Gaining Weight

I went through a similar situation as you. The absolute key is going to be to have consistency in whatever you do. Short stints of healthy eating and exercise and then falling back into "bad" (not productive toward a better physique) habits won't help you achieve the body you want, so try to make lifestyle changes manageable and realistic for you to carry out.

If you don't want to make significant dietary changes, then I can boil my advice down to, "Eat more protein and lift weights regularly." If you want some more details, I'll delve into it a bit below.

First and foremost - you probably need to eat more. I never realized how much food you have to eat to gain weight until I started being mindful of calories. To gain significant weight and muscle (for the average male our age), you need to eat about 500-750 surplus calories a day. I'll explain as best as I can.

First, find a total daily energy expenditure (TDEE) calculator. You can find one simply by searching "TDEE calculator" on a search engine. This is an estimated value of how many calories you burn simply by doing your daily activities (not including workout). For you, I'd wager a guess it's probably around 2000-2300, but I could be wrong.
Add the amount of calories you burn doing exercise (probably around 200-400) to your TDEE, and that is your daily base calorie demand. Add 500-750 to that and that is the calorie total you need to shoot for every day. Simply look at the calories in the food you're eating on average and shoot for that. I found that the "MyFitnessPal" app on phones (or they have a webpage) is very helpful. They have a really simple tool for counting calories and grams of protein.

Second, you should try to consume more protein. I always aimed for at least 1g of protein / 1 kg of bodyweight. If you don't eat meat (I don't), I'd check out some protein powder options. They're affordable and really helpful. Additionally, eggs, yogurt, lentils, and beans are a good source.

Third, implement a workout plan and stick to it.
If you have a local gym, see if they have any options for trainers. Sometimes they can be a good resource for helping you learn how to do proper lifting form (for bench press, squats, and deadlifts). I've played with a couple of workout plans over the years, and I saw good beginner results from a couple of them. One is called "Starting Strength" - https://physiqz.com/powerlifting-programs/starting-strength-routine/
It's a very manageable program. It only utilizes basic full-body movements: the squat, bench press, and deadlift. These so-called "core lifts" are the key to a strong core and base for working out.

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Obviously this is only one way to approach the subject of "gaining weight," but this is one that I personally found to be successful. I went from being a very skinny high schooler to being a (not to brag) muscular and strong firefighter.
It's possible to gain weight and strength in other ways, but this is the way I found to be most effective.
If you have any questions about this or need any assistance, don't hesitate to reach out to me. I'm pretty passionate about working out and helping others with fitness, so I'm always available. I was a beginner with ABSOLUTELY NO KNOWLEDGE ABOUT LIFTING only 4-5 years ago. There's no shame in being new at something and not having knowledge about it.
Good for you for making a thread about this. It's not easy to make lifestyle changes and maintain them, but you'll be much better off in the long-run feeling good about your health and your body.

 

I’ve been working on losing weight myself. I wish I had the opposite problem.

 

I think TJ pretty much nailed all the basics. I will add that some gyms have trainers you can talk with any time for free, and some charge you extra. Also your normal doctor can also be a good resource for you to use to get started.

 

Eatn a mix of carbs and protein base diet
Gaining too much weight is Not healthy
In the long run .