Sounds like her own personal opinion. There's no real historical basis for these foods being reserved for gods. Alcohol and bread have been consumed by humans for thousands of years. You get sick when you eat gluten because you have celiacs, but various kinds of breads have been a staple in many, many cultures. Alcohol as well. In ancient Egypt they used the alcohol to make bread, and the bread to make alcohol, and so on. There were entire religious festivals and cults that revolve around the consumption of alcohol or bread. There are myths that these things were taught to humans by the gods so they could live better lives (along with things like agriculture in general, house building, and so on).
Sweets are a bit different, in that they weren't as easily accessible for most people as they might be today, but they certainly existed and were eaten as treats. To go back to ancient Egypt, honey was a popular sweetener for the rich, while the poorer folks used mashed date paste to sweeten their foods.
Which is not to say the gods were not offered such foods, spirits and ancestors as well. Bread and beer were a huge ancestral offering in ancient Egypt - because that's what people enjoyed in life! Bread, alcohol, and sweets were offered to deities across many different cultures - as were fruits, vegetables, meats, milk, water, butter, olive oil, and so on. (And of course non-food things, like incense, flowers, and votive offerings.) In many traditions offerings were not wholly for the deities, but a portion was offered and other bits shared in a communal meal. Or, in some practices, the whole thing was shared as a meal after offering. For example, in Greece, for many deities an animal would be sacrificed to them, the parts that weren't so edible would be burned for the deity, the meat would be cooked and passed around to the people. (Other deities would consume the whole animal...) For some populations of Greece, they didn't eat meat often outside of these celebrations, and would rely more on bread and other staple foods. The Orphics of Greece wanted to replace animals sacrifice with sacrifice of cakes shaped like animals - again, with some burned for the gods, some eaten by the devotees. The shared meal is a huge thing in a lot of religions, so they would not offer something that they would not consume.
But I think what we miss, is that many ancient pagans often advised against overindulgence on a regular basis. Getting totally drunk once in a while? Well, sure, it's for Dionysos! Getting drunk all the time... not so great. It's like looking at the way a lot of us eat today. Cheap, processed, sugary foods are abundant. Sometimes they are all a person can easily access. So, we eat too much of those things. People who drink too much run into their own issues. Studies have shown that drinking, say, wine in moderation is good for you in some ways. It can be bad for you in others. (Kinda like most things on earth, I would guess.) Our diets and what is available to us is a bit different than, say, how it might have been 3000 years ago. Your friend might decide to deal with this by not consuming certain things and giving them to the gods, instead. It's a fine personal choice if that's what works for her! But no, there's no historical basis for it - and it wouldn't fit into the way a lot of pagans practice, again, going back to the shared meal bit, or other reasons (whole cults around bread, beer, bees, and such).
I sing of you, blessed, night-winged Dream, Messenger of things to come, greatest prophet to mortals, in the quiet of sweet sleep you come silently and speak to the soul.