Yes, it matters if you don't eat regularly. Breakfast is an important meal. You need it to get your fat burning furnace (also known as your metabolism) going for the day and you need to keep that furnace stoked by feeding it regularly. You shouldn't go more than 5 or 6 hours without eating except at night when you are asleep, otherwise your body starts to think there's a famine going on and begins shutting down your metabolism to conserve energy stores. Even if you're not hungry, eat a small protein snack to keep things moving along and don't make a habit of skipping meals. Once in a while is okay, but not on a regular basis. Skipping meals will not help you lose faster; it could have the opposite effect and make you lose more slowly or not at all...you need to keep your calories up to 10-12x your body weight daily and it's not a good idea to get them all at once. Same thing goes for your carb allowance; don't save it all for one meal. Spread it out evenly throughout the day.

A cup is 8 ounces liquid, but usually 4 ounces dry measure; it really depends on how dense what you are measuring is. For example, 4 oz. of shredded cheese is 1 cup, 8 oz. of water is 1 cup. Mushrooms aren't as dense as cheese, so it would take less ounces of mushrooms to equal a cup...probably 2 or 3 ounces. HTH