Calories in Flank Steaks: Nutrition Facts & Serving Sizes
Per 1 oz (28g)
Per 100g
Source: USDA FoodData Central, SR Legacy, March 2026.
Flank steak is a lean, flat cut of beef from the abdominal muscles of the cow. It has a bold, beefy flavor and a coarser grain than premium cuts. A 4oz serving (113g) contains 187 calories, 24g of protein, and 9.4g of fat with zero carbs. Per 100g, flank steak delivers 165 calories and 21.2g of protein, making it one of the better protein-to-calorie ratios among beef cuts. It is leaner than ribeye (187 cal/100g) and significantly leaner than ground beef (332 cal/100g). Flank steak is high in zinc (3.8mg per 100g), selenium (23.3mcg per 100g), and niacin (6.8mg per 100g), supporting testosterone production, thyroid function, and energy metabolism. It is a staple in high-protein meal prep and works well in fajitas, stir-fries, and sliced over salads.
Nutrition Highlights
Calories by Serving Size
| Serving | Cal | Protein | Carbs | Fat | Fiber |
|---|---|---|---|---|---|
| 4 oz (113g) | 186.5 | 24g | 0g | 9.4g | 0g |
| 1 steak (202g) | 333.3 | 42.8g | 0g | 16.8g | 0g |
| 1 oz (28g) | 46.9 | 6g | 0g | 2.4g | 0g |
| 100g | 165 | 21.2g | 0g | 8.3g | 0g |
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Full Nutrition Facts (per 100g)
| Nutrient | Amount | % Daily Value |
|---|---|---|
| Calories | 165 | 8% |
| Protein | 21.2g | 42% |
| Total Fat | 8.3g | 11% |
| Saturated Fat | 3.4g | 17% |
| Total Carbohydrates | 0g | |
| Dietary Fiber | 0g | |
| Sugars | 0g | |
| Sodium | 54mg | 2% |
| Cholesterol | 68mg | 23% |
Vitamins & Minerals (per 100g)
| Nutrient | Amount | % Daily Value |
|---|---|---|
| Saturated Fat | 3.4g | 1% |
| Cholesterol | 68mg | 23% |
| Calcium | 27mg | 2% |
| Iron | 1.6mg | 9% |
| Potassium | 330mg | 7% |
| Vitamin D | 0.1mcg | 1% |
| Vitamin B6 | 0.6mg | 35% |
| Vitamin B12 | 1.2mcg | 50% |
| Magnesium | 22mg | 5% |
| Phosphorus | 193mg | 15% |
| Zinc | 3.8mg | 35% |
| Selenium | 23.3mcg | 42% |
| Folate | 12mcg | 3% |
| Thiamin (B1) | 0.1mg | 8% |
| Riboflavin (B2) | 0.1mg | 8% |
| Niacin (B3) | 6.8mg | 43% |
% Daily Values based on a 2,000 calorie diet (FDA reference).
Health Benefits of Flank Steaks
Flank steak provides 21.2g of complete protein per 100g, delivering all essential amino acids needed for muscle protein synthesis. The high leucine content in beef protein makes it particularly effective at stimulating muscle growth when consumed after resistance training. A full steak at 202g delivers 42.8g of protein in one meal.
Zinc content at 3.8mg per 100g is significant. Zinc is directly involved in testosterone biosynthesis, and research shows that even moderate zinc deficiency can reduce testosterone levels. A 4oz serving of flank steak provides about 4.3mg of zinc, contributing meaningfully toward the 8 to 11mg daily recommended intake.
Selenium at 23.3mcg per 100g supports thyroid function and acts as a cofactor for glutathione peroxidase, one of the body's primary antioxidant enzymes. This helps reduce oxidative stress from training.
Niacin (vitamin B3) at 6.8mg per 100g plays a direct role in energy metabolism by supporting NAD and NADP production, which are essential for converting food into usable energy during exercise.
With zero carbohydrates, flank steak provides clean protein and fat energy without spiking blood glucose. The moderate fat content of 8.3g per 100g (including 3.4g saturated and 3.4g monounsaturated) supports hormone production without excessive saturated fat intake.
Dietary Considerations
Flank steak is naturally gluten-free, dairy-free, and zero-carb, making it suitable for keto, carnivore, paleo, and Whole30 diets. It is not appropriate for vegan or vegetarian eating patterns. For weight loss, flank steak is one of the better beef options given its lean profile at 165 calories per 100g compared to fattier cuts. The high protein content keeps you full and preserves muscle mass during a calorie deficit. Sodium is low at 54mg per 100g before seasoning. Cholesterol is 68mg per 100g, which is typical for lean beef. Flank steak is best prepared quickly over high heat and sliced thin against the grain to maximize tenderness. No major allergen concerns beyond beef itself.
Daily Intake (100g)
100g of flank steak provides 8% of a 2,000-calorie diet.
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Frequently Asked Questions
How many calories in flank steak?
A 4oz serving of flank steak (113g) contains about 187 calories. A full steak (202g) has around 333 calories. Per 100g, flank steak contains 165 calories.
Is flank steak good for weight loss?
Flank steak is one of the better beef cuts for weight loss. At 165 calories and 21.2g of protein per 100g, it offers a strong protein-to-calorie ratio that supports satiety and muscle preservation during a calorie deficit. Keep portion sizes to 4-6oz and avoid high-calorie marinades.
How much protein in flank steak?
A 4oz serving (113g) of flank steak contains 24g of protein. A full steak (202g) delivers 42.8g of protein. Per 100g, flank steak has 21.2g of complete protein.
Is flank steak keto-friendly?
Yes. Flank steak has zero carbohydrates, making it fully compatible with keto and low-carb diets. Its lean profile also makes it practical for keto dieters who want protein without excessive fat calories.
How does flank steak compare to sirloin?
Flank steak (165 cal/100g, 21.2g protein) and sirloin (182 cal/100g) are both lean beef options. Flank is slightly leaner and often less expensive than sirloin. Both are good choices for high-protein, muscle-building diets.
What is the best way to cook flank steak for meal prep?
Flank steak is best cooked quickly over high heat to medium-rare or medium, then sliced thin against the grain. Overcooking makes it tough. For meal prep, marinate it to add flavor without significant calories, then slice and store for use in bowls, wraps, and salads throughout the week.
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