Fish is one of the lowest-calorie protein sources you can eat. Even the fattiest varieties come in well under most cuts of beef or pork, and lean white fish delivers as few as 70 to 80 calories per 3.5-ounce serving. The real answer, though, depends on the type of fish and how you cook it.
Lean Fish vs. Fatty Fish
Fish falls into two broad categories based on fat content, and the calorie gap between them is significant. Lean white fish like cod, tilapia, flounder, and sole contain fewer than 120 calories in a 3-ounce serving. Atlantic cod, for example, has just 82 calories per 100 grams with less than a gram of fat. These fish get almost all their calories from protein.
Fattier fish like salmon, mackerel, and herring carry more calories because of their higher oil content. A 3-ounce portion of salmon runs about 175 calories with 10 grams of fat, while Pacific mackerel comes in around 134 calories for the same serving size. That’s still modest compared to a similar portion of 80/20 ground beef, which typically exceeds 230 calories.
The extra calories in fatty fish come with a nutritional payoff. Atlantic mackerel provides about 2.5 grams of omega-3 fatty acids (EPA and DHA combined) per 100 grams. Farmed Atlantic salmon delivers around 1.8 grams. These are the same fats linked to heart health and reduced inflammation, and fatty fish is the richest dietary source available. So while salmon has roughly twice the calories of cod, those calories are doing more for your body.
Shellfish Is Even Leaner
If you’re counting calories closely, shellfish deserves a look. Shrimp, scallops, and lobster are extremely low in fat. A 100-gram serving of boiled or steamed scallops has about 137 calories, and much of that comes from protein with just over 6 grams of carbohydrates. Shrimp is similarly lean. These options give you a high protein-to-calorie ratio that’s hard to match with land-based proteins.
How Cooking Changes the Numbers
The way you prepare fish matters more than most people realize. Grilling or baking adds little to no extra fat, keeping the calorie count close to the raw value. Frying is a different story. During deep frying, fish absorbs oil and loses moisture, which dramatically increases fat content.
Research on rainbow trout found that fresh fillets contained about 3.4% fat, grilled fillets rose to roughly 6%, and fried fillets jumped to nearly 13%. That’s almost a fourfold increase in fat from frying compared to raw. The pattern holds across species: fried anchovy reached 23% fat content versus about 11% when grilled, and fried sea bass hit nearly 10% fat compared to 5% grilled. Breading adds even more calories on top of the oil absorption. A battered, deep-fried fish fillet can easily contain two to three times the calories of the same fish grilled or baked.
Canned Fish: Water vs. Oil
Canned tuna is one of the most common ways people eat fish, and the packing liquid creates a surprisingly large calorie difference. A 5-ounce can of tuna in water contains about 120 calories. The same size can packed in oil jumps to around 280 calories, more than double. Ounce for ounce, that’s 24 calories versus 56. If you’re choosing canned fish to keep calories low, water-packed is the clear winner. Oil-packed tuna does have a richer flavor and slightly more omega-3 retention, but the calorie cost is real.
Fish Keeps You Fuller, Too
Calorie counts only tell part of the story. Fish protein appears to be unusually filling compared to other animal proteins. A study published in the European Journal of Clinical Nutrition gave young men either a fish-based or beef-based lunch with identical calorie counts. At dinner that evening, the men who ate fish consumed 11% fewer calories, a statistically significant difference. Separate research using a satiety index found that fish protein ranked higher than beef steak, eggs, and nearly every other food tested for its ability to keep people feeling full.
This combination of low calorie density and high satiety makes fish particularly useful for weight management. You can eat a satisfying portion of grilled cod or tilapia for under 120 calories, and you’re less likely to overeat at your next meal.
Calorie Ranges at a Glance
- Cod (100g, raw): 82 calories, under 1g fat
- Tilapia (4 oz): 145 calories, 3g fat
- Scallops (100g, steamed): 137 calories, minimal fat
- Pacific mackerel (3 oz): 134 calories, 7g fat
- Salmon (3 oz): 175 calories, 10g fat
For comparison, 3 ounces of cooked chicken breast has roughly 140 calories, and a similar portion of lean ground beef runs about 215. Even the fattiest fish sits comfortably in the range of the leanest land-based meats, and most fish falls well below it.