Yes @Allwelcone I think that what you eat is very important.
As @Uol2022 says it depends in what is causing the depression and of course when you are feeling low it can be a real struggle to take care of yourself. But too many processed foods for example are going to prevent you getting the right nutrients to help your body and mind.
When we are sleep deprived and/or depressed we are more likely to turn to simple carbs and sugar which can make us feel worse as they don't give us balanced nutrition.
Whole foods, lots of water, plenty of fruit and veg and high quality meat can help a lot, while avoiding alcohol (which is a depressant) caffeine and other stimulants which can disturb your body systems.
Overeating can make you lethargic and make it difficult to want to go outside and exercise as well as feeling physically generally crap.
Mood disorders usually need a range of different elements to help and eating healthily is definitely a positive.
Getting off screens and the internet is another element. Too much screen time has been linked with depression. It's better to read, try and meet with friends and family, spend time in nature and with pets, bake, play music or explore other interests. Pay attention to what helps you feel better (that's healthy) and try and add more of that gradually into your life.