I typically don't weigh out each meal, but I do weigh my entire food bag. It usually averages out to about 1.66 - 2lbs per day. Anything more than that is too much. It's important to make smart food choices. When I say smart food choices I don't mean (necessarily) the healthfulness of the food item, but the calories per ounce it provides. It's important to pack calorie dense foods because it saves space and weight in your pack.
The first step to reducing food weight is to remove all the factory packaging and substitute for ziplock bags (be sure to use freezer bags; they're more durable). If you like to carry pre-packaged dehydrated meals, like Mountain House, the packaging can be heavy and bulky. Swap it out for a ziplock bag to save a couple ounces (remember, ounces add up to pounds).
Here's a tip: to add calories to your dinner, bring a small bottle of olive oil to add to the meal. This goes for dehydrated meals as well as enhanced meals like Hamburger Helper or Zatarain's It will essentially have the same effect as butter to the texture of the meal and enhance the flavor quite a bit. Olive Oil is a very calorically dense food at 120 cals/15 grams.
Freezer Bag Cooking
If you're unfamiliar with Freezer Bag Cooking (FBC), check out this post. Dehydrated meals that you reconstitute with boiling water is a great way to save weight. For example, a 12 oz can of chicken, when dehydrated will weigh 1.5-2oz. Across multiple dinners, that saves a lot of weight. If you have the time, dehydrate some veggies and a meat and add it to rice or pasta. If not, pre-packaged backpacking meals or enhanced meals work well too.
Should you pack extra food on a trip? Short answer, no. Typically on a 3 or 4 day trip, if you run out of food it will be on the 3rd or 4th day. You may get hungry, but you won't die. Your body has fat to metabolize. Personally, I don't bother to carry the extra weight. If you're going on a more adventurous route where it's likely you could get lost or uncertain how long it will take, I think it's a good idea to prepare for the worst case. You be the judge.
If you have extra food, don't feel bad. Hikers love to eat and I'm sure you will have no problem giving it away on the trail if you dont want to pack out the extra weight.