Does fat slow down protein digestion?

(M) #1

I know fat slows down carbs but how does it affect protein digestion and absorption without carbs? For example if I eat lean fish with 60g added animal fat how will it affect fish digestion?

(Bacon enough and time) #2

I’m not sure what “fat slows down carbs” means. but I haven’t heard that fat has any effect on protein digestion in any way. So putting butter on your fish won’t have any effect, other than to make the fish taste better and to give you that much more energy to fuel your life.


Fat slows down everything, and that’s a massive amount of added in fat! You’ll get the protein in either way, but that’d probably be hours later. When I do my preworkout meals and I have more time in between meal vs workout I’ll buffer that with more fat, and since for many (I’m one of them) that can just shy of tell you how much food is in my stomach in grams by the way I feel during the workout, doesn’t take a lot of fat to really slow down digestion. I think that’s one of the bigger movers on keto keeping people full for as long as it does.

(Joey) #4

Hmm… I was under the impression that the order of digestion/metabolism is (first) alcohol, then refined carbs, unrefined carbs, protein, then last of all fat.

So I didn’t think eating fat slowed down anything else … but that fat gets digested last of all if any of those other macronutrients are present.

Having said that, besides fat, we need to consume some amount of protein. The rest are extraneous (if not harmful in larger amounts) to good health.

Is this not correct?

(Chuck) #5

All I really know is that if I eat too much carb, even with protein and fat, I get hungry sooner. If I eat very little carbs, and mostly fatty proteins I never seem to get hungry. So while I don’t eat strictly low carb, I eat nothing but real carbs, no processed carbs, no fast foods, and no artificial sweeteners. I also fast an average of 19 hours each day.

(Bacon enough and time) #6

I didn’t know there was an order to all this. Alcohol is very easily absorbed by the mouth, oesophageal, and stomach linings, so it makes sense it would hit the liver before any fructose did. It is indeed known that fibre in a meal can slow the absorption of other nutrients, but it has no further effect once they do get absorbed.

We also know that too much glucose in the blood stream is an emergency, so insulin switches the body from metabolising anything else to dealing with the glucose (metabolising it in muscle cells, storing it as fat in fat cells).

I am assuming that proteins get disassembled by the acid in the stomach, though they may have to wait for the small intestine to deal with them. Fatty acids go right into the system. The liver packages them into chylomicrons for distribution–some to muscle cells for immediate energy, the rest to fat cells for use between meals (assuming insulin has not been elevated by too much carbohydrate/glucose in the blood).

But apart from tall that, and as far as I can tell, there is plenty of room for multi-tasking all these processes. Sure, the liver may have to stop producing ketones in order to give alcohol priority, but is this known for sure, or just someone’s guess? Surely the different metabolic pathways in the liver can also operate simultaneously, as well as all the processes throughout the body.

On the other hand, it is entirely possible that my brain has been addled by the painkiller I’m on, so any corrections to the foregoing will be most welcome.

(Joey) #7

Thanks for the more detailed info on the dynamics of macro processing within the body.

I have no clear recollection of just where I “learned” about this supposed order, but I wouldn’t have thought of it on my own (am not quite that creative :wink: ) so it must have been gleaned from less-than-reliable sources in recent years.

(Bacon enough and time) #8

Probably from the same place I learned about how arterycloggingsaturatedfat wants to kill us, and how a healthy breakfast consists of sugar with added grains. :scream:

(The bit about how we need five servings a day of fruit comes from the United Fruit Growers’ Association in the U.S. The need to stay “regular” was taught to us by Phillip’s Milk of Magnesia.)

(M) #9

Perhaps it’s from many things I’ve read, but I was under the impression if I ate salmon with say a lot of fatty chunks of something that the salmon would sit in my stomach longer. It seems everybody is saying that’s not the case though.

(B Creighton) #10

I’m not sure about that, but you are right that fat slows carb digestion. Eating potatoes with fat for example will slow and spread out the glucose spike from the carbs. Anyone with a CGM can confirm this. Thus, the habit of putting butter on your potato is probably a good thing. The main thing stomach acids are designed for is breaking down proteins into their amino acid components. Fats are already an acid…and are generally broken down with enzymes and absorbed in the intestines - the purpose of bile. Just by diluting the stomach acid, the fats may slow the breakdown of proteins, but other than that, I don’t believe they slow the digestive process too much, although that may depend on the individual. I digest my food generally within a 14-16 hr clock. It doesn’t seem to matter too much what I eat - it is going to come out by the 16th hour.