Legumes

Most legumes are lower in the amino acid methionine, so they are not considered complete proteins on their own. Soybeans and products like tofu and tempeh are exceptions and contain all nine essential amino acids in adequate amounts. Pairing legumes with grains such as rice, wheat, or corn over the course of the day provides a complementary amino acid profile.

Legumes contain oligosaccharides like raffinose and stachyose that human digestive enzymes cannot break down, so gut bacteria ferment them in the colon, producing gas. Soaking dried beans, discarding the soaking water, and cooking thoroughly reduces these compounds. Rinsing canned legumes and gradually increasing intake also helps the gut microbiome adapt over time.

Lentils typically have a glycemic index between 25 and 35, and chickpeas fall in the 28 to 36 range, both classified as low GI. This is due to their high content of soluble fiber, resistant starch, and protein, which slow carbohydrate absorption. They tend to produce a more gradual blood glucose response compared with refined grains or potatoes.

Most legumes are too high in carbohydrates for a strict ketogenic diet, with cooked beans and lentils providing 20-40 grams of net carbs per cup. Black soybeans and peanuts are lower-carb exceptions sometimes included in keto plans. On more flexible low-carb approaches, small portions of lentils or chickpeas may fit within a daily carb allowance.