I think you're wise to not rely too heavily on meal-replacements, Serfr.
Considering you're only 110 lbs. (~50 kg) -- and, in light of your "rabbit food" comment -- it seems you don't eat enough calories. Not eating enough calories can certainly cause the low energy you're suffering.
Before my most recent bout with health issues, four years ago, I was able to go 12, 16, 18, or more hours between meals. Now, I'm lucky to make it six hours.
I don't try
to go so long between meals, mind you, but I sometimes get sucked into YouTube, this Forum, or other activities for long periods of time. So, I lose track of time and forget to eat. But, I'm quickly reminded to eat, when I finally stand-up!
While not really "food," I usually keep several LÄRABAR snack bars on-hand, for those times I either don't have anything already prepared or don't have any food in the house and I need to go shopping or pick-up something ready-to-eat. Otherwise, I'll be faint/lightheaded, when trying to drive somewhere.
I like the Apple Pie flavor. www.larabar.com/our-products/larabar/apple-pie
It gives me 200 calories and a boost of 18 grams of sugar. If I eat one and wait about
10-15 minutes, that's often enough to get me to a grocery store or restaurant and back home without having an issue.
Of course, it would be better if I didn't wait so long between meals and/or would have food prepared in advance. Especially since I have a pressure cooker that greatly reduces cooking time and trouble.
Anyway, if you're under-eating calories, I hope it's purely unintentional (i.e.
not an eating disorder) and you can become more aware of it and take some corrective/preventative measures.
Remember calorie density:
Food -------------- Calories per Pound
Vegetables --------- 100
Fruit ---------------- 300
Unrefined Carbs --- 500
Legumes ----------- 600
Fatty Protein ----- 1,000
Refined Carbs ---- 1,400
Junk Food -------- 2,300
Oil/Fat ------------ 4,000
A more detailed chart can be found at bit.ly/2FCUbFr