Depends on the type of supplements. There are many liquid supplements that are actually used to keep older people fed who don't eat enough and would have need tubefeeding otherwise.

NO!!!! In the absence of disease or other condition, supplements are meant as what they are... SUPPLEMENTS! marketers have led you to believe supplements = meal replacements when this isn't the case. (i have a degree in sports medicine - just hear me out) most of the food we eat (outside of fast food) carries all of the vitamins and minerals and other nutrients we need for daily living. many of the nutrients cannot be synthesized by scientists. even the ones that can be man-made don't always function the same as it is found in nature. for instance, fruit juices such as 100% apple juice or orange juice are very good for you as they are rich in vitamins and minerals. however, you miss out on the benefits from parts of the fruit lost in processing and filtering such as parts of the skin. there are also phytochemicals that have been proven to provide nutrional benefits (although science hasn't come up with a nutritional value yet). the point is the synthesized version is never as good as it is naturally. im sorry you are in a bad financial situation as i am too. many times i eat 1 meal for a day. but i try to make it a good meal - a healthy cereal like cherrios, wheat pancakes, chicken livers, or a subway sandwich (if i wanna splurge!). i hope you understood my position. sorry for the length.

No there is much more to food than a few elements that you can find in supplements. You still need things like fiber and calories to fuel your body and keep it running and you will still set yourself up for ill health and injury. Plus supplements are more expensive than foods.

They are a food "supplement" not substitute

No they cant you have to combine them with food. They do help a bit with energy levels and such though.