Fit, skinny 9yo vomiting after exercise - exhaustion?

[SoTiredSoTiredSoTired]

DS9 is extremely fit, runs 5km up/ down a steep hill before breakfast each day, does 30 minute swimming lessons that are laps of a 15m pool a few times a week. Eats large amounts, about 2/3 of what his very fit Dad eats. He has ADHD and is medicated, the exercise helps with everything, particularly running before meds have kicked in for the day.

He's also below 0.4th centile for BMI (98th centile for height, 9th for weight). After swimming lessons in the last few weeks he has been pale and has vomited on a few occasions. It looks like he's reaching very low blood sugar and is exhausted.

He's already eating about as much as he can fit in, volume-wise, he absolutely hates artificial-tasting or fatty food, and he is dairy allergic so all those protein breakfast drink things don't work.

Has anyone dealt with this kind of thing and did you find a solution that worked?

Exercise induced nausea is common in high intensity endurance sports such as swimming and cycling. Speak to his swim coach about how it can be managed. Ideally he should leave at least 2 hours between eating and swimming, and have some easily digestible carbs right before, and possibly during the session. Gels are ideal for this but appreciate he might not like them if he doesn’t like artificial tasting foods. Dried fruit, haribos, jelly babies are also good.

Is it only after swimming? I understand you day the exercise helps his ADHD but that's an awful lot for a 9 year old to be doing, especially running fasted each morning. Does he do this off his own back or do you encourage it for ADHD management?

I would suggest seeing the dr to get this checked out. If it's only after swimming could it be the pool is dirty or he's swallowing too much water? Does he swim very vigorously?

I'd get him to the Dr

Thanks all. I'll try dried fruit, haribos and jelly babies and see if that makes a difference.

Dr is useless, hospital system is broken (where we are makes the NHS look very very functional).

I agree it's quite a lot for a 9 year old but in the hour or so before meds kick in, he can't eat (sensory issues) and can't function at all (think chimpanzee on acid) so getting him moving, out of the house, is the only workable solution. And he loves running and swimming, and is far too dyspraxic to do any other form of sport.

I think the going pale and vomiting is an exhaustion thing because he's got like this once or twice when just exhausted (i.e. with not so much exercise), and swimming happens at the end of the day. The pool isn't dirty and he's not swallowing water as far as I know (I go swimming with him from time to time so I'd probably know if he had particularly bad technique).

I think it would be harder to get exhausted in a 15 m pool, that's tiny so you are touching the ends very frequently to get a brief rest. It's probably more about swallowing water or timing of eating. Would he eat some nuts beforehand to help?

I can certainly give it a go...

I should also have said his metabolism is through the roof. 3 large meals a day, frequent large snacks, he's permanently really hot. The ADHD meds get metabolised extremely quickly (one is supposed to last about 12 hours, it lasts 3, the others are supposed to last about 6 hours, and last 2). He weighs 25kg and is skin and bone. Which makes me think... thyroid? I probably should've thought about that before.

I’m thinking thyroid. I got quite ill and lost lots of weight before being diagnosed with Thyrotoxicosis. Felt sick and shaky, sweating and generally unwell. Graves Disease later.

You are letting him exercise too much compared to the amount he is eating especially if he is exercising starved . I would put a stop to this.

His dislike of certain food types ‘fatty food’ makes me think of an eating disorder and something called Red S .

Some of his mood and hyperactivity issues could be related to the metabolic changes rather than ADHD .

RED-S (Relative Energy Deficiency in Sport):
RED-S occurs when there is low energy availability—the body doesn’t get enough calories to support both exercise and normal functions. It can affect both females and males.
Symptoms and effects can include:

• Fatigue and reduced athletic performance
• Increased risk of stress fractures and other injuries
• Menstrual irregularities or absent periods (in females)
• Reduced testosterone (in males)
• Poor concentration and low mood
• Frequent illness due to impaired immunity
• Reduced bone density

It is treated by increasing energy intake, reducing training load if necessary, and addressing any underlying eating disorder or nutritional issues, often with support from a sports physician and dietitian.

I don’t have any advice but I am similarly very slim like your son with a fast metabolism. As an adult who’s has two children my bmi is still below 18 I also feel very shaky and faint after intense exercise and have been known to feel nauseous/ vomit.
I think it’s just a case of our bodies have no reserves so once the body has used all the energy available from food it has nothing left to take and you end up feeling depleted.
Sweets often make it feel worse for me but carbs like crisps, crackers or toast helps although not very nutritious.

Thanks @Gonnaeatalotofpeaches @LittleMonks11 I think both of those are quite likely. Thanks also @olympicsrock - this sounds like it could be a factor, secondary to what @Gonnaeatalotofpeaches and @LittleMonks11 are talking about. I've taken it on board and am trying to cram more calories and protein in where possible, though I think we really need to address the issue of metabolism first - which may or may not be something that can be solved.

@olympicsrock I think less eating disorder, more ARFID-like sensory issues around food. He can only eat when medicated, i.e. when meds have taken the edge off the difficulties inherent in tasting, chewing, swallowing etc. Which is also why he's going running before breakfast, trying to eat breakfast within about an hour of taking meds will just make him gag.

Regarding the ADHD meds, that is normal. My ADHD psychiatrist told me about that before I started taking them. I’m late 50s and have a normal metabolism and have experienced exactly the same thing with the meds.

@dizzydizzydizzy He was like that before the meds! They have made it worse but he's always been a fast metabolizer.