Why Flank Steak Loses Weight When Cooked
Cooking meat is a scientific process where heat causes significant physical changes. The primary reasons a flank steak loses weight are water evaporation, fat rendering, and protein contraction.
- Water Evaporation: Meat, including lean flank steak, is composed of a large percentage of water. When heat is applied, this water turns to steam and evaporates, naturally reducing the overall weight. The cooking temperature directly impacts the rate and amount of moisture lost; higher heat accelerates evaporation.
- Fat Rendering: While flank steak is a lean cut, it still contains some intramuscular fat. When heated, this fat melts and drips away, further decreasing the total weight. The extent of this loss is less significant than with fattier cuts like ribeye, but still contributes to the overall reduction.
- Protein Contraction: The muscle fibers within the steak contract and shorten when exposed to heat, squeezing out moisture and juices. This process is largely responsible for the steak's shrinkage in both size and weight. Overcooking intensifies this contraction, resulting in a tougher, drier steak with a higher percentage of weight loss.
Factors Influencing Flank Steak Shrinkage
Several variables determine the exact percentage of weight your flank steak will lose. Being mindful of these can help you achieve a more consistent and predictable outcome.
- Cooking Temperature: Higher temperatures cause more rapid and aggressive protein contraction, which expels more moisture. Cooking over medium-high heat for a shorter duration, as is common with grilling or pan-searing flank steak, helps retain moisture compared to slow cooking at very high heat.
- Degree of Doneness: Flank steak is best cooked to medium-rare or medium to maintain tenderness. A well-done steak, cooked to a higher internal temperature, will inevitably lose more moisture and weigh significantly less than a rare or medium-rare steak.
- Cooking Method: The technique used can greatly influence moisture retention. Moist-heat methods, like braising, can lead to less net weight loss as the meat cooks in its own juices, while dry-heat methods like grilling or broiling result in higher weight loss.
- Resting Time: Resting the steak after cooking is a critical step that allows the muscle fibers to relax and reabsorb some of the juices. Cutting into the steak too early will cause the remaining juices to escape onto the cutting board, leading to greater weight loss.
Comparing Cooking Methods and Weight Loss
| Cooking Method | Typical Flank Steak Result | Approximate Weight Loss | Notes |
|---|---|---|---|
| Grilling | Smoky flavor, great crust, medium-rare finish | 25-30% | High heat for a short time can cause quick moisture loss if not managed properly. |
| Pan-Searing | Flavorful crust, juicy interior | 20-25% | Using a cast-iron skillet creates a great crust while controlling heat for a perfect medium-rare. |
| Sous Vide | Exceptionally tender and juicy | 10-15% | The vacuum-sealed bag prevents moisture from escaping, resulting in minimal weight loss. |
| Braising | Fork-tender, but loses texture | Can be variable | Cooked in liquid, so weight loss is less about moisture escaping and more about texture breakdown. |
How to Minimize Flank Steak Weight Loss
To ensure your flank steak remains as juicy and heavy as possible, follow these practical tips:
- Marinate with an Acid: Marinating flank steak with acidic ingredients like vinegar or lemon juice helps break down tough muscle fibers, which reduces the amount of moisture they expel when cooked. Aim for at least 4 hours of marinating time.
- Pat the Steak Dry: Before cooking, patting the surface of the steak with paper towels removes excess moisture. This is crucial for achieving a good sear, as the moisture would otherwise create steam and cause the steak to cook unevenly.
- Cook Hot and Fast to Medium-Rare: High-heat, short-duration cooking is ideal for flank steak. This sears the exterior quickly while keeping the interior juicy. Using a meat thermometer is the most reliable way to prevent overcooking and excessive weight loss.
- Rest the Steak: After removing the steak from the heat, let it rest for 5 to 10 minutes. This allows the muscle fibers to relax and reabsorb juices, ensuring a more tender and flavorful result. Cutting it too soon will cause the juices to run out.
- Slice Against the Grain: Flank steak has prominent muscle fibers, or "the grain." Slicing the cooked steak thinly against the grain shortens these fibers, making it much more tender and easier to chew.
Conclusion
While some weight loss is unavoidable when cooking flank steak, it is a predictable process that you can manage. Expect a standard 25% reduction in raw weight, with variations based on your chosen cooking method, temperature, and final doneness. By marinating, searing properly, and resting your steak, you can minimize shrinkage and maximize the flavor and tenderness of this popular, lean cut. Understanding the science behind meat shrinkage ensures that your culinary efforts are consistently rewarded with a perfect, juicy steak every time.
How to calculate cooked portion size
When planning a meal, remember that a standard 1.5-2 lb raw flank steak, when cooked, will likely yield around 1.1 to 1.5 lbs of cooked meat, potentially feeding 4 to 6 people. Adjust raw meat purchases accordingly to meet your serving needs.
How much does a steak shrink after cooking?
Steaks generally shrink by around 25% of their raw weight after cooking, with leaner cuts like flank steak potentially on the lower end of this range. The weight loss is a combination of water evaporating and fat rendering out.
Does adding marinade reduce flank steak shrinkage?
Yes, marinating with an acidic base can help. The acid breaks down some of the muscle fibers, which can help them retain moisture more effectively during cooking, thus reducing shrinkage.
What happens if you don't let flank steak rest?
If you cut into the flank steak immediately after cooking, the internal pressure will cause the remaining juices to flow out onto your cutting board. This results in a drier, less flavorful steak and a greater net weight loss.
Is flank steak healthier than a ribeye due to weight loss?
Since flank steak is a leaner cut with less fat to begin with, it will typically end up with a lower fat and calorie count per cooked ounce compared to a fattier cut like ribeye. However, the weight loss percentages themselves are comparable.
How does the cooking temperature affect weight loss?
Cooking at a higher temperature, for a shorter duration, can cause less moisture loss than cooking slowly at high heat for a longer time. However, overcooking at any temperature will lead to excessive moisture loss and a tougher result.
Does scoring flank steak reduce weight loss?
Scoring the surface of a flank steak does not reduce weight loss directly, but it can aid in tenderness. It allows marinades to penetrate deeper and can help prevent the steak from curling during cooking, ensuring a more even cook.
How can I be sure to get a tender flank steak?
To guarantee a tender result, focus on three key steps: marinate the steak, cook it quickly over high heat to medium-rare, and, most importantly, slice it thinly against the grain after letting it rest.
