He is working with coaches. With his goal of getting his fastball into the 90s (currently at 84-85mph) and hitting the ball over the fence more, the primary feedback has been adding explosive weight.
Here is an example of a pitcher lower body workout from Tread Athletic, who trains dozens of MLB pitchers as well as amateurs who are hoping to get to that level: https://www.youtube.com/watch?v=zkWWUHsw62M
He does like to eat, although he sometimes has difficulty finishing everything we make for him. I feel like a big part of the difficulty in getting him bigger is that he still hasn’t quite matured physically. I just don’t want to rush that, even though he feels like he needs to get there by spring to get the college offer he wants.
I have been surprised at how aggressive baseball coaches and trainers are with weight lifting programs now. I played football and baseball, and I wrestled in high school 30 years ago. I remember people telling me that my football and wrestling routines wouldn’t be good for baseball, but now those same routines (heavy bench press, squat, deadlift) are used a lot for baseball. The caveat is that baseball players have to be VERY careful not to lose their flexibility. My sons do pretty extensive stretching and hanging from a bar (3 minutes) pretty much every day.
With all due respect, “medical science” (especially over the past 5 years) has been found to be much less science and much more manipulation, deception, and profit chasing at the expense of people’s health.
During the 5-7 years we attempted to get help from doctors (personality altering steroids, progressively stronger inhalers that would only provide temporary relief, and other bad ideas), we were awakened to the existence of a diabolical system of healthcare that we’ve chosen not to be part of. Our last two children were born in our bedroom with a midwife and have never seen a doctor. They are by far the healthiest of our 9 kids.
Bodyweight will absolutely help him with speed. Just like a punch, an effective throw starts with the legs, amplifies through the hips and ultimately gets “thrown” by the arm and having more energy in the kinetic chain by shifting additional weight in to the motion will amount to harder, or faster pitching.
A few things to keep in mind are that adding bodyweight will alter his mechanics and his overall athleticism and endurance will need to be trained to keep up even if the gain is muscle. His mobility may change depending on how much weight he gains, but even nuances change form and circles back to his throwing mechanics.
All fairly easy to address. Just via the nature of growing up, kids play new seasons at new body weights and even limb lengths for years.
However, keep him practicing, and if the goal is moving up competitively hire a coach to monitor his pitching and work in real time on adjustments.
Regarding weight gain itself, just feed him more. It doesn’t have to be a calculus equation like it often seems when researching monetized “programs” out there.
Please, I implore you, ignore the fringe diet advice you find on these forums. We aren’t talking about a specialized bodybuilding show prep for 6 weeks.
He needs carbs, fats and protein. Feed him healthy, nutrient dense food and make his servings a little bigger each meal. Aim for about 1-1.5 grams of protein per pound per day, and protein powder is fine to get there.
If he’s not using creatine, it’s worth considering. He will put on weight quick.
