I have the opposite problem. I'm 185cm tall and weigh only 55kg. I just physically eat enough to gain weight without getting sick and overfed. I always see people talking about how being skinny is supposedly better and more acceptable than being fat, but in my personal experience I've often been ridiculed for my body type.
I've seen people who want to gain weight use supplements they call "mass gainers" or "hypercaloric shakes" or things like that (the name depends on the country), but they're usually made of basically maltodextrin, dextrose etc, especially the cheap ones. the person beats them on the mixer with either water or milk, and then drinks one or twice a day. with two shakes, you get an extra easy ~240g of pure fast-absorption carbohydrate in your diet. they're basically liquid candy. they're delicious because they usually also have artificial flavoring and sucralose, despite being almost pure maltodextrin.
huge bodybuilders use these "mass gainers" shakes to try to reach very high calorie goals (sometimes 6000+ calories) without having to getting sick from eating or to stuff themselves. drinking liquid calories is different from eating solid calories. they're super easy to digest, convenient and you don't really get any satiety from them. it's often the opposite: they make you more hungry a couple of hours later when you get the "sugar crash", despite having just drank all those calories.
the cheap ones do the job, because the more expensive ones have extra protein and amino acids, but who cares about protein when you're trying to gain weight? to gain weight you don't need the extrar whey protein / casein calories, the pure carbohydrate from maltodextrin with flavoring does the job and does it very well.
in other words, people who want to gain weight and have a common mixer in their homes and some extra cash to buy cheap maltodextrin mass gainers, they have all at their hands to do it if they really want it.
the bad side: this makes people gain fat. and the more fat they gain, the closer they get to their personal fat threshold, and the more insulin resistant they become. unless the person were dangerously overweight, there's no reason to do that.
many people who wanna gain weight, actually wanna gain muscle, but they don't know it. gaining weight by gaining muscle is way more healthy. it's achieved by resistance training (gym, calisthenics etc), lifting heavy stuff and having a high protein diet. and the ultra-caloric mass gainers shakes can be a help too if the person has a hard time eating enough food.
What are the tricks you can share when it comes to losing weight?
Maybe focusing on lean protein and fiber on most meals? like fish and salad for example.
some people do 3 meals a day, with basically fiber and protein on the first two, and on the third they also eat protein and fiber but add some extra carbs and fats.
sources of salad could be any plant that is low-carb, for example leafy greens, vegetables in general, broccoli, kale etc...
sources of lean protein could be any animal that is low-fat, like salmon, 90% lean ground beef, chicken breast, tilapia, whole egg plus egg whites etc...
sources of fat could be avocados, eggs, nuts, ground beef, ribeye, etc...
sources of carbs could be blueberries, strawberries, boiled potatoes etc...
the less proccessing, the better. choosing fresh, whole foods helps a lot.
the only proccessing that is okay is cooking and seasoning.
extra proccessing after that, and tasty recipes tend to lower satiety-per-calorie.
sugar, flour and oil are the ingredients of most cheap processed food-like products that are available on supermarkets. by avoiding these three things and avoiding food-like products in general (which are not real food, but... products), you avoid a big source of weight gain in the first place. yes they can be consumed in moderation, but in real life people tend to overconsume them due to their high energy density, low nutrient density, texture, high palatability and high hedonistic potential.
also consider increasing your daily step count. your dog will love it if you take her for a walk.
I'll post some pictures with suggestions of low calorie foods...