Simplest way to gain weight fast

Here’s the simplest way I know to gain weight fast. 1) Monitor your calorie intake one day, without changing anything. 2) The next day, eat 500 calories more than is typical. So instead of eating 2500 calories, now you’ll start eating 3000 for the rest of the week. I suggest you do this, not by adding more to your meal size, but by adding a fourth and maybe even a fifth "mini-meal."  3) Go to the gym and start lifting weights. The value of weightlifting is that it puts on the pounds, but not by increasing fat intake. Rather, the weight comes from healthy muscle material!  Try going three times a week.