A question on IF calculations and weight gain.
Alrighty. First thread I've created (lurker here) and I'm not exactly sure if it's in the right place, or if it's been asked before. Or if it's so obvious that it doesn't really need to be asked and I'm going to look like a complete moron.
Oh, well. Anyway...
To make a long story short: I'm trying to gain weight.
At 50 kg, I find myself a little too light for my height (165 cm, if anyone cares) and am looking to gain around 5 kgs at least as a start. However, being horribly vain as I am (come on now, fair's fair :P) I don't really want to just put on 5 kg's of fat. Recently, I've started going to a gym to hit the weights, but - obviously - I need to eat more, so I've upped my caloric intake.
Now, here's the part I'm trying to understand.
Using this calculator (IF Calculator) I worked out a thingy to up my calories to 2400 on rest days and 2800 on workout days (on a Upper/Lower split Mon/Tues Thurs/Fri). The calculations said I would reach my goal of 55 kg's by late December with a body fat percentage of 9% (current is around 5%).
My question is: is this accurate?
Now, I know things (genetics, dedication, workout intensity, something else I can't think of/don't know of) could play a significant role and nothing is 100% accurate, but what I specifically mean is: do I have to fast? Despite my best attempts at explaining it, alarm bells practically fill the house when the word "fasting" is mentioned to my parents. So, assuming I follow the workout plan and caloric intake, will I have the same/similar results, or will they vary?
Again, my apologies if this is in the wrong place and/or this question is stupid and obvious. I'm just kinda curious.
I don't think you have to fast. Those calories sound completely do-able in a given day, and would likely do the trick.
But if you want to fast, that's ok too.
I looked at the calculator and it's sensible enough if you're willing to accept a dependence on carb for most of your energy supply. Given your current body fat (5%), that's not unreasonable -- but it is a choice. If you choose to depend on fat, however, you will go through an adaptation process (Peter Attia describes his in some detail, at his Eating Academy blog), and he can still do significant strength-based workouts (he has a video of part of one of his workouts in one of the segments of his personal transformation series).
Depending on your genetics and epigenetics, you may or may not be carb tolerant. Phinney and Volek estimate about 25% of the population is carb tolerant. I have learned the hard way I'm in the 75%. IF is easy for me when I'm in nutritional ketosis; I am simply not hungry most of the time. In fact, I have to ensure I eat because though my stomach rumbles, I have no perceived need for food. I'm also using KBs for strength, and that's working well, too - just moved up to the next larger bell, which is significantly harder and I'm back at the sets/reps I started the smaller bell with.
So I think following the calculator's ratios is entirely optional for you. I think you will find following an IF-like pattern will be more difficult if you also follow their carb recommendations. But that is my estimate -- every one of us is a little different. Your best bet to find out out is to try. Keep records and then analyze, bearing in mind that one or two days is rarely indicative. One or two weeks is better.