A single raw blue mussel contains roughly 10 to 15 calories, depending on its size. Per 100 grams of raw mussel meat, the count is about 73 calories. That makes mussels one of the lowest-calorie protein sources you can eat, comparable to egg whites but with a far more interesting nutrient profile.
Calories by Serving Size
Most people don’t eat mussels one at a time, so here’s how the calories scale. A standard restaurant portion of steamed mussels is roughly one pound in the shell, which yields about 150 to 170 grams of edible meat. That puts a typical serving somewhere around 110 to 125 calories. A three-ounce (85-gram) cooked portion, the standard used on nutrition labels, comes in at about 70 to 75 calories.
Cooking method matters, but not as much as what you cook them in. Steamed mussels on their own add very few calories beyond what the raw meat contains. A white wine and garlic broth might add 30 to 50 calories per serving. A cream-based sauce or butter broth can easily double or triple the calorie count of the dish. If you’re tracking calories, the mussels themselves are almost never the problem. It’s the bread you dip in the broth.
Why Mussels Pack So Much Protein
The calorie breakdown for mussels is striking. Of those 73 calories per 100 grams, nearly all of it comes from protein: 13.8 grams worth. Fat contributes just 2 grams, and carbohydrates are essentially zero. That gives mussels one of the highest protein-to-calorie ratios of any whole food. You’d need to eat nearly twice as many calories of chicken breast to get the same amount of protein per gram of food.
The protein in mussels is also high quality. Marine bivalves contain a strong amino acid profile, meaning the protein your body absorbs is readily usable for muscle repair and other functions. For anyone looking to increase protein intake without adding significant calories, mussels are an unusually efficient choice.
Nutrients That Set Mussels Apart
Calories tell you how much energy a food provides, but they say nothing about what else comes along for the ride. This is where mussels genuinely stand out. A single three-ounce serving of steamed blue mussels delivers 850 percent of the daily value for vitamin B12. That’s not a typo. No other common food comes close to that concentration. B12 is essential for nerve function, red blood cell production, and energy metabolism, and many people (especially those who eat little red meat) run low on it.
The same serving provides 33 percent of the daily value for iron and 28 percent for zinc. Iron from shellfish is the heme form, which your body absorbs significantly more efficiently than the iron found in plant foods like spinach or lentils. Zinc supports immune function and wound healing. Mussels also contain meaningful amounts of omega-3 fatty acids, particularly EPA and DHA, the same heart-healthy fats that make salmon a nutritional star. The concentrations are lower than in fatty fish, but for a food this low in calories and total fat, the omega-3 content is notable.
Mercury and Safety
One reason people hesitate around seafood is mercury. Mussels are among the safest options available. According to FDA testing data, mussels and other bivalves like clams (0.009 ppm) and oysters (0.012 ppm) sit at the very bottom of the mercury scale, far below fish like tuna or swordfish. Because mussels are filter feeders that eat phytoplankton rather than other fish, they don’t accumulate mercury up the food chain the way predatory species do. You can eat mussels multiple times per week without approaching any mercury concern.
How Mussels Compare to Other Shellfish
- Mussels vs. shrimp: Shrimp run slightly higher at about 85 calories per 100 grams, with comparable protein. Mussels win on B12 and iron by a wide margin.
- Mussels vs. oysters: Oysters are similar in calories (roughly 68 per 100 grams raw) and also rich in zinc and B12, though they tend to be significantly more expensive per serving.
- Mussels vs. clams: Clams are close nutritional cousins, with about 74 calories per 100 grams and high iron content. The two are nearly interchangeable from a calorie standpoint.
Among all common proteins, mussels occupy a rare sweet spot: very low in calories, very high in protein, loaded with micronutrients, and extremely low in mercury. They’re also one of the most environmentally sustainable animal proteins available, since farmed mussels actually filter and clean the water they grow in rather than depleting resources.
Keeping the Calorie Count Low When Cooking
Steaming mussels in white wine, garlic, and herbs is the classic low-calorie preparation. A pound of mussels cooked this way typically stays under 200 calories total for the entire bowl. Substituting broth for wine works just as well. Adding a squeeze of lemon and fresh parsley at the end keeps things bright without adding calories.
Preparations to watch out for include mussels in cream sauces (moules marinières made with heavy cream), deep-fried mussels, and mussels gratinéed with butter and breadcrumbs. These can push a serving past 400 or 500 calories. None of that is inherently bad, but if you’re choosing mussels specifically for their low calorie density, the cooking method is where most of the extra calories sneak in.