Just found out this manga is a thing, and boy does this entire premise bother me. It seems long term unhealthy.
The page 1 art drastically shifts out of nowhere for his body build. And I'd been actual borderline obese, and in his supposed condition he would be middle overweight at worst.
Back in like chapter 1 or 2, he magically went down a notch on his belt. No, that takes a lot more time to happen, and you can't target specific areas to lose fat. Because while fat primarily gathers in belly for males, fat lowers evenly throughout body in general.
Then there's the exercises... sure these do work, but the number one most important thing is consistency. And MC pushing himself constantly is asking for trouble (though he has a lady friend to help him along I suppose). Both food intake and exercise wise. No comment on how exercises are shown being done, as it seems... very finnicky.
I mean look, squats done right should be targeting your abs and core anyway. Maybe less than planks, but still.
If you are a beginner or otherwise don't do any exercises, do some squats here and there. Maybe some pushups. Some fast walking. Just anything, strength or cardio. Because when starting out, any exercise is effectively both. And just once or twice a week to start. Doesn't matter how long or even pushing to failure, as long as you do them with attempted proper form. I'd even argue against pushing too hard to not be discouraged. Means less chance of injury and give time for stabilizer muscles to be built up too.
Then slowly reduce your food intake, both the amount of junk and the total amount. Slowly increase the time exercising, much later adding in an additional day where you do a set or two of things. Let your body get used to it slowly over time, so that it still feels natural. Might take months or even years, and longer to see some results, but it's a lifestyle change for longterm health.
It's also a time commitment. This is the other reason for even short exercise sessions and doing them somewhat consistently: not everyone has the time to do so, so anything during short time windows can be used. If there comes a point where more time is available, then a bit more time can be dedicated to exercise. If not, anything with some consistency is better than nothing at all.
I know because of the "cosplay with me" plot point, they have to move things along. But to say these at-home exercises will get you model-cosplay-ready is disingenuous even if you dive into them and do them to soreness and/or failure consistently. Coupled with completely cutting out snacks, all this is just asking for a hard rebound and unhealthy exercise stop later. Something I've seen multiple times, and experienced first hand.
Thanks for the tls and work though. And if you read it, my rant of sorts.