Nutritional comparison: protein, calories, and fat

If you compare plain, cooked chicken breast with canned light tuna in water, both are very high in protein and relatively low in calories. Chicken breast is typically a little leaner and more calorie-efficient per serving, while tuna often has a slightly stronger protein-to-calorie ratio depending on the type. The exact numbers vary by species, cut, and preparation.

Chicken is often the better choice if your main goal is a simple, low-fat protein source. Tuna can be just as practical for protein, especially in salads, sandwiches, or meal prep, but the health value drops fast if it’s packed in oil, served in heavy mayo, or turned into a high-sodium dish.

Tuna’s advantage: omega-3 fats and heart health

One reason tuna may be considered healthier than chicken in some situations is its omega-3 content. Fatty fish are well known for providing EPA and DHA, which support heart health and may help reduce triglycerides. Tuna generally has more omega-3s than chicken, especially if you compare it to skinless chicken breast.

That said, not all tuna is equally rich in omega-3s. Fresh tuna steaks and some darker tuna cuts usually have more fat than canned light tuna. Chicken has some nutritional strengths too, including B vitamins and, depending on the cut, less saturated fat than many red meats.

The main caution with tuna: mercury exposure

The biggest downside to tuna is mercury. Larger, longer-lived tuna species tend to accumulate more mercury than chicken, which is one reason chicken is usually the safer everyday protein choice. This matters especially for pregnant people, breastfeeding people, young children, and anyone eating fish frequently.

Lower-mercury tuna options, such as canned light tuna, are generally safer than albacore or bigeye tuna, but portion size still matters. If you eat tuna often, it’s smart to vary your protein sources instead of relying on tuna every day.

Which is healthier for your goals?

For most people, chicken breast is the more consistently healthy default choice because it’s lean, affordable, versatile, and low in mercury. It’s especially useful if you want a simple high-protein food for fat loss, muscle gain, or meal planning.

Tuna may be the better choice when you want more omega-3s, a shelf-stable protein source, or a break from poultry. If you’re tracking meals and training, Fitnit can help by estimating macros from meal photos and counting reps during workouts, which makes it easier to keep your protein intake and training consistent without guesswork.

Tips

• Choose skinless chicken breast when you want the leanest, lowest-mercury option.
• Pick canned light tuna more often than albacore if you eat tuna regularly.
• Avoid turning either food into a calorie bomb with lots of mayo, butter, or heavy breading.
• Aim for variety: rotate chicken, tuna, eggs, beans, salmon, and Greek yogurt across the week.
• If you’re pregnant or feeding young kids, check current fish-consumption guidance before making tuna a staple.