Getting enough calories

If you don't eat enough calories, you do not fuel your machine (body), malnourished bodies don't tend to succeed at doing very much. The better you eat, the better you feel the more you do. It's not really about "more", but rather "better", and when you eat "better" calories (ie: real food, low in sugar) you can still lose weight while eating more calories.

You will always lose weight on a deficit alone, you will lose FAT when you eat correctly.

EX: when I ate poorly (prepared foods, restaurants, bread, grains etc) I would lose on 1200-1300 calories- which is at a deficit, now that I have made huge improvements in my eating habits (over years) I can eat 1800 calories and still lose fat at the same rate. More food is better.

When I could not achieve 1200 a day I started to get a little wobbly. The body will power what it needs and if that is from muscle, the muscle will be sacrificed. You could be sacrificing your hair and your nails too. It took a while for my nails to stop chipping for instance.

Eat to your minimum at least.

Sounds healthy to me, and like a yummy diet. Maybe cook the eggs in some (real) butter, or some oil? Throw a handful of nuts or avocado on your salad. Have some red meat once in a while, it tends to be higher in calories than chicken. have a serving of a nut butter with your apple.

you should think about adding more fat! Add avocado, nuts/seeds, full fat Greek yogurt. Also you should work on increasing your intake overall, your diet makes me hungry just looking at it.

My days are something like this... along with clear tea, black coffee and loads of water.

Breakfast
2-3 eggs scrambled with vegetables topped with cheese and avocado OR Protein waffles with nut butter and maple and sausage.

Lunch
6oz chicken/beef/pork/fish, with several cups of mixed greens/vegetables
1 serving of fruit
1-2 oz nuts and seeds
1-2oz cheese

Dinner is some combination of 6-8oz meat and vegetables prepared with coconut oil or butter

And when needed i will have a scoop of whey protein powder mixed with water

I agree that the body works best when fueled. If you aren't low carbing, maybe add an english muffin or piece of toast with your eggs at breakfast or some bacon. You definitely want to get enough fat. Especially if you are eating higher amounts of protien. Fat keeps things moving if you know what I mean.

Anyway, nuts are great. I like full fat greek yogurt with a tsp of honey. Throw some fruit in there. Apples are great and contain a ton of fiber. You could also add some legumes or beans to your dinners. Good fiber and protein.

If all else fails. Eat some chocolate. I had several hershey kisses yesterday and they were delicious.

As others have said, calorie dense foods can be your best friend when you're trying to eat more. These are foods that pack a lot of calories into just a small amount, so they boost your calories quickly without putting a lot of extra food in your stomach.

This is a generic list and it's definitely not comprehensive, but anything here can be included in a balanced diet (as long as there are no allergies, medical conditions, obviously):
avocado
cheese
full fat dairy
Greek yogurt
ice cream
peanut butter (or other nut butters)
dark chocolate
less lean cuts of meat (including beef, pork, sausage, etc.)
seeds (chia, flax, sunflower, etc.)
nuts
olive oil
coconut oil
butter
beans and lentils
protein shakes, bars, and smoothies
hummus
beef jerky
cornbread
tuna
full calorie condiments
full calorie sauces & dressings
sour cream
guacamole
whole grain pasta
rice
bacon
whole eggs
quinoa
fruit and fruit juices
pretzels
bananas
scones
muffins (bran, blueberry, banana nut, etc.)
potatoes (sweet, red, gold, purple, white, etc.)
dried fruit (raisins, apricots, plums, dates, etc.)
granola
coconut
salmon
edamame
olives
honey
molasses

I like carbs too... There is no bad bread! But have learned food in reasonable portions, and living an active life were my 'key' to weight loss and now maintenance.

Getting a reasonable amount of nutrition will help your running program by the way.