I have the Quixotic goal to put on some more lean muscle (not easy or fast when one is in their 50’s). To this end, I try to eat a high-protein diet, as that is required to form new muscle tissue. I was thinking - if one eats more fat that the body needs, it ends up being stored. Carbs get turned into fat and stored, too. What about protein? Is that stored, or is any excess just wasted? Also, how is it distributed to where it is needed (clearly, in the bloodstream, but in what form)?
In a high protein diet, most of the protein will probably be burned for energy anyway. The nitrogenous part is excreted in the urine. Any excess over the body’s energy requirements will be turned into fat just like the excess calories from fat and carbohydrates.
njtt is mostly correct save that in the case of having substantial excess protein much of it just gets excreted and doesn’t generally contribute significantly to the effective caloric load, which also stresses the kidneys. In the case of fat, complex facts (such as triglycerides) don’t convert directly to adipose tissue but instead break down into glycerols and fatty acids. The glycerols can be stored as adipose tissue, but the fatty acids convert to glucose via gluconeogenesis or are excreted. The only time protein is used as a major energy source is when the body is in starvation mode and will start consuming structural proteins (i.e. muscle, tendons, ligaments) to synthesize glucose. The body only stores protein in these structures and nowhere else in significant quantity. (This is not strictly true; adipose tissue also has proteins, of course, but it comes with an increase in body fat that is undesireable.)
However, the body is extremely efficient about reusing protein, so if you are just trying to maintain muscle mass you don’t need a really high protein intake (unless you are hypertropied to an unsustainable level). If you want to gain lean muscle mass, however, you must increase your protein intake as well as increasing carbohydrate and fat intake to propotional levels to support structural development of muscles.
Stranger
Furthermore, you don’t really need so much protein in your diet; what you need is amino acids. Proteins get broken down into amino acids anyway; your body then synthesizes all-new proteins that it needs, de novo, from those.
Amino acids can come from vegetables as well as meats (yes, typically as proteins). But in choosing your diet, pay attention to what amino acids various foods can supply.
This is the nutritional basis of the traditional Mexican diet of rice and beans: Neither supplies all the amino acids you need in their proteins, but the combination of rice and beans does.
There are amino-rich foods where the amino acids aren’t bound in proteins? If not, why make the distinction?
njtt supplies the basic answer. Excess carbohydrate can be stored to some significant degree as glycogen (and beyond that the energy and parts from it stored as fat), excess fat can be stored, but we have no real capacity to store excess amino acids, other than muscle being net gained. That said if you want to get into the weeds so to speak it it is a bit more complex.
This article may be a bit esoteric to wade through but might be of interest.
Ingested protein is broken down into its component amino acids and absorbed. The elevated serum amino acids (in particular certain essential amino acids, meaning ones the body cannot produce itself) are part of what drives a rise in insulin (synergistically with carbs) and both the elevated serum amino acid level directly and the elevated insulin level (and other hormone responses as well) then impact the body protein balance.
Balance is a key word here. There is a balance between body proteins being broken down (catabolism or proteolysis) and proteins being built (anabolism or synthesis).
Muscle is not the sole substance of protein in the body; enzymes are made of protein, many transmitters and hormones, hair, etc. … But those are pretty much steady state and smaller amounts, in terms of variation in rate of catabolism and synthesis muscle is the big player.
The process of getting the amino acids into serum, elevating the level, elevating insulin, and impacting that balance, varies with different protein sources. Whey causes a brief spike, higher and shorter, while casein’s peak was lower and more prolonged. Whey and had a major impact on protein synthesis and fairly little decrease on proteolysis (breakdown). Casein OTOH had a more mild impact on protein synthesis but substantially decreased the rate of proteolysis for hours later. On net the slow digestion resulted in more protein retention.
Of course this was in young adults and not taking into account timing of exercise. The conclusion of that article noted that what happens in the young is definitely not the same as what happens to us as we age.
So here’s another article!
So bottom line - more protein over a 24 hour period above and beyond something like 25% of your daily calories is not going to do much for you. You won’t store it. Probably divvying it up something like 20 grams of whey right after resistance exercise (to maximally stimulate synthesis), followed by some slower to absorb protein like casein a bit later (to inhibit proteolysis) along with regular healthy meals, is the best tactic to maximizing your net gain.
I thought it was corn and beans that made the complete protein. The rice, unless it’s unrefined, can’t do that.
Jesus Christ, please read some basic information on nutritional biochemistry before repeating baldly uninformed factoids from random internet sources.
Yes, you can get complete proteins (e.g. those that include the nine essential amino acids required for human nutrition) from vegetable sources. And in general, you get some proportion of all twenty-two ‘standard’ amino acids from dietary sources. Getting a sufficient quantity in the correct proportion can be tricky and requires an extensive understanding of nutritional balance. In general, amino acids are reduced from proteins by proteases such as trypsin and pepsin rather than being consumed in ‘simple’ form, mostly because people prefer to eat steak and chicken rather than nasty reeking slurries of protein precursors.
All of the structural elements of both plants and animals are formed by proteins, or (in the case of skeletal material) the deposits of proteins that have since been recycled.
The body has no mechanism for ‘storing’ protein other than by creating muscles or other structures, period. There is a small amount of protein in the circulation system at any given time, and proteins will be recycled and recovered by tissue that isn’t being regularly exercised, but there isn’t any reservoir for storing protein for some later purpose. Hence, the necessity of ensuring an adequate protein load before or after strengthening exercise.
Stranger
Stranger it really is not so tricky to get adequate high quality protein from vegetable sources.
Rice is low in lysine and fine in others including methionine. As is corn. And wheat based pasta and tortillas. OTOH yourtypical legume is fine on lysine and low on methionine. So having some legumes and some grains in a day will usually suffice. Tofu and quinoa are complete by themselves. So is chia. The other essential amino acids than lysine and methionine are pretty hard not to get in any protein source, so a vegan only needs to make sure to have some reasonable amount of by itself complete protein or match up some grain/seed (corn, rice, wheat, etc.) with some legumes over the course of the day. No PhD in nutrition required.
And protein from many sources will result in elevation in serum amino acid levels for many hours, see the data on casein above. More than what is a small amount to most people’s minds.
If you are going to blast other posters please be sure you are not spouting off uninformed factoids yourself.