Lentils are a perfect example of why nutrition numbers need a preparation state. One hundred grams dry and 100 g cooked do not represent the same amount of original lentil solids. Cooking adds water, so nutrients become less concentrated per 100 g.
Cooked lentils: what reaches the plate
| Per 3.5 oz (100 g) cooked | Approximate amount |
|---|---|
| Calories | 116 kcal |
| Protein | 9.0 g |
| Carbohydrate | 20.1 g |
| Fiber | 7.9 g |
| Fat | 0.4 g |
| Iron | 3.3 mg |
| Folate | ~180 mcg |
One cooked cup is about 198 g, which works out to roughly 230 calories, 17.8 g protein, 15.6 g fiber, and about 6.6 mg iron.
The serving matters more than a single per-100-g number. A full cup nearly doubles the table values and turns a moderate protein concentration into a meaningful contribution to a meal.
Dry vs. cooked: ~24–25 g vs. ~9 g protein per 100 g
Dry lentils contain about 24–25 g protein and roughly 350 calories per 100 g, compared with 9 g protein and 116 calories when cooked. Cooking did not destroy two-thirds of the protein; water greatly increased the weight.
That is why comparing 100 g dry with 100 g cooked compares different amounts of dry matter. Use the value that matches the food as you actually eat it.
The same principle explains why a dry-bag label can look much more concentrated than canned lentils. Water changes nutrient density per 100 g without turning lentils into a nutritionally different food.
Protein matters, but fiber changes the comparison
One cooked cup provides almost 18 g of protein. The same 198 g of cooked chicken breast would provide more than 60 g protein, but the lentils also provide about 15.6 g fiber while chicken provides 0 g.
They are different nutrient profiles, not gram-for-gram substitutes.
In a meat-free meal, lentils can also be combined with bread, grains, nuts, or another food to raise total protein without needing to match chicken’s concentration by themselves.
Lentils are rich in iron, but it is nonheme iron
At roughly 3.3 mg per 100 g cooked, lentils contribute a meaningful amount of iron. It is nonheme iron, which is absorbed more variably than heme iron from meat.
Eating lentils with vitamin C-rich foods—such as bell pepper, tomatoes, citrus, or kiwi—can improve nonheme iron absorption.
That is why the milligrams on a nutrition table do not tell the entire absorption story. Meal composition and a person’s iron status influence how much nonheme iron is ultimately absorbed.
Fiber is one of their biggest strengths
A cooked cup provides about 15–16 g of fiber. That fiber adds bulk to the meal and reaches the colon, where some of it is fermented by gut microbes.
For someone who is not used to a high-fiber diet, increasing legumes gradually may be more comfortable than jumping from small portions to a full cup or more overnight.
Canned lentils live in the “cooked” world
Canned lentils are already hydrated and cooked, so their protein and calorie values per 100 g are much closer to boiled lentils than dry lentils. Sodium is the bigger variable; check the drained weight and Nutrition Facts label.
Draining makes the serving easier to compare, and rinsing salted products can reduce some sodium without removing the protein and fiber that remain in the lentils.
You do not have to pair lentils with rice at the same meal
Lentils contain all essential amino acids, but their amino-acid pattern differs from egg, meat, and dairy proteins. That quality distinction does not change the roughly 9 g protein per 3.5 oz (100 g) in cooked lentils; a varied diet supplies other amino acids across the day, so a legume and grain do not have to be eaten in the same bowl.
Rice and lentils remain a useful and traditional combination, but they can be paired for flavor, energy, and extra protein rather than because lentils completely lack an essential amino acid.
Bottom line
For a real meal, cooked values are the useful reference: about 116 calories, 9 g protein, and 7.9 g fiber per 100 g. A cooked cup provides nearly 18 g protein and 16 g fiber, plus iron and folate.
Sources
- USDA FoodData Central — Composition of dry and cooked lentils; values per 100 g.
- NIH Office of Dietary Supplements — Iron — Heme/nonheme iron and factors affecting absorption.