Why is Seafood Low in Calories? A Deep Dive into Nutrition

December 11, 2025 •

3 min read

According to the Food and Drug Administration (FDA), a 3-ounce portion of many lean fish contains fewer than 100 calories. But what is it about the composition of fish and shellfish that makes seafood low in calories, and such an effective part of a weight management plan?. This article explores the science behind why seafood is a remarkably low-calorie food.

Quick Summary

An exploration of the nutritional properties that make seafood a low-calorie food. It covers its high protein, low fat, and omega-3 content, detailing how these factors contribute to satiety and weight control. The article also contrasts seafood with other proteins and addresses cooking methods.

Key Points

High-Quality Protein: Seafood is packed with lean, high-quality protein that boosts metabolism and increases feelings of fullness, helping to reduce overall calorie consumption.
Low Fat Content: Most seafood varieties are naturally low in fat, particularly saturated fat, which significantly lowers their overall calorie count compared to red meat and poultry.
Healthy Omega-3 Fats: While some fish are higher in fat, it is predominantly healthy omega-3 fatty acids, which benefit heart and brain health and can help manage weight.
Nutrient-Dense: Besides being low in calories, seafood is a rich source of vital nutrients, including B vitamins, vitamin D, selenium, and iodine.
Cooking Matters: Preparation methods like baking, steaming, and grilling keep calorie counts low. Frying or adding rich sauces can add significant calories.
Satiety Effect: Studies have shown that consuming fish protein can lead to a greater sense of fullness and lower subsequent meal calorie intake compared to other protein sources.

The Core Components: Protein and Fat

Seafood's low-calorie profile can be primarily attributed to its high protein and low fat content. Unlike many land-animal proteins, which are often marbled with fat, most seafood is exceptionally lean. Protein is a macronutrient that plays a critical role in weight management. It has a high thermic effect, meaning your body burns more calories digesting it compared to fats or carbohydrates. Furthermore, protein promotes satiety, helping you feel full for longer and reducing overall calorie intake.

The Role of High-Quality Protein

Seafood is a complete protein source, providing all the essential amino acids your body needs for muscle building and repair. The protein in seafood is also easier for the human body to digest because it contains less connective tissue than red meat and poultry. This makes it an excellent option for people who may have difficulty with digestion, such as the elderly. The satiating effect of seafood protein is particularly noteworthy; one study found that participants who ate a high-protein fish lunch consumed 11% fewer calories at dinner compared to those who had a beef lunch.

Understanding Seafood's Fat Content

While the low-fat content is a major reason why seafood is low in calories, it's important to differentiate between types of seafood. Lean white fish like cod, haddock, and flounder have very low-fat percentages, often less than 5%. Even fattier fish, such as salmon and mackerel, are still relatively low in fat compared to many cuts of red meat.

Lean fish: White, flaky fish with very little fat. Examples include cod, sole, and haddock.
Fatty fish: Contain more fat, but this is primarily healthy omega-3 fatty acids. Examples include salmon, mackerel, and herring.
Shellfish: Known for being incredibly low in fat and calories. Examples include shrimp, crab, and scallops.

The fat found in seafood is predominantly unsaturated, particularly the highly beneficial omega-3 fatty acids EPA and DHA. These healthy fats offer numerous health benefits, including supporting heart and brain health, and are a key reason why health organizations recommend incorporating seafood into your diet.

Comparing Seafood to Other Protein Sources

To illustrate the nutritional advantage of seafood, consider the following comparison table based on a 3-ounce (85-gram) cooked portion.


Protein Source	Approximate Calories (kcal)	Approximate Protein (g)	Approximate Fat (g)
Atlantic Cod	82	18	0.7
Cooked Shrimp	101	24	1.5
Atlantic Salmon	175	22	10.5
Chicken Breast (roasted)	165	31	3.6
Ground Beef (85% lean)	215	22	14

Note: Calorie and fat content can vary based on the specific species, preparation, and fat percentage.

As the table shows, lean fish and shellfish are among the lowest-calorie and lowest-fat protein options available. Even fatty fish like salmon, while higher in calories, provide significantly more healthy omega-3s than other animal proteins and are still more moderate in calories than fattier beef options.

The Impact of Preparation Methods

While seafood is inherently low in calories, its final calorie count can be dramatically altered by how it is prepared. Cooking methods that add significant amounts of oil, butter, or breading can quickly negate the natural low-calorie benefits. For instance, a 3-ounce serving of baked catfish contains about 122 calories, while the same portion battered and fried contains 195 calories.

Baking and Broiling: Uses dry heat to cook the seafood, often requiring minimal added fat.
Grilling: A fast, flavorful method that uses high, direct heat. A light brush of olive oil is usually all that is needed.
Steaming and Poaching: Gentle, moist-heat cooking that requires no added fat and preserves flavor and nutrients beautifully.
Sautéing: Using a small amount of healthy oil, such as extra-virgin olive oil, is a great option for adding flavor without excessive calories.

A Concluding Perspective on Sustainable Weight Management

In conclusion, seafood is a powerful ally for anyone focused on weight management. Its fundamental nutritional composition—high-quality, easily digestible protein and low-fat content—is the primary reason why seafood is low in calories. This unique combination helps control appetite, boosts metabolism, and provides essential nutrients that support overall health. By prioritizing simple, healthy preparation methods, you can maximize seafood's benefits without adding unnecessary calories. Incorporating a variety of fish and shellfish into a balanced diet, alongside regular exercise, offers a sustainable and delicious path to achieving your health and weight goals. To learn more about specific nutritional information for different species, consult trusted resources like the NOAA Fisheries website.

NOAA Fisheries

Frequently Asked Questions

While most seafood is relatively low in calories, there are variations. Lean white fish like cod and shellfish like shrimp are very low, while fattier fish like salmon contain more calories, but are also packed with heart-healthy omega-3s.

Yes, significantly. Healthy cooking methods like baking, grilling, and steaming keep calories low. Frying, breading, or adding rich, buttery sauces can dramatically increase the calorie count.

Seafood is excellent for weight loss due to its high protein and low-calorie content. The high protein promotes satiety, which helps in controlling appetite and reducing overall calorie intake.

The protein in seafood helps with weight management in two key ways: it boosts metabolism by requiring more energy to digest (high thermic effect) and it promotes a feeling of fullness that can prevent overeating.

Yes, omega-3s are very healthy polyunsaturated fats. While fat is more calorie-dense than protein, the health benefits of omega-3s—which include reducing inflammation and supporting metabolic function—make fatty fish a highly nutritious and still moderate-calorie choice.

Shellfish like shrimp, crab, and oysters are among the lowest-calorie seafood options available. They provide significant protein with minimal fat, making them an excellent choice for a low-calorie diet.

Yes, but it depends on the packing medium. Canned tuna packed in water is low in calories, whereas tuna packed in oil will have a higher fat and calorie content.