After the New Year holidays, I feel very tired, heavy in the stomach, and generally apathetic. It's probably due to excessive alcohol and fatty foods.

You're right, after the holidays, the body often needs to recover, especially the liver. I came across some useful material https://genesishouse.net/blog/how-to-reset-your-liver-after-heavy-drinking/ , which tells you how to properly cleanse your liver after excessive alcohol consumption. The tips include gradual detoxification, restoring water balance, a balanced diet, and physical activity. Following these tips helps relieve heaviness, restore energy, and prepare the body for a normal rhythm of life. Regular monitoring and care of the liver prevent chronic problems in the future.