I find that while relying on fat metabolism as the dominant source of energy blunted my hunger, I was dazed and fatigued - literally dragging my heels during the day. My mental acuity and athletic performance skyrocket in the presence of ample carbohydrate at the expense of satiety. Reducing sugar by relying mostly on starches like potatoes helps to control mood and energy swings. With that said, if I don't get at least 50g of fat in, I feel like a bottomless pit. I have binged on kilos of carrots and felt ravenous despite a horribly distended stomach.

I tried reducing my carb intake along with everyone else when low carb paleo was the way to go for fat loss and performance. I had enough energy but my moods were always stable at a very flatline mode. I never got really unhappy or really happy just sortof was. If I ate an apple I would totally freak out into oblivion. I also had major carb binges about once every two weeks on candy and sugar.

Maybe it's just me not having enough self control but I really tried doing low carb. I don't know of it is sustainable in the long term for me. I actually have gotten more and more active as of late and I've stopped restricting carbs while trying to minimize fructose and I have felt better.

I sleep way better with the majority of my carbs being at dinner. I do fine fasting as long as my meal had a decent amount of protein and veggies. I feel better in the gym.

It is most important that people do not become dogmatic. If low carb is working now, that doesn't mean when you start feeling like crap later you can't have carbs ever. Be cyclical. Adapt. It's the human thing to do.

Ray peat thinks burning FFAs is stressful and burning glucose is anti-stress, you can read up on some of his articles to get more into that as its pretty indepth.

Personally I've tried lower carb, intermittent fasting etc. and my biggest issue was stress due to my living circumstances, any little thing could set me off into a rage during these times. My body temperature was also a tad low and I had various other minor problems during this time(gum pain and stomach aches being the biggest two).

Switching to sugars as my main calorie source, limiting fat and eating frequently has been a life saver for me. Been experimenting with it for a couple months now and I've yet to have one flip out(can't even remember the last one I had), my gum pain disappeared pretty much over night, stomach aches are gone, skin is extremely clear, body temperature is in the optimal range and I'm actually gaining a significant amount of muscle after trying for so long.

The people who claim that burning primarily fat leads to higher energy and mood stability obviously have never tried a very high carbohydrate diet that provides enough nutrients based on my experience imo.

I usually eat a moderate-carb, high-protein/fat menu but yesterday I went whole-hog (sorry, I couldn't resist) on some ham. Since I ate so much ham, I skipped the salad and vegetables I usually eat with my main meal.

The result is that I clearly lost weight overnight. There's a tell-tale feeling I've come to recognize and it was strong this morning. I don't use a scale but my clothes and the measuring tape I put to my waist agreed it was a good night. Not to mention that when I walked my dogs I felt light on my feet and very high energy.

This has happened consistently. With my combination menus, I lose fat very slowly and steadily and it's a good method. However, on those days when I'm hungry for meat and it's my dominant food, I lost about a week's worth of fat in one night and it doesn't come back when I return to my usual approach. It doesn't even have to be the whole day; yesterday I had yogurt and fruit in the morning.

To complete my answer to your question, full-time VLC doesn't work for me. By the 3rd day I'm climbing the walls with cravings for carbs and it's not my healthy, moderate carbs that I crave. So for me, VLC every day is a recipe for binge eating. But a day or two per week with less than usual carbs is a powerful fat loss technique.

I have panic attacks, low-blood-sugar-crying, and hunger (despite loads of calories) with 30-50g carbs/day, and I'm fine at 70-90g carbs/day. It's not worth dealing with that for three whole weeks in order to gain some mystical benefit when I'm happy at my approximately 80 g. There are too many other things I'm trying to fix (leaky gut from celiac disease, depression and anxiety from the same, and my career which is on the skids from all these health problems). Also, I haven't seen anything compelling that VLC is preferable to the generally low carb eating I'm doing.

I think that for me, the best plan is to listen to my body and see what it wants me to eat. I can't do that if I'm eating by prescription. I also want to focus now on repopulating my gut flora, and that requires foods that also contain carbs: onions, sunchokes, apples, oranges, etc.

"So I'd appreciate hearing the context, what did you try and do to switch to fat as the default low-activity metabolism and how did it fail?"

I ate fat and stopped eating carbs just like every other person who switched their bodies primary energy source to fat, and it has never, nor will ever 'fail'.

Human beings do not need to 'ingest' carbs(glucose/fructose/sucrose/lactose/maltose/etc) in order for glycogen to be found inside muscle tissue available for use during anaerobic activity.

This has been proven time and time again in scientific studies but more importantly in the lives of millions of human beings (possibly billions or tens of billions actually).

And to answer the headline question 'Does fat metabolism not work for you?' - That is like asking if osmosis does not work for you. There is not and has never been a single human being in which fat metabolism does not work.

Ray Peat full of shit

I find that I don't eat one way (high fat) or another (high carbs) consistently, every day. Depending on how I feel, and how much I have exercised, I change.

Usually if I have a day where I am feeling super hungry and hollow, (usually the day after a lot of exercise) I go with a high fat day, and that works. If I feel okay, then I don't go super high with the fat, and I feel fine too. I just kinda adjust based on how I'm feeling. Hope that makes sense.

I prefer a low fat, high carb/protein diet. I know this is against the core tenets of paleo but it's what works for me. I ate a high fat diet from the winter till May and I wasn't feeling too hot in the gym or during running sessions... I just started eating more fruit and sweet potatos in favor of fatty meat and coconut oil and I feel like a new man. Also, fatty gas smells ghastly.

It's difficult to understand what the question really is in that fat works for everyone, no exceptions, now it may be blamed by some as the reason their diet isn't working, though this possibly comes from denial and a reluctance to cut carbs.

Natural dietary fat should make up a large proportion of a healthy diet, there are no if's or but's on this.