I have a lot of friends and colleagues who cook for 2-3 days and just keep reheating the food whenever they need it. However, there are some foods which I would like to bring to your attention, which should never be reheated. Not only does the nutritional value of these foods wanes with repeated heating, but with these particular foods, the molecular structure of the substance changes to carcinogenic or otherwise poisonous after reheating, so it is best to avoid reheating.
1. Beets
2. Potatoes
3. Eggs
4. Mushrooms
5. Rice
Reheating of these foods produces altered protein structures in eggs and mushrooms and nitrites in beets and potatoes, both of which are potentially carcinogenic for humans. This was evidenced by many large randomized studies published in the last 10 years. In addition, reheating rice and potatoes can cause botulism and other bacterial diseases.
In general, to avoid decomposition of food, try to eat what you have cooked right away or at least within 24 hours, so that the leftovers will not become a breeding ground for bacteria and fungi. I encourage you all to cook every day if at all possible. It’s not easy but at the same time it can be a very therapeutic de-stressor and a chance to be mindful about what you are going to eat, in terms of nutritional value and portions. If it absolutely impossible for you to cook everyday, at the very least tightly seal and refrigerate or freeze the leftovers in the glass or ceramic containers.