Rich in omega-3s and protein, salmon and oily fish are excellent choices to add healthy fats and calories, enhancing your weight gain and supporting heart health simultaneously.
You may even gain weight, but have a smaller physique ... Depending on how much muscle you want to put on and how quickly you want to gain it, add 5% to 15% to your maintenance calories.
Some people struggle to gain weight due to factors like a fast metabolism, which causes their bodies to burn calories quickly, leaving little surplus for fat storage. Genetics also play a role ...