Pig skin is predominantly collagen, not fat. The skin itself, specifically the dermis (the thick main layer), is a dense connective tissue where collagen makes up roughly 80% of the dry protein matrix. Fat does exist beneath the skin in a separate layer called subcutaneous adipose tissue, but that layer is anatomically distinct from the skin itself. The confusion usually comes from how pig skin feels when raw or how it’s prepared in cooking, where added fat changes the final product significantly.
What Pig Skin Is Made Of
Pig skin has three layers: a thin outer epidermis, a thick dermis, and a subcutaneous fat layer underneath. The dermis is the bulk of what you’d recognize as “the skin,” and it’s packed with collagen fibers. Analysis of porcine dermis shows that Type I collagen accounts for about 55% and Type III collagen about 27% of the tissue matrix. Together, those two collagen types make up over 81% of the dermal structure, with the remainder being elastin, water, and small amounts of other proteins.
Type I collagen provides tensile strength, the resistance to tearing and stretching. Type III collagen is softer and more flexible, found alongside blood vessels and in younger tissue. Pig skin contains both in a ratio that’s remarkably similar to human skin, which is one reason porcine collagen is so widely used in medical products and supplements.
Where the Fat Actually Sits
The fat people associate with pig skin comes from the subcutaneous layer, which sits below the dermis. This is technically not skin but rather the fatty tissue attached to it. Adipose tissue is 60 to 80% lipid by weight, with the rest being water and a small fraction of protein. When you buy pork skin with a thick white layer on one side, that white layer is subcutaneous fat, not the skin itself.
Butchers and processors can trim this fat layer off, leaving behind the translucent, tough, collagen-rich dermis. How much fat remains depends entirely on how the skin is prepared. A well-trimmed piece of pig skin is almost pure collagen and water. A piece with the fat cap still attached can look and feel greasy, giving the false impression that the skin itself is fatty.
How Cooking Changes the Ratio
Raw pig skin that’s been properly trimmed is lean, dense, and chewy. Cooking transforms it in different ways depending on the method.
When pig skin is simmered in water, the collagen breaks down into gelatin. This is exactly what happens when you make bone broth or stock: the collagen dissolves, and the liquid gels when cooled. Pig skin produces a high gelatin yield compared to other animals, about 12.5% by weight, higher than both chicken skin (8.2%) and bovine skin (12.0%).
Deep-frying is a different story. Pork rinds (chicharrones) are made by first rendering out moisture and any residual fat, then frying the dried skin until it puffs. The frying process adds oil. Traditional deep-fried pork rinds end up with about 36 grams of fat per 100 grams of dry product. That fat is almost entirely absorbed from the frying oil, not from the skin itself. Microwave-assisted frying drops that to around 24 grams, and vacuum frying brings it down to about 17 grams per 100 grams.
So when you eat fried pork rinds, you’re eating collagen protein that has absorbed a significant amount of cooking oil. The skin contributed the protein; the fryer contributed the fat.
Pig Skin as a Collagen Source
Porcine skin is one of the most common raw materials for commercial collagen and gelatin products. This includes gelatin capsules, gummy candies, collagen supplements, and medical-grade wound dressings. The reason is straightforward: pig skin is abundant, has a very high collagen density, and its collagen closely resembles the human version in structure.
When pig skin collagen is broken down into smaller peptides for supplements, the body absorbs it efficiently. In a randomized crossover study comparing collagen from porcine, bovine, and fish sources, porcine collagen produced 20% higher blood levels of total hydroxyproline (a key collagen building block) compared to fish collagen. Porcine collagen also delivered 1.4 times more of a specific collagen peptide called Pro-Hyp compared to bovine sources, and 1.8 times more of the tripeptide Gly-Pro-Hyp. These differences suggest that pig-derived collagen is absorbed at least as well as, and in some measures better than, other common sources.
The Short Answer for Cooking and Nutrition
If you’re eating pig skin for protein or using it to make stock, you’re getting collagen. A serving of boiled or braised pig skin is high in protein and relatively low in fat, assuming the subcutaneous layer has been trimmed. If you’re eating fried pork rinds, the protein still comes from collagen, but the fat content jumps because of the frying process. The skin itself never had much fat to begin with.
For anyone buying pig skin at a butcher or grocery store, the thickness and texture of what you’re holding is almost entirely collagen. The squishy, soft white layer on the underside is fat and can be scraped or trimmed away. Once that’s gone, what remains is one of the richest whole-food sources of collagen available.