Lentils have the second-highest ratio of protein per calorie of any legume, after soybeans. Lentils contain the carotenoids, lutein and zeaxanthin, and polyunsaturated fatty acids.
100 g of raw lentils (variety unspecified) provide 353 calories; the same weight of cooked lentils provides 116 calories.
Raw lentils are 8% water, 63% carbohydrates including 11% dietary fiber, 25% protein, and 1% fat (table).
Lentils are a rich source (20% or more of the Daily Value, DV) of numerous essential nutrients, including folate (120% DV), thiamin (76% DV), pantothenic acid (43% DV), vitamin B6 (42% DV), phosphorus(40% DV), iron (50% DV), and zinc (35%), among others (table).
When lentils are cooked by boiling, protein content declines to 9% of total composition, and B vitamins and minerals decrease due to the overall water content increasing (protein itself is not lost).
The low levels of readily digestible starch (5%) and high levels of slowly digested starch make lentils of potential value to people with diabetes. The remaining 65% of the starch is a resistant starch classified as RS1. A minimum of 10% in starch from lentils escapes digestion and absorption in the small intestine(therefore called "resistant starch"). Additional resistant starch is synthesized from gelatinized starch, during cooling, after the lentils were cooked.
Lentils also have antinutrient factors, such as trypsin inhibitors and a relatively high phytate content. Trypsin is an enzyme involved in digestion, and phytates reduce the bioavailability of dietary minerals. The phytates can be reduced by prolonged soaking and fermentation or sprouting.
Great blog article from thekitchn.com
5 Mistakes to Avoid while cooking LENTILS