Cook once, eat all week: the building-block method, correct portions and the storage rules that actually protect you — two to three days, not four.
The short answer: cook one block of two to three hours a week, portion it out immediately, cool it fast — and eat those portions within two to three days [1]. Anything meant to last longer goes into the freezer on cooking day. Not on day three. On cooking day.
Yes, "three to four days" appears in almost every meal-prep article. But the recommendation from Germany's Federal Institute for Risk Assessment is two to three days [1], and that is the figure to plan around. The difference between those two numbers is exactly the buffer you already spent by leaving a lukewarm pot on the counter.
And the effort pays off measurably. In an analysis of US dietary data, households cooking dinner six to seven evenings a week consumed on average 9,054 instead of 9,627 kilojoules a day, 81 instead of 86 g of fat and 119 instead of 135 g of sugar [2] — roughly 140 kilocalories and half a chocolate bar of sugar less, every day, without going without. This is observational data, not proof of cause and effect. But the direction is unambiguous: people who cook eat differently.
Count how many meals you actually want to replace. Five lunches? Then you need five portions, not "a bit more rice".
Build each portion around your protein target: roughly 0.4 g of protein per kilogram of body weight per meal across at least four meals is the most practical route to a sensible daily intake [3]. At 80 kg that is 32 g per box — about 150 g of chicken breast, 200 g of quark, or a generous ladle of lentils.
Meal prep almost never fails at the cooking, it fails at the quantity: too little cooked means a delivery order on Thursday.
Do not cook five finished meals. Cook three building blocks you combine differently: one carbohydrate source (rice, potatoes, pasta), two protein sources (chicken and lentils, for example), two or three vegetables — plus two sauces or dressings that do the heavy lifting on flavour.
The reason is not efficiency, it is stamina: nobody willingly finishes the same curry five times. Store separately, combine only on the plate — then Thursday tastes different from Monday.
The order decides how long it takes. Start with whatever takes longest and runs unattended: oven on, vegetables and potatoes onto the tray. Rice or pasta on the hob meanwhile. The protein goes in the pan last.
Cook things one after another and you are busy for four hours. Cook in parallel and you are done in under two.
This is the part almost everyone gets wrong, and the only one where a mistake genuinely hurts.
The target: get cooked food below +7 °C within a few hours — for pre-cooked rice and pasta the guideline is around 120 minutes [1]. Portion large quantities into shallow containers rather than cooling a whole pot. A shallow layer cools many times faster than a full pot.
And the fridge itself has to play along: maximum +7 °C, better +5 °C [4]. Hence the thermometer — most household fridges run warmer than their owners believe.
Close the containers once the contents are hand-warm, then straight into the fridge. Date on the lid, no exceptions.
Then the rule this whole guide revolves around: two to three days in the fridge [1]. Whatever you will not eat in that window goes into the freezer on cooking day, not later. Fish, leaf salads and anything containing raw egg get planned for the first one to two days as a matter of principle.
Reheating comes down to a single number: at least +70 °C right through the core [5]. Thorough heating to +70 to +80 °C for at least two minutes kills the relevant bacteria [4].
This matters most with rice and pasta: both can carry Bacillus cereus, a spore-forming bacterium that loves lukewarm storage and whose toxin can no longer be fully neutralised by reheating [5]. So only reheat what has been kept consistently chilled.
In the microwave, stir once and run it another minute — microwaves heat unevenly, and the cold core in the middle is precisely the problem.
This guide explains and motivates, it does not replace medical or dietetic advice. The storage times given are general orientation values for healthy adults.
Stricter rules apply to pregnant women, small children, older people and anyone with a weakened immune system — there, every uncertainty belongs on the cautious side, and when in doubt with a doctor or an official consumer advice service.
When in doubt the rule is always: throwing it out beats tasting it. Spoiled food does not reliably smell or taste suspicious, and gut feeling is no substitute for an unbroken cold chain. Pre-cooked food that has stood unrefrigerated for more than two hours does not belong in the fridge, it belongs in the bin.
The trick that makes the biggest difference has nothing to do with cooking: freeze every fourth portion immediately and label it with the date. After three prep weeks you have a small stock of different meals in the freezer — and that is exactly what saves you on the evening when everything goes sideways and you would otherwise order in.
Second trick: do not run your cooking block on Sunday night, run it whenever you are home anyway and least in the mood to cook later. Meal prep does not work because it is efficient, it works because it makes the decision in advance. And if you would rather skip the planning entirely: the nutrition plan in the DOMISPORTS training centre builds you a week complete with discounter shopping list and portion sizes.
Two to three days — that is the recommendation from Germany's Federal Institute for Risk Assessment for cooked leftovers [1]. The condition is that the food was cooled promptly below +7 °C and that the fridge itself holds no more than +7 °C, better +5 °C [4]. Anything beyond that goes into the freezer on cooking day.
Because rice and pasta can carry Bacillus cereus, a spore-forming bacterium that thrives in lukewarm storage [5]. Its toxin can no longer be reliably neutralised by reheating. So with starchy sides the rule is: cool fast, keep consistently chilled, and heat all the way through when reheating.
As many as you will eat in two to three days, plus everything else frozen straight away. In practice that means four to six fresh portions and two to four for the freezer for most people. Build each portion around your protein target, roughly 0.4 g per kilogram of body weight [3], otherwise the boxes are full but empty of substance.
Some heat- and light-sensitive vitamins are lost during cooking and storage, that much is true. It rarely matters in practice: the gap between pre-cooked vegetables and no vegetables at all is many times bigger than the gap between fresh and pre-cooked. Cook briefly, cool quickly, seal tightly — that is all it takes.
Better not. Every reheating cycle means another pass through the lukewarm zone where bacteria grow. So only reheat the portion you are actually eating, and take it right through to at least +70 °C [5]. Leftovers of already reheated food belong in the bin, not back in the fridge.
How Long Does Prepped Food Actually Keep?