I don't know where to start since this is such a deep topic. I'm nobody but someone who's actively tried to fix my health over the past 10+ years through varying diets and lifestyle changes. I'm far from a vibrant healthy individual, but I enjoy discussing health issues/solutions (probably to the annoyance of others). Read if you're interested, otherwise carry on.
Like many things we've been told, its mostly not rooted in basic biology and fails to mention what "health" actually is. As in, what is true health? what's the goal besides simple lab numbers on a report? As in what are we trying to achieve by eating "better", by exercising, by sleeping more, etc.
IMO, there is a good argument to be made that a high metabolism equates to "good" health. And many factors (stress, poisons, toxins, endocrine disrupters, diet, environment, etc) lower the metabolism.
Glucose (sugar) is one of the most basic energy unit for almost all cells. When you deprive your body of glucose/carbs, your body can/will breakdown your muscle tissue protein and turn it into sugar for your body to use. I'm not saying that you should down white sugar, but that you need a sort of "balance" of carbs/protein/fat, where simple carbs are much more beneficial for people with poor gut health.
T is formed by its most basic precursors: cholesterol, thyroid, and vitamin A. It's with these 3, the body can produce pregnenolone which then can be converted into further downstream hormones (progesterone, testosterone, estrogen, to name a few). Most adults are deficient in both thyroid and vitamin A.
This is a silly simplification of our biological processes. I can offer resources for further reading/listening if interested.