Food is the least important need in the game. starving your character drains 1% of your health for every in game hour, meaning it would take over 4 in game days for starvation alone to kill you. The solution to this is to starve yourself during the day, and only eat until your calorie count matches your calories burned before going to bed, which will replenish the condition you lost during the day. The only time you should be eating until full is if you have ample food from a hunt and you’re going for the well-fed bonus, which brings me to:

The well-fed bonus is granted after avoiding starvation for 3 in game days (food meter never depletes). It will allow you to carry 5kg extra. The moose hide satchel and technical backpack also allow for an extra 5kg each, but I don’t play story mode so I don’t know if there’s any way to get them. Aside from that, you need to manage your weight. Don’t lug firewood around with you or carry more than 2L of water, there are plenty of sticks for plenty of fires for plenty of water. Don’t take anything that you’ll find at your destination. Craft a bow and get good with it. The bow weighs less than half as much as a rifle, ammunition included. Stick to lightweight, calorie-dense food items such as crackers, tins of sardines and MREs. Weight from canned food and soda adds up, and it doesn’t provide you with enough calories to make the weight worth it. Cattail stalks are your best friend. Travel near rivers/lakes and harvest every cattail you see, leaving most of the heads behind. They are extremely lightweight and there are over 200 of them in forlorn muskeg. Six of them can keep you fed for a day if you’re starving yourself.