As a baby I was really heavy and now I'm one of the skinniest dudes in my family.

They tell me stories about how people used to come up to my mother and utter the words "Gosh, I haven't seen a child as healthy as yours" and then I got into my teenage years and ever since have been on the skinnier side. I even joined my local gym and was committed to it for 4 years but eventually lost patience because it didn't work out for me at all, I gained a lot of strength but not much muscle and when I quit, it only took a month to return back to my old skinny self.

Now as a child till the 9th grade, I used to run a lot. Me and my friends, instead of picking up bats and balls, we would play tag a lot and it didn't take long until I became the fastest among my friends.

It got me thinking, did I actually end up with a runners body because I trained it to be that way as a result of what I did in my early days? As the chubby child that I was, shouldn't I be on the similar scale now as an adult?

2 Answers 2


The short answer to this question is NO.

With regards to your physique, your activities determine the shape while your nutrition determines the size. This works within certain genetic parameters of course, but these two things will determine what your body adapts to. Adaptation is key, because a body doesn't transform suddenly when its activities or nutrition changes, instead it slowly adapts.

So as a child your body adapted to these things. I'm not sure how old you are now, but if you are in your late teens to early 20's then it's entirely possible that your body still holds onto some of those adaptations (given that you did it for so long). An interesting example of this is Richard Sandrak (aka "Little Hercules") who trained rigorously from age 4 to 11 or so as a bodybuilder. Afterwards, he stopped lifting weights and purportedly only did cardio type activities along with a bit of bodyweight work. He's currently in his mid-20's and still has more muscle than the average guy.

That being said, you seem to be under the wrong impression here. You are by no means fated to keep your current physique forever. Your body will adapt to the shape and size appropriate to your activities and nutrition respectively. If you sought to build muscle for four years and didn't do so, then you simply did something wrong. You might have been training improperly, you might have been under eating, or both - it's hard to say without knowing more. Regardless, while the activities of your youth can contribute to your physique as a young adult, they are by no means the determining factor in your body's current physique.


This is essentially the nature vs nurture question, in which case the answer is always yes and no.

For example, if you grow up throwing a baseball, your humerus (upper arm) and shoulder joint will literally morph into a differently shaped bone than if you don't grow up throwing. This is called humeral retroversion.

It enables the shoulder to "lay back" like this: humeral retroversion

We know this is an adaptation because we'll see the pitcher's non-throwing arm not have that ability.

It's also where the expression "throw like a girl" came from. Because so many girls used to grow up not throwing, when they would try to throw something in adulthood, they'd throw it like a shot put. They'd push the ball since their arm couldn't move like above.

There are all kinds of adaptations like this. The Sports Gene does a phenomenal job looking at a lot of this, even citing research showing growing up playing tennis can make your dominant arm a little longer than the other!

I've only cited bone so far, but it's a big one. For many sports, if you can't get in the sports' positions, everything else doesn't even matter.

But there are all kinds of other things to entertain. Mitochondrial density, whether a gene is turned on / off (and whether the ability to change that goes away once we hit a certain age).

Depending on the context, yes, what you do growing up can dictate what you can do as an adult.

However, as the great sprint coach Charlie Francis said, "You can't turn a donkey into a thoroughbred."

For instance, something you do see in the pitcher's non throwing arm is an unusual ability to easily dislocate the joint. Something called a sulcus sign. 61% of professional pitcher's have it, with 89% having it in both arms. (More info and videos.) That is, they tend to have an unusual level of mobility to begin with.

Many, like insane parents, take an example of what-you-do-while-younger-impacting-adulthood to think they can just practice their child into athletic stardom. It doesn't work that way either.

Note: I used sports because it's often the easiest to relate to, but it doesn't stop there. We're learning all kinds of things about metabolism too. If a person was obese at one time, that can seriously and, as far as we can tell right now, forever, change their metabolism, making them always more likely to become obese again in the future.

Lastly, while most remedial it is not the least important: habits die hard. If you get into a habit of running or being active young, that's only going to help you look more like a runner when you're older. After all, if nearly 3/4 of the people around you are overweight or obese and you're not in part because you're active, well, you sure look like a runner than most! (Even if you don't run at all!)

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