White Bean, Kale and Lemon Soup
Tinned beans, a bag of kale, and a lemon: twenty minutes from cupboard to bowl, thickened by crushing some of the beans rather than with anything else.
Why it works
Two things make a soup fill you up instead of just passing through. The first is energy density: a high-water, low-calorie bowl eaten before or as a meal reduces total intake at that meal, which is Barbara Rolls' volumetrics finding and one of the more reliably repeated results in appetite research. The second is what's dissolved in the water, and here that's the soluble fiber and resistant starch from cannellini beans, which slow gastric emptying and feed the gut bacteria that produce short-chain fatty acids and trigger the satiety hormones GLP-1 and PYY. Crushing a ladle of the beans against the pan is the thickening trick: it releases starch into the broth so the soup gets body without cream or flour anywhere near it.
The volumetrics work on low-energy-density soups reducing subsequent intake is well replicated. Legume fiber and satiety hormone response has good trial support. Neither says anything about weight over a year, which depends on far more than one lunch.
Ingredients
- 2 tbsp extra-virgin olive oil
- 1 onion, chopped
- 2 celery sticks, sliced
- 3 garlic cloves, sliced
- 1 tsp fennel seeds
- A pinch chilli flakes
- 2 x 400 g tins cannellini beans, drained and rinsed
- 1 litre low-sodium vegetable stock
- 150 g kale, stems removed and shredded
- 1 lemon, zested and juiced
- 30 g parmesan or pecorino, grated, to serve
Method
- Warm the oil and cook the onion and celery for eight minutes until soft, then add the garlic, fennel seeds and chilli for a minute.
- Add the beans and stock and simmer for ten minutes.
- Crush about a third of the beans against the side of the pan with a wooden spoon and stir them back in. That is what thickens it.
- Add the kale and cook for three minutes, until it is tender but still dark green.
- Off the heat, add the lemon zest and juice. Taste: bean soup takes more salt and more acid than seems reasonable.
- Finish each bowl with grated cheese and a thread of olive oil.
