Gaining

Just wondering if gaining is harder if you start under weight

For me it was. I started 30 pounds below the average weight for my height, and even now I'm only at the average weight. The hardest part for me was finding time to eat a normal amount of food lol

Absolutely. My first few attempts at actively gaining, when I was younger and skinny, were mostly unsuccessful. I can remember bingeing like crazy for 6 months and only putting on 15 pounds. It wasn’t until I was 30 and “slightly chubby” that the weight started to stick.

So, this is actually a complicated question.

Two people who eat the same amount, we'll say 2,500 calories a day to insure no malnutrition, have a similar muscle mass to bone mass ratio, and are both similar in hormone palette, then yes. The skinnier of the two will likely struggle to gain weight compared to the bigger one.

This is mostly due to having more fat cells = easier to get fatter. But having all these things be lined up would be absolutely unheard of, so it is better to think of "harder" or "easier" as relative to the amount of effort a person puts into the task.

The unfortunate truth is that analysing one's gaining is a very math and monitoring-heavy process. So if you aren't able to just constantly stuff yourself it may be difficult to figure out what specifically plateaus someone.

Many people start skinny, though, ans get rather large.

I don't know how many years it took me to weigh 70 kg. At first, it was very difficult for me to gain weight. I would binge eat for weeks and only gain 2 kg. I mean, the main thing is to be consistent, don't give up, it will happen eventually, but don't be in a hurry.

I’d say it’s harder for bigger people to gain more weight than it is for skinnier people to get fat. That’s not to say it’s easy by any means it just takes a consistent calorie surplus to gain and the more active you are the more calories you need. This trend is just amplified the bigger you get, someone who is large needs like 4700 calories just to maintain their current weight. Someone smaller and is active needs like 2k.