Hi everyone I am new here.

Step1: Go on google, type "TDEE Calculator". TDEE = total daily energy expenditure. Based on your age, weight, height, activity level, etc., it will determine how many calories it takes to maintain your current weight.

Step2: In order to gain +1lb a week, you need to eat 500 calories OVER your TDEE. That means you need to be weighing your food on a scale and tracking everything that you put in your mouth. It takes 3500 calories for 1lb of weight gain, so that makes TDEE+500calories daily = +1lb per week.

This might be hard as you are a smaller person (500 calories for a 100lb woman is VERY different from 500 calories for a 200lb man), so I suggest you aim for a surplus of 10% to 20% instead - this is more realistic and you won't feel disgustingly full all the time. Perhaps you can aim for TDEE+250 calories = 0.5lbs of weight gain per week, or +2lbs of gain per month.

Using this system, you can clearly and accurately measure how long you need to do this for get to your weight goal (i.e. say you are 105lbs and want to get to 120lbs - Eating a surplus of +250calories daily = 30 weeks, which is just under 8 months time).

Lastly, look at this weight loss chart below (I know you are trying to gain but the idea is the same):


Notice how the daily weight fluctuates greatly, but the general trend is clear. This is how weight loss / gain is - due to uncountable variables (sleep, what you ate, how much you drank, when did you eat, when did you drink, what did you do today, what's going on with your body, etc. etc.). This is why I prefer weekly weight ins instead of daily weigh ins. Make sure you weigh yourself under the same conditions every time (i.e. right after you wake up, post washroom, pre breakfast).

The main thing is to be consistent with your diet and give yourself time to change. The longer it takes to change, the more permanent it is. Cheers!

Apart from the above super cool advice, it might be prudent to ask your Medical Practitioner that question too, illnesses can have unexpected implications or outcomes that justify due diligence to avoid undesirable outcomes.

That said look at checking in with your Dr with these fantastic dietary items
1. Flaxseed
2. Almonds
3. Coconut Oil
4. Cottage Cheese

What excercise type of routine are you doing and what frequency do you keep?? Are you a novice, or have much experience training? Do you do any Aerobics and or weightlifting?