A 3-ounce serving of cooked ahi (yellowfin) tuna contains about 25 grams of protein and only 110 calories. Raw, it provides roughly 23 grams of protein per 100 grams. That makes ahi tuna one of the most protein-dense foods available, with 89% of its calories coming from protein alone.
Protein by Serving Size
The protein you get from ahi tuna depends on how much you eat and whether it’s cooked. Raw ahi delivers about 23.4 grams of protein per 100 grams. Cooking concentrates the protein slightly because heat drives out moisture, so a cooked 3-ounce portion comes in around 25 grams. A typical restaurant-style seared ahi steak weighs 5 to 6 ounces, which puts you in the range of 40 to 50 grams of protein in a single piece of fish.
For a quick reference:
- 3 oz cooked: ~25 g protein, 110 calories
- 4 oz cooked: ~33 g protein, 147 calories
- 6 oz cooked (typical steak): ~50 g protein, 220 calories
How Ahi Tuna Compares to Chicken Breast
Chicken breast is the go-to protein benchmark, so the comparison is worth spelling out. A 3-ounce serving of roasted, skinless chicken breast has about 27 grams of protein and 140 calories. Ahi tuna has slightly less protein per serving (25 grams) but also fewer calories (110), which actually gives it a better protein-to-calorie ratio. In chicken breast, 73% of calories come from protein. In ahi tuna, that number is 89%.
If your goal is to maximize protein while keeping calories low, ahi tuna has a slight edge. If you care more about total grams of protein per meal regardless of calories, chicken breast wins by a small margin. In practice, the difference is minor enough that either one works well as a lean protein source.
What Else You Get Besides Protein
Ahi tuna is extremely lean, carrying only about 1 gram of fat per 3-ounce serving. But the fat it does contain is disproportionately valuable. A 100-gram portion of yellowfin provides roughly 150 to 230 milligrams of EPA and DHA, the omega-3 fatty acids linked to heart and brain health. The recommended daily intake for those two fatty acids combined is 250 milligrams, so a single serving of ahi gets you 60 to 92% of the way there. The range depends on where the fish was caught: Pacific-sourced yellowfin tends to have the highest omega-3 levels, followed by Indian Ocean and then Atlantic fish.
Ahi tuna is also a strong source of selenium, niacin, vitamin B6, and vitamin B12, all nutrients that support energy metabolism and immune function.
Does Cooking Method Affect the Protein?
Cooking doesn’t destroy the protein in ahi tuna in any meaningful way. Heat causes muscle proteins to change shape (which is why the fish firms up and turns opaque), but your body digests and absorbs those proteins just the same. What cooking does change is the weight of the fish. Higher-heat methods like grilling and pan-frying shrink the fillet more than gentle techniques like searing or sous-vide, because they push out more water. A fillet that starts at 6 ounces raw might weigh closer to 5 ounces after grilling.
This matters for tracking. If you weigh your tuna raw but look up the nutrition for cooked tuna, you’ll slightly undercount your protein. The simplest approach: weigh it raw and use raw nutrition data, or weigh it cooked and use cooked data. Don’t mix the two.
Mercury and How Often You Can Eat It
The FDA classifies yellowfin tuna as a “Good Choice,” its middle tier for mercury. That’s better than bigeye tuna, which lands in the “Choices to Avoid” category due to the highest mercury levels, and slightly below canned light tuna (skipjack), which qualifies as a “Best Choice.” For most adults, eating yellowfin tuna a few times per week is reasonable.
The guidelines are stricter for pregnant or breastfeeding women: one serving (4 ounces) per week from the “Good Choices” list, or two to three servings from the “Best Choices” list. For children, the FDA recommends two servings per week from the lowest-mercury options, with portion sizes scaled by age, starting at 1 ounce for toddlers and reaching 4 ounces by age 11.
If you eat ahi tuna primarily for its protein content and want to eat it frequently, rotating in lower-mercury fish like salmon, sardines, or pollock lets you keep the protein intake high without accumulating mercury over time.