I found this article. It’s written in Japanese, but it is about speeding up your metabolism. It says the more lactic acid bacteria and amino acids you take, the faster your metabolism will become. The most common food that contains lots of lactic acid bacteria is yogurt. Amino acids can be found in meat, eggs, beans, etc. So you just have to eat lots of yogurt and high-protein foods according to this article. If you try this diet, please let me know if your metabolism gets faster!