To answer your first question, no, I've never not brought food along, even on a shorter trip.
I've experimented with different calorie intakes as well on trail. I'm 6'2" 175 pounds. Lean, with some muscle if you squint when looking at me. Also, I spent 3 years on an around-the-world trip after graduating college. I think that journey really affected the way I view myself and what I actually need on a daily basis, both to be safe, and to be comfortable. Mostly I spent time hiking in warmer temps through Mexico, Central America, South America, and Asia.
Anyway, this experience taught me to calorie load when I had the chance, and get by on far fewer calories, sometimes less than 1,500 a day, even on high-output days of 20-30 miles. I didn't have access to fancy meals or even many ingredients sometimes. I gave up being a vegetarian cuz I needed more protein, so I ate chicken, fish, etc. Sticky rice became a great favorite of mine. I could combine that with anything and make a meal. If I was going on a 5-day trip in Laos for instance, I would eat 5,000 calories or more the day before I left. Just eat and eat. Then I had a decent calorie store for the trip. I'm not sure if this is the healthiest approach, but I've also used it Stateside.
Back home in the States, I tend to carry more food since I have more options. I have a Caldera Cone, a Snopeak Titanium pot, and a titanium spork, so I have a lightweight set up, but lately I've been leaving it all home for the sake of simplicity and eating cold food. Uncooked beans, tortillas, avocados etc. I also live near an awesome store that has 2 full aisles of bins filled with organic goodness.
For a 3 to 5 day trip, my food weight is usually 1.5 pounds a day. However, if I take the calorie-load approach, I may carry less. For breakfast: oatmeal, brown sugar, and coconut oil. Maybe carry a few Clif bars. Various trail mixes with nuts, fruits, etc. Whey protein powder. I've been eating carob nuggets with mixed greens. A few crackers and cheese. I generally eat on the move and try to eat every hour or so. There are days I'll go several hours between eating, especially if I'm hiking in the redwoods near my home. Then I get lost in the Jurassic-like beauty, and tend to forget everything else.
Also on a side note, my GF has recovered from a horrific motorcycle accident that happened 7 years ago and nearly killed her. She's still rehabbing her body and mind. She's had 6 surgeries and constant problems with her knees, ankle, and back ever since. She's the strongest woman I have ever known and is back to covering 20+ miles a day. It definitely helps that she's 29 and in incredible shape. She is fanatical about her workout regimen and exercises 6 days a week. She's ignored doctors who told her she would never backpack again.
So I wish you the best in your recovery, and I think it's awesome you haven't let injuries prevent you from experiencing something you love doing. Peace.