I honestly don't know much about typical Japanese eating habits, but could this be more about what they're eating instead of those carbs?

Like, if it's anything like the US I wouldn't be surprised to see numbers like this simply because the non-carb food is probably mostly meat in the case of men and mostly veggies in the case of women. I don't really have numbers on percent of meat versus veggies in a diet on average by gender, but there certainly seems to at least be some culturally imposed presumptions of men gruffly devouring steaks and women laughing at salad.

If most of your diet is meat and you cut back on carbs only to eat yet more meat, you're probably not going to be as healthy as someone who eats a ton of veggies. Likewise, replacing vegetables with carbs probably sucks for your health.

this is an interesting study to see. it's a survey of mortality among japanese men and women and how their diets correlate with causes of death

personally, i'm not sure i find this a compelling argument against keto for men. their finding is increased mortality if their carbohydrate intake is <40% of their total energy expenditure. 40% is a pretty high bar for keto, where you're looking to be at 5% at most (at most, 20g of carbs a day = 80 calories; 2000/80 comes out to be about 4%)

so probably, a lot of these people aren't in keto, which i would consider a clinically relevant distinction (we don't know for sure, since the nuances of the population's eating habits weren't published)

second, i don't know that i would want to try keto in japan? like, i don't know what their fat sources are, but... if i ate enough fish to sustain myself on keto, i'd get fucked up by mercury. and like... idk how much better it is? but a lot of my food comes from beef and dairy, which i don't think are as commonplace there (i know it's bad for the environment. i know. i know. i don't want to starve though. i'm sorry)

i'm not that educated on how food looks in japan. but it strikes me as very keto unfriendly. depending, this might be a huge factor, or a minor one, but it's hard to say without clarification

anyways, it's an interesting post from a transmasc point of view. i originally fled carbs while running on estrogen. i feel like i tolerate them better (not well, per se) on testosterone. there's a definite challenge on keto to eat enough calories on testosterone, especially now that i work out and i'm trying to build a considerable amount of muscle

but at the end of the day, i still feel better on keto, and now that i've figured out how to reliably provide like 3k calories in fat, i'm doing pretty well