Could your body adjust if you separated your macros into meals? Like all carbs for breakfast, all fat for lunch and all protein for dinner? What would happen?

Most requirements your body needs are over days and weeks, so it would handle things nutritionally just fine.

As far as microbiome and bowel movements go? Most people need more dietary fiber than they’re getting already. As long as you keep that up so you’re regular and not gassy, you’d be fine.

After all, the human body is able to graze on roots and berries and eat a big fatty meaty meal once a week, or survive solely on meat and fat and water for 8 months of the year. Macronutrient division by meal is well within that spectrum.

What's concern about gas? I was under the impression fiberous foods lended themselves to gas production?
[off topic?]

Since you mentioned fiber, I decided to give a plug for wheat germ.
- I'd recommend sweet peppers and dried fruit (i like apricots) as snacks for fiber. still tastes great, is healthy, and will help with 'regularity', if needed.

I wonder what an all-fat lunch would even look like. Foie gras and fat bombs with chipotle mayo? Lol. I don't think it would be practical and at worst you'd have diarrhea every afternoon.

According to the label on the bottle, 50 x 1,400 mg soft gels of Kirkland Signature Wild Alaskan Fish Oil will hit 100% of recommended daily fat in take based on a 2,000 calorie diet, though you might eventually overdose on vitamin A (as retinol).
- Nothing says "bon appétit" like 50 gel capsules of fish oil.
Glass of oil
Shot of olive oil?
"Hey, what's for lunch?"

"A stick of butter."
i'd combine fat and protein into one and go to a brazillian steakhouse.
- Realistically, my meals are more like half a chicken for 1, big bowl of pasta with tomato sauce for another, and a big salad with too much caesar dressing for the third. I tell myself it's balanced but I figure those off days aren't great for me.

You would be fine, you could do it for a long time.

All carb meal: spike your blood sugar

All protein meal: no issues

All fat meal: no issues

Fat is totally processed by the stomach/~~large~~small intestine, none of it makes it to the small intestine. I've done a fat fast before, so I can tell you from personal experience, no issues.

Downsides: eating fat and protein before carbs in a single meal can reduce the glycemic spike of the carbs.

Upsides: since your keeping your carbs to one meal, you only spike your glucose once per day, this is a from of intermittent fasting/time restricted eating. You will actually see improvements in your insulin sensitivity over time.

Note: after the fat and protein meals you will feel full and Happy, after the carb meal you will feel quickly hungry. Carbs are not great for your health, and you can live very healthily without any carbs whatsoever.

Fat is totally processed by the stomach/large intestine, none of it makes it to the small intestine.

What order are those organs attached together in your species? In my species, homo sapiens, it goes stomach -> small intestine -> large intestine.
- good point! i got it reversed

Remember: most flour contains protein so no bread and enjoy your pure glucose for breakfast.

I don't know what would happen to your body, but i know these would be the worst meals you'll ever have

Carb meal and protein meal would likely be fine... but fat meal... 🤮
- It would be loose, I wouldn't expect someone to eat a stick of butter even though that is norm in some extreme diets. I'm more thinking along the lines of sometimes you eat 2 slices of bacon, sometimes you eat the whole pack. And yes, sodium would be another issue.
- Cheese chips and guacamole could be okay, but if you can’t have any protein or carbohydrates, that would be difficult.

That's kinda what it expects actually, because for the majority of human evolution we didn't have guaranteed meals at regular(ish) times like we do now and what we did have would vary wildly in nutritional value. there should be no issues except the... aftermath of certain meals.

Pain is just weakness leaving the body

flip protein and carbs and you'll likely be fine.

All carb breakfast would lead to a big energy crash for me around 6 hours after that bread-breakfast.

Breadfast
- There's fat in bread. An only-carbs meal is basically eating straight sugar (glucose).

Wait... This isn't how youre supposed to eat?

I think people could really get into the "10 slices of fairy bread for breakfast, half a pound of cheese product dipped in mayo for lunch, unseasoned boiled chicken breasts for dinner" diet if they gave it a chance

Pretty sure the fat meal will just become diarrhea.

Agreed that the all fat meal would not exit well. It also might overstimulate your gallbladder? I'm not sure.

Edit: and your pancreas would probably also be mad at you.

I highly recommend not eating your keyboard. The most commonly-used macros probably taste like finger cheese.

Does that fall under my fat heavy meal or my protein heavy meal?
- I think it's part of a, "stabilizer diet"

I don't have an answer for you, but I do want to say: great question.