Glad to see more skeptics on here. I do 3-day water-only fasts (not intermittent, just 72 hours straight) once a month. I get very little noticeable benefit if any. For me, the benefits are all "soft" benefits - willpower practice, realizing how little I actually need to eat, and very, very minimal fat loss if I walk for 8 hours on the last day.

Do wish all the magic, memory, autophagy, cancer-prevention, more HGH things were true though, but it does seem like they are blown out of proportion if there at all.

I wonder if the difference in experience might be related to how close one is to diabetes. A lot of people are in various stages of pre-diabetes, I've had fasting blood sugar measurements around 110 mg/dl, which is considered pre-diabetic. I've done keto and a little bit of fasting and experienced the seemingly magical effects.

Another possibility is that other people are getting into ketosis and you aren't. For me, the "recipe" to get into ketosis can vary a lot based on how much I've been exercising and eating carbs before I attempt to limit carbs or fast.

Purely anecdotal, but interesting coincidence - walked with friend yesterday, and he knows someone who lowered their blood sugar permanently by doing intermittent fasting. This makes sense, since fasting moderates insulin resistance. There is an ok book about it by a liver/kidney doctor. Can find if interested, don't remember name offhand. I found it to be good even though I am obviously not a fasting fanatic.

>and a careful review of research in humans as opposed to rodents seems unable to back either of them up.

Well, research might not say that IF or low carb have X or Y benefits. They might very well not have any major benefit by themselves.

But they very much say that lower BMI has tons of benefits, from heart to cognition.

So if IF and/or low carb helps you achieve this BMI, then you should (and would) have had those other benefits too.

Since I’ve gotten into serious cycling and learning about exercise science, I’ve realized how utterly ridiculous and harmful the low carb fad is. Carbs are the most efficient fuel you can give your body and usually the only source of fuel for your brain (by way of glucose). Being in a state of hypoglycemia frequently seems quite bad for normal people and outright dangerous and counterproductive for athletes. Having “bonked” on a few long rides because I didn’t refuel enough on the ride has really driven home the importance of eating carbs for energy. It’s a very unpleasant state to be in. I would never recommend a low carb diet to someone wanting to lose weight. Couple a low carb diet with fasting and exercise and your body will not just get energy from your fat cells, but also your muscles, and it can cause other unwanted outcomes like less healthy skin and hair.

One meal a day combined with keto helped me to lose 30 kg in 9 months practically without effort. As soon as I went off it (because of changes in life) I gained back 6 kg, now I'm at least trying to do OMAD but it's hard without keto, because the sugars make me hungry.

Not making claims about you, but simply skipping meals and eating more fat seems naive.

& other things matter, like gender, other genetics, and your macros.

YMMV, sure, because when I am low carb (less critical, more of a YMMV), high protein (critical), workout/lift (critical), count macros (critical) and fasting (less critical) I become the best version of myself. Mentally, physically.

I've had the complete opposite experience.

I'd be willing to bet you sacrificed micronutrients to meet your macronutrient goals.

Your low T could've been solved by adding a little maca root to your daily smoothies, which should contain all the essential micro-nutes your sacrificing to meet your macro-nute goals.

And yes, you can have a smoothie on keto with minimal high glycemic carbs that fulfills any deficits left by a strict high-fat diet.

I'm only advocating that you not knock something that is clearly working. Sorry you gave up on the holistic approach, but someone should've told you, it's not a solution, it's a practice. And the issues you had were a chance to improve your practice. You could accept the challenge, and expect to recognize and solve problems with constant adjustments to your diet, or keep up whatever your doing that works for you. Good luck.