Legumes are one of the most frustrating foods to weigh up on keto, because they are genuinely good for you and yet undeniably carby. Lentils, chickpeas, kidney beans, black beans and the rest are packed with protein, fibre and nutrients, the sort of food every other diet tells you to eat more of. So the honest answer to whether they are keto is a proper “it depends”, and the detail is worth understanding rather than just writing them off.

The carb reality

Start with the numbers, because they decide everything. Cooked lentils come in at roughly 20g of total carbohydrate per 100g, kidney and black beans are similar, and chickpeas are a bit higher at around 27g. A normal serving is rarely just 100g; a bowl of dhal or a scoop of chickpea curry can easily be two or three times that. Set against a strict keto budget of around 20 to 25g of carbs for the whole day, a single proper portion of any of them can use it all up in one go. That is why legumes get the red light on most keto lists.

Net carbs change the picture

There is a saving grace, and it is fibre. Legumes are full of it, and fibre is carbohydrate your body does not absorb or turn into glucose, so most keto eaters subtract it and count net carbs instead of total. Do that with lentils and the 20g total drops to roughly 12g net per 100g, because around 8g is fibre. Suddenly a small portion looks far more manageable: 60g of cooked lentils is only about 7g net, a fraction of a relaxed low-carb day rather than a catastrophe. The number that scares you is the total; the number that matters in practice is usually the net.

They are a good carb to spend on

If you are going to spend some of your carb allowance, legumes are one of the smarter places to spend it. They are low on the glycaemic index, which means they release their energy slowly and do not spike blood sugar the way an equal amount of white rice or bread would. They bring a hefty dose of protein and fibre along for the ride, both of which help you feel full and support your gut. So a spoonful of lentils is a very different thing, nutritionally, from a spoonful of mashed potato, even if the carb count looks similar on paper.

So where do they fit?

It comes down to which version of low-carb you are doing. On strict keto, holding under about 20g net carbs a day, legumes are essentially out as a regular food; there is rarely room for more than a token amount without blowing the day. On a more relaxed low-carb approach, say 50 to 100g of net carbs a day, a modest portion of lentils or beans fits comfortably and brings real nutritional benefit. Neither answer is wrong, they are just different diets with different room to move.

The practical trick, if you want them, is to treat legumes as an accent rather than the base. A spoonful of lentils stirred through a big plate of vegetables and meat is a world away from a bowl of lentil stew that is mostly lentils. Use them to add texture, protein and interest in small amounts, not as the main event, and they can earn their place even on a fairly tight day.

The genuinely low-carb legumes

Not all legumes are equal, and a few are low enough in carbohydrate to be properly keto-friendly. Lupini beans are the standout: very high in protein and fibre and very low in net carbs, which is why they turn up as a keto snack. Edamame, which is immature soybeans, comes in at only around 4 to 5g net carbs per 100g, low enough to enjoy as a starter or snack. Black soybeans are similarly low and are often used as a keto substitute for ordinary black beans. Peanuts, which are botanically a legume, are also low-carb. So if you love the legume family, these are the members you can lean on freely, while saving lentils, chickpeas and the starchier beans for smaller, considered portions.

A note on the bigger picture

It is worth remembering that fibre and the nutrients legumes provide are genuinely good for you, and that a very meat-and-cheese version of keto misses out on a lot of that. As the piece on cooking keto without special recipes argues, the healthiest way to do this is heavy on plants. A small amount of legume, fitted sensibly into your day, can be part of that rather than something to feel guilty about, particularly on the relaxed end of low-carb.

The bottom line

Are lentils and legumes keto? On strict keto, not really, a normal portion uses your whole day’s carbs, so they become an occasional token at most. But count net rather than total carbs and the fibre brings them down to roughly 12g per 100g for lentils, which means a small scoop fits fine on a relaxed low-carb day, and they are one of the better carbs to spend your budget on. If you want legumes you can eat freely, reach for lupini beans, edamame or black soybeans. The rest are a “a little, sometimes, counted carefully” food, which, for something this nourishing, is no bad place to land.

This is general information about the ketogenic diet, not medical advice. Keto does not suit everyone; if you are pregnant, on medication, or managing a condition such as diabetes, speak to a doctor or dietitian first.