Calories in Oysters: Nutrition Facts & Serving Sizes
Per 3 oz (85g)
Per 100g
Source: USDA FoodData Central, SR Legacy, March 2026.
Oysters deliver 141 calories per 100g alongside an impressive 22.8g of protein, making them one of the most protein-dense shellfish options available. A standard 3-oz serving (85g) provides about 120 calories and 19.4g of protein with zero carbs. The standout micronutrient is zinc at 6mg per 100g, a mineral critical for testosterone production, immune function, and protein synthesis. Vitamin B12 hits 6.8mcg per 100g, far exceeding the daily requirement of 2.4mcg in a single serving. Selenium comes in at 29.8mcg, supporting thyroid health and antioxidant defense. Iron at 5.5mg and phosphorus at 217mg per 100g round out a micronutrient profile that outperforms most protein sources. With zero carbs and moderate fat (4.9g), oysters fit cleanly into high-protein, low-carb, and keto diets.
Nutrition Highlights
Calories by Serving Size
| Serving | Cal | Protein | Carbs | Fat | Fiber |
|---|---|---|---|---|---|
| 3 oz (85g) | 119.9 | 19.4g | 0g | 4.2g | 0g |
| 1 steak (300g) | 423 | 68.4g | 0g | 14.7g | 0g |
| 100g | 141 | 22.8g | 0g | 4.9g | 0g |
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Full Nutrition Facts (per 100g)
| Nutrient | Amount | % Daily Value |
|---|---|---|
| Calories | 141 | 7% |
| Protein | 22.8g | 46% |
| Total Fat | 4.9g | 6% |
| Saturated Fat | 1.2g | 6% |
| Total Carbohydrates | 0g | |
| Dietary Fiber | 0g | |
| Sugars | 0g | |
| Sodium | 150mg | 7% |
| Cholesterol | 81mg | 27% |
Vitamins & Minerals (per 100g)
| Nutrient | Amount | % Daily Value |
|---|---|---|
| Saturated Fat | 1.2g | 0% |
| Cholesterol | 81mg | 27% |
| Calcium | 4mg | 0% |
| Iron | 5.5mg | 31% |
| Potassium | 250mg | 5% |
| Vitamin B6 | 0.6mg | 35% |
| Vitamin B12 | 6.8mcg | 283% |
| Magnesium | 30mg | 7% |
| Phosphorus | 217mg | 17% |
| Zinc | 6mg | 55% |
| Selenium | 29.8mcg | 54% |
| Folate | 13mcg | 3% |
| Thiamin (B1) | 0.3mg | 25% |
| Riboflavin (B2) | 0.5mg | 38% |
| Niacin (B3) | 7.5mg | 47% |
% Daily Values based on a 2,000 calorie diet (FDA reference).
Health Benefits of Oysters
Oysters are among the most micronutrient-dense protein sources in existence. Zinc at 6mg per 100g is particularly significant for active people. Zinc is required for hormone production, immune defense, wound healing, and protein synthesis. Most people get adequate zinc from red meat, but oysters are one of the highest dietary sources available.
Vitamin B12 at 6.8mcg per 100g is exceptional. B12 supports the formation of red blood cells, neurological function, and DNA synthesis. A single 3-oz serving of oysters provides more B12 than most people need in a day, making oysters a highly efficient way to stay topped up on this often-deficient nutrient.
Selenium (29.8mcg per 100g) is a co-factor for antioxidant enzymes like glutathione peroxidase, which neutralize free radicals generated during intense training. Adequate selenium is also tied to healthy thyroid hormone production, which influences metabolism and energy levels.
Iron at 5.5mg per 100g supports oxygen-carrying hemoglobin in red blood cells, directly impacting endurance performance and recovery. The combination of high protein, zero carbs, and outstanding micronutrient density makes oysters a genuinely elite food for performance-focused nutrition.
Dietary Considerations
Oysters are naturally gluten-free, dairy-free, and keto-friendly with zero carbs per serving. They are not vegan or vegetarian. The 81mg of cholesterol per 100g is a consideration for individuals managing cholesterol levels, though dietary cholesterol has a smaller impact on blood cholesterol than saturated fat for most people. Sodium at 150mg per 100g is moderate. Oysters are a shellfish and a common allergen, so those with shellfish allergies must avoid them entirely. For anyone in a cutting phase, the combination of very high protein, zero carbs, and moderate fat makes oysters an outstanding dietary choice.
Daily Intake (100g)
100g of oyster provides 7% of a 2,000-calorie diet.
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Frequently Asked Questions
How many calories in oysters?
Oysters have 141 calories per 100g. A standard 3-oz serving (85g) contains about 120 calories. A larger 300g serving delivers 423 calories.
Are oysters good for weight loss?
Yes. Oysters are high in protein (22.8g per 100g), have zero carbs, and deliver roughly 120 calories per 3-oz serving. The high protein content supports satiety and muscle retention during a calorie deficit, making them excellent for cutting.
How much protein is in oysters?
Oysters contain 22.8g of protein per 100g. A 3-oz serving (85g) provides 19.4g of protein, and a larger 300g serving delivers 68.4g of protein.
Are oysters high in zinc?
Yes. Oysters contain 6mg of zinc per 100g. Zinc is critical for testosterone production, immune function, and muscle protein synthesis. Oysters are one of the best dietary sources of zinc available.
Are oysters keto-friendly?
Yes. Oysters contain zero carbs per serving, making them fully compatible with strict ketogenic diets. The protein and fat content support satiety on a keto approach without any carb cost.
How much vitamin B12 is in oysters?
Oysters contain 6.8mcg of vitamin B12 per 100g. The daily recommended intake for adults is 2.4mcg, meaning a single 3-oz serving provides well over a full day's requirement.
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