Is this a healthy physique for a belgian malinois? Health

I was wondering if this is a healthy physique for my dog or do I need to feed him more?
He is a 2 year old belgian malinois, I take him on about 2-4 mile runs 5 times a week.
He eats 3¾ purina kibble once a day. My parents keep telling me he is very skinny and I need to feed him more. I was wondering if someone with experience can give me some advice, thank you

Is that 3 and 3/4 ounces?If so, that is less than I feed my Beagle - split into 2 portions.
I do appreciate a lithe, well conditioned dog but personally, would like to see just a little more cover on those ribs.
He is a beautiful dog nevertheless.

I agree. Malinois are usually slim, but with that much activity I would increase his intake.

My Moose-dog had a very slender build (85lbs all leg with a long torso). He was eating 5-1/2 cups of Kirkland from the time he was 9 months until he was about 4 years old. Any less and his metabolism would burn through it in hours. After that, he ate 4-1/2 cups until he died at 15 years. He never had an ounce of fat on him. And he didn't run 2-4 miles five times a week.

I would increase in 1/2 cups amounts slowly until his ribs can be felt but not seen and his "tuck" is not quite so pronounced (you want to see his waist "tuck" in just in front of his hips, but you don't want to see his hip bones. And you don't want to see a change in his appearance before and after he runs - that's a sign he's burning through his reserves and needs more intake.

At 2 years old, he has grown as much as he will. But you should see some filling out in his girth. With the high activity level, you want to make sure he is getting enough food so he isn't burning everything between meals. He should be lean but not bony.