Peanut Butter, Banana & Oat Smoothie

Why it works

This combination is everywhere because it works, and it is worth saying why rather than treating it as a default. Oats carry beta-glucan, the soluble fiber that forms a gel in the stomach and slows how fast everything leaves it, which is the mechanism behind oats feeling more filling per calorie than most breakfasts. Greek yogurt roughly doubles the protein of the same drink made with milk. Peanut butter adds fat, which slows gastric emptying further, and a slightly underripe banana carries more resistant starch, a form that escapes digestion in the small intestine and gets fermented by gut bacteria instead. Four ordinary ingredients, three separate mechanisms all pointing at the same thing: staying full.

Ingredients

• 150 g plain Greek yogurt
• 200 ml milk or unsweetened soy milk
• 1 barely ripe banana (about 110 g)
• 40 g (1/2 cup) old-fashioned rolled oats
• 1.5 tbsp (24 g) natural peanut butter
• 1/2 tsp ground cinnamon

Method

1. Pour the liquid into the blender first, then add the soft ingredients, then anything frozen or hard on top. Blending in that order keeps the blades in liquid instead of spinning against a frozen block.
2. Use a banana with no brown spots. A green-tipped one carries noticeably more resistant starch and less sugar, and the difference in sweetness is smaller than you would expect.
3. Blend on low until it breaks up, then on high for 45 to 60 seconds, until no flecks remain and the texture is even.
4. Taste and adjust: a splash more liquid if it is too thick to pour, a squeeze of citrus if it tastes flat, a few more ice cubes if you want it colder.
5. Drink it soon after blending. The texture separates within about ten minutes, and the colour dulls as the cut surfaces oxidise.