provides an optimal protein boost with approximately a quarter of the calories of most protein-rich foods.
So in summary, if your goal is strictly to add protein while cutting calories, these three isolated proteins offer the most efficient protein-to-calorie ratio.
