Swiss Bircher muesli tradition (Dr. Maximilian Bircher-Benner, c.1900); modernised and viral via food blogs 2014 and TikTok 2020–2022
Overnight oats became a widespread food blog and social media trend from around 2014, popularised by the Bircher muesli tradition and health food culture, and reaching a new viral peak on TikTok in 2020–2022 with elaborate layered jar presentations. The concept is simple: rolled oats are mixed with liquid (milk or milk alternative) and left to soak overnight in the refrigerator. Enzymes in the oat begin to break down starches slightly, and the liquid is absorbed, producing a thick, creamy porridge texture without any cooking. The technique involves a critical ratio: 1 part oats to 1 part liquid produces thick overnight oats suitable for eating from a jar. Increasing the liquid to 1.5 parts produces a looser, pourable result. A tablespoon of chia seeds added to the mixture increases viscosity significantly through their hydrocolloid properties — chia seeds absorb up to 12 times their weight in liquid and create a pudding-like texture within the oats. The flavouring additions work best when added before soaking: vanilla extract, a teaspoon of honey or maple syrup, a spoonful of peanut or almond butter, or ground cinnamon. These flavours meld into the oat matrix during the overnight soak more effectively than when added in the morning. Fresh fruit and textural toppings — granola, nuts, seeds — should always be added at the moment of eating to preserve their texture. A small addition (1–2 tablespoons) of plain yoghurt or kefir to the soak liquid introduces lactic acid bacteria that partially ferment the oats overnight. This fermentation-adjacent process slightly reduces phytic acid (an anti-nutrient in oats), improves mineral absorption, and adds a subtle tang. This is not full fermentation but a nutritionally meaningful difference from plain soaked oats.
Creamy oat sweetness, mild vanilla and honey, tangy yoghurt note, fresh fruit brightness
Use the 1:1 oat-to-liquid ratio as the baseline — adjust to preference but understand the texture implication Add chia seeds for a thicker, pudding-like consistency — they hydrate overnight perfectly Add flavourings before soaking — they integrate into the oat matrix more effectively overnight Add textural toppings (granola, nuts, fresh fruit) only at the moment of serving A spoonful of yoghurt in the soak liquid provides mild fermentation that reduces phytic acid and adds tang
For a chocolate version, add 1 tablespoon of cocoa powder and a tablespoon of maple syrup to the soak — it tastes like chocolate mousse in the morning For a savoury overnight oat (less common but worthwhile), use broth as the liquid and top with a poached egg and sriracha A sprinkle of flaky salt on the finished bowl, even when sweet, elevates all the other flavours significantly For travel or commute, use a wide-mouth 500ml mason jar — the seal is perfect for overnight in the refrigerator and direct eating Steel-cut overnight oats require pre-cooking or a 2-day soak; rolled oats are the optimal format for the overnight method
Using instant oats — they over-absorb and turn into a gluey, unpleasant porridge Adding granola or crunchy toppings before refrigerating — they soften and lose all textural value overnight Using the wrong liquid-to-oat ratio — too much liquid produces a watery, unappetising result Not covering tightly — the surface of the oats oxidises and discolours overnight Forgetting to stir well before refrigerating — unevenly distributed chia seeds clump into dense pockets