I needed to pause the video just to say this....IF I EVER BECOME A BIOCHEM PROFESSOR, I WILL PLAY THIS VIDEO FIRST DAY WITHIN THE FIRST 5 MINUTES AND SAY CLASS DISMISSED RIGHT AFTER...SEE YOU AT THE END OF THE SEMESTER FOR FINAL...YOU ARE AMAZING SIR!
I love the way you teach and appreciate your videos more than I can say. I'm studying for the MCAT and my undergrad education did not do a good job of connecting all of these pathways with the actual big picture and why they're important. In 30 minutes with this video and so many of your other videos, it's all coming together for me now. Thank you for the time and effort you put into helping other students learn and succeed. It is SO appreciated!
That was brilliant1 A bit of a roller-coaster ride, but we got there safely! (Just a note - I suggest that from your own discourse, you consider three states of metabolism: Fed; fasted and starvation.) Thanks though.
HOWEVER! i find your teaching skills are quiet amazing .thank you ❤.you ve been a really good help to me to figure out this 40+ pages note im having right now.❤❤🗿
First, thank you very much for your wonderful videos. It's obvious how much time you put in to organize difficult concepts into very relatable, bite-size chunks :) Second, I have a question that would be awesome if you (or anyone else) can answer: Around 30:00, you said one can live indefinitely off of our fat stores. So why can't a 500lb person stay alive without eating anything until they're skinny? Assuming they get water and vitamin pills to refill minerals/vitamins - can't they just live off the fat until they're just skin and bones? This is hypothetical, of course. But we all know they still have to eat a little regularly to stay alive, so in theory, why can't they just completely not eat and still not die??
If you have vitamins, electrolytes and essential amino acids you actually can live for extended periods of time off of your body fat.. the body and kidneys is limited in how much you can recycle cellular components but read about angus barbieri I think you’d find it very interesting!
@@sciencesimplified3890 but what about rbc's they can't use ketone bodies ? And one thing i don't understand is why can't brain and Enterocytes directly use acetyl coA to make energy through krebs cycle. Why do we need to first convert it into ketone bodies. And apart from this why even prefer gluconeogenesis when we have acetyl coA.
@@wamiqfarooq7401 Hey, so there are cells in the body that are heavily reliant on glucose (RBC etc). Therefore, Gluconeogensis is important to make sure we always have glucose in the blood. Also I’m a bit confused on the second part of your question, the liver uses glucose from our diet, converts it to ketones (a good form of energy that can be transported to other cells, and also the liver doesn’t have enzymes to use ketones so forces the liver to provide ketones to other cells). Ketones are much more portable because acetyl coa is actually a huge molecule (the coa part) and perhaps wouldn’t make a good fuel that can be transported and taken up by distant cells?
Haha sorry Ive been busy with medical school haha but my biology of aging video touches on how calorie restriction and fasting -> mTOR -> longevity and reduced incidence of chronic diseases.. although nothing is set in stone when it comes to biology haha
Great video, but I don't understand why AA degradation is categorized under the fed state at 30:30? During fasted state you discussed how proteins are degraded to supply the carbons for gluconeogenesis. Does AA degradation happen during both states?
Haha that is a great question and I’ve been very curious about protein metabolism in regards to fed fasted state... what I can tell you is it depends on the amino acid first of all... but generally speaking if you eat a huge protein diet, after a certain threshold the excess amino acids are quickly oxidized... and in a fasted state your body is catabolizing certain proteins as a source of carbons for gluconeogensis... it’s complicating tho because under certain contexts the body can be extraordinarily efficient at recycling amino acids... and when it comes to protein anabolism/catabolism it is also complex... in fed state there is some global activation of protein translation machinery, however the way you should think about it is that individual proteins are regulated individually and should not be discussed under fed and fasted state context(although that’s even more complex because under starvation there is a different set of protein catabolism pathways activated) so protein metabolism is very complex
@@tmujir955 yeah I mean that's a particular question ive been curious about for a while also but didn't know how to incorporate it (plus even what I wrote above was a simplification so its complicating) but no problem!
@@sciencesimplified3890 Hey I just wanted to say I scored in the 95th percentile and I owe a lot of that to your videos. I struggled so much with Chem and Phys but your simple explanations for complex topics really helped me get through it. Thank you so much for your efforts.
To be honest, I’m in the middle of medical school and am so busy in my course load... maybe during the summer or once I graduate but for now like I have a super busy study schedule and my biggest regret is some days I’d make like 4 videos in a single day... and instead I wish I made 1 video per 4 days and I regret sacrificing quality for quantity... so if I do post any more videos I want to make sure they’re higher quality
To be honest I have a few ideas like eventually I want to make a video on the current state of cancer research, current state of Alzheimer’s research, current state of aging research, the science of fasting, and the science of exercise. So I’ve been taking notes in all these subjects and eventually I will make those videos but for now I just need to get through medical school and residency LOL 🤣
And the last thing I want to do is to contradict the standard of care and I really hope to spread “evidence based medicine”... it is so highly irresponsible when people make videos contradicting standard of care so I want to be super careful while still offering a brief synopsis of how current researchers think about these topics
my professor said 70% of TAG is from De novo and 30% is from diet. could you elaborate on what you mean when you said that the majority of TAG comes from dietary sources?
Tbh I made this video awhile ago.. but my recollection is that it depends on many factors like diet lifestyle bmi (and depends on which tissue to a certain extent).. I’ve heard researchers argue about this to death and I think a lot of the argument stems from differences in mouse studies vs human radiolabeled isotope tracer studies.. but there are some researchers who would support what you’ve said and it’s a fair comment.. perhaps at some point I will remake this video to clarify further
If gluconeogenesis continues even after the body switches over to using ketone acids as an energy source, what happens to all that glucose? And does that mean proteins continue to be consumed unsustainably as a source of amino acids to fuel gluconeogenesis, just perhaps at a lower rate? The chart you shared near the start showed gluconeogenesis continuing almost at a constant level beyond 40 days, so I'm curious how the body sustains that, and why it's not reduced once ketogenesis takes over. Wouldn't that lead to a lot of extra available energy in the blood? What happens with it all?
You’re absolutely right indefinite gluconeogenesis is not sustainable because the energy(from TAG) and carbons(from mostly from glycerol and amino acids) needed for gluconeogenesis eventually runs out and the organism will die… a lot of new biochemistry happens during prolonged starvation that’s beyond the scope of this video, but the body will always need to do gluconeogenesis as long as its alive because there are tissues that require glucose as a source of energy (for example mature RBCs do not have mitochondria, so therefore need glucose/glycolysis to produce energy) along with other tissues that cannot use ketones as a source of energy.. and depending on which phase of starvation an organism is in but most tissues will use primarily ketones as a source of energy and other tissues will still always require glucose.. the brain is also very complex because normally glia use glucose to form lactate that feeds neurons (for certain cortex tissues).. so the truth is this is very complex biochemistry so the goal of this video was to divide metabolism into fed vs fasted state to help understand the context of metabolic pathways vs just rote memorization of pathways
@@sciencesimplified3890 that clears it up a bit, so basically GNG continues, but ketolysis takes over as the primary source of energy wherever it can? I guess where I'm still a bit lost is on that time course chart, which shows GNG pumping out ~ 9 g/h of glucose out to 40 days, but if ketogenesis is also happening within those 40 days, would that effectively raise total available energy in the blood much higher than when the body is running on GNG alone? So I'm wondering what happens to all that excess energy- does it just get dumped out as waste after building up to a certain concentration in the blood? The video was super helpful, it definitely made the processes make sense to me at a high level.
I’m pretty sure the glucose is not loss in the urine because the renal systems for glucose resorption will not be saturated at those blood glucose levels, so all the glucose filtered into the kidneys will be resorbed.. I believe at that 40 day mark, many tissues will still be able to use glucose because of basal insulin levels, plus many tissues don’t need insulin to take up glucose anyways so at that 40 day mark plenty of tissues will still be using glucose as a source of energy, but there will also be ketones created as an additional source of energy.. to be honest I don’t know the precise metrics of these dynamics so I don’t want to make any bold claims but Im pretty sure the levels of glucose made during gluconeogensis is heavily regulated so I believe the glucose that os created will be used as energy for tissues
Haha you know, the truth is it’s really hard to just memorize a bunch of random pathways... but when you create a cohesive story understanding why these pathways are occurring and understanding the big picture, then there is less you need to memorize so really it’s just understanding the big picture goal of fed state and everything you need to do for fed state, and then understanding big picture goal of fasted state, and then all the details and pathways all make sense once you create a logical cohesive story
Considering that resting skeletal muscle tends to derive its energy differently depending on whether you are in the fed or in the fasted state (Fed state: glucose; Fasted state: fatty acids), how the exercising muscle obtains its energy in these two states?
You’re absolutely right, skeletal muscle, cardiac muscle, cornea, tumor cells, stem cells, many different cells and tissues derive their energy differently which would have tremendously complicated this video so I left them out, but you’re 100% right it was just difficult to add all these nuances in this video that tried to simplify things
@@sciencesimplified3890 Yes, of course, I understand that you can't cover every kind of topic in a video and I am still really grateful to you for what you did. The question remains, however: in your opinion, what are the main fuel sources of resting/exercising muscle on a fed / fasted state? When we are in fasting, will skeletal muscle always mainly use glycogen as its main source of fuel and then use FA when these glycogen stores are depleted?
So my understanding is in fed state skeletal muscle uses glucose, and in fasted state especially prolonged fasting shifts to FFA... and also my understanding is that cardiac muscle is unique in that even during fed state it prefers lipids as a source of energy which I always thought was interesting
For anyone MCAT studying.... keep coming back to this video during your studying. It's pure GOLD
I needed to pause the video just to say this....IF I EVER BECOME A BIOCHEM PROFESSOR, I WILL PLAY THIS VIDEO FIRST DAY WITHIN THE FIRST 5 MINUTES AND SAY CLASS DISMISSED RIGHT AFTER...SEE YOU AT THE END OF THE SEMESTER FOR FINAL...YOU ARE AMAZING SIR!
I love how you consistently summarize the main points throughout the video. Thanks!
The sweet joy in internally screaming "I GET IT NOW OH MY GOD" while watching your videos is the reassurance I need for the MCAT!!! Thank you!!
I love the way you teach and appreciate your videos more than I can say. I'm studying for the MCAT and my undergrad education did not do a good job of connecting all of these pathways with the actual big picture and why they're important. In 30 minutes with this video and so many of your other videos, it's all coming together for me now. Thank you for the time and effort you put into helping other students learn and succeed. It is SO appreciated!
I love how you connected all the dots together. Thank you for sharing with us your wisdom. God bless!
This channel is gold for quick repetition of important biochemistry concepts.
Thank you.
Art, Fucking Art. Love you bro. No words. It's what happens when you are passionate.
That was brilliant1
A bit of a roller-coaster ride, but we got there safely!
(Just a note - I suggest that from your own discourse, you consider three states of metabolism:
Fed; fasted and starvation.)
Thanks though.
Excellent excellent summary! Perfect for M1 recap!
This is a piece of art! Thank you so much for the great explanation!
My test is next week, thanks a lot brotha
HOWEVER! i find your teaching skills are quiet amazing .thank you ❤.you ve been a really good help to me to figure out this 40+ pages note im having right now.❤❤🗿
Extremely well done.
Thanks Science Simplified!! Really appreciate your videos!!
Your videos are super helpful! Thank you! :)
Phenomenal video.
First, thank you very much for your wonderful videos. It's obvious how much time you put in to organize difficult concepts into very relatable, bite-size chunks :)
Second, I have a question that would be awesome if you (or anyone else) can answer: Around 30:00, you said one can live indefinitely off of our fat stores. So why can't a 500lb person stay alive without eating anything until they're skinny? Assuming they get water and vitamin pills to refill minerals/vitamins - can't they just live off the fat until they're just skin and bones? This is hypothetical, of course. But we all know they still have to eat a little regularly to stay alive, so in theory, why can't they just completely not eat and still not die??
If you have vitamins, electrolytes and essential amino acids you actually can live for extended periods of time off of your body fat.. the body and kidneys is limited in how much you can recycle cellular components but read about angus barbieri I think you’d find it very interesting!
@@sciencesimplified3890 but what about rbc's they can't use ketone bodies ?
And one thing i don't understand is why can't brain and Enterocytes directly use acetyl coA to make energy through krebs cycle. Why do we need to first convert it into ketone bodies.
And apart from this why even prefer gluconeogenesis when we have acetyl coA.
@@wamiqfarooq7401 Hey, so there are cells in the body that are heavily reliant on glucose (RBC etc). Therefore, Gluconeogensis is important to make sure we always have glucose in the blood. Also I’m a bit confused on the second part of your question, the liver uses glucose from our diet, converts it to ketones (a good form of energy that can be transported to other cells, and also the liver doesn’t have enzymes to use ketones so forces the liver to provide ketones to other cells). Ketones are much more portable because acetyl coa is actually a huge molecule (the coa part) and perhaps wouldn’t make a good fuel that can be transported and taken up by distant cells?
Thank you so much ❤ it's clear now. Sending good vibes. You are doing great work.
Is there a link to the video on the benefits of fasting that discusses the DNA repair and healing processes?
Haha sorry Ive been busy with medical school haha but my biology of aging video touches on how calorie restriction and fasting -> mTOR -> longevity and reduced incidence of chronic diseases.. although nothing is set in stone when it comes to biology haha
Very helpful video, thank you!
Thank you so much
What happened to the next video where you explain the benefits of fasting?
thank you so much man
God bless you my love ❤️❤️❤️
there is a special place for you in heaven.
Yep, that's good
Great video, but I don't understand why AA degradation is categorized under the fed state at 30:30? During fasted state you discussed how proteins are degraded to supply the carbons for gluconeogenesis. Does AA degradation happen during both states?
Haha that is a great question and I’ve been very curious about protein metabolism in regards to fed fasted state... what I can tell you is it depends on the amino acid first of all... but generally speaking if you eat a huge protein diet, after a certain threshold the excess amino acids are quickly oxidized... and in a fasted state your body is catabolizing certain proteins as a source of carbons for gluconeogensis... it’s complicating tho because under certain contexts the body can be extraordinarily efficient at recycling amino acids... and when it comes to protein anabolism/catabolism it is also complex... in fed state there is some global activation of protein translation machinery, however the way you should think about it is that individual proteins are regulated individually and should not be discussed under fed and fasted state context(although that’s even more complex because under starvation there is a different set of protein catabolism pathways activated) so protein metabolism is very complex
Thank you for your reply, and even more for the videos!
@@tmujir955 yeah I mean that's a particular question ive been curious about for a while also but didn't know how to incorporate it (plus even what I wrote above was a simplification so its complicating) but no problem!
Good question.
@@sciencesimplified3890 Hey I just wanted to say I scored in the 95th percentile and I owe a lot of that to your videos. I struggled so much with Chem and Phys but your simple explanations for complex topics really helped me get through it. Thank you so much for your efforts.
Hi! I cant find the benefits of fasting video.... What is the title specifically?
love your videos btw
To be honest, I’m in the middle of medical school and am so busy in my course load... maybe during the summer or once I graduate but for now like I have a super busy study schedule and my biggest regret is some days I’d make like 4 videos in a single day... and instead I wish I made 1 video per 4 days and I regret sacrificing quality for quantity... so if I do post any more videos I want to make sure they’re higher quality
@@sciencesimplified3890 No worries!!!! good luck in med school!
To be honest I have a few ideas like eventually I want to make a video on the current state of cancer research, current state of Alzheimer’s research, current state of aging research, the science of fasting, and the science of exercise. So I’ve been taking notes in all these subjects and eventually I will make those videos but for now I just need to get through medical school and residency LOL 🤣
And the last thing I want to do is to contradict the standard of care and I really hope to spread “evidence based medicine”... it is so highly irresponsible when people make videos contradicting standard of care so I want to be super careful while still offering a brief synopsis of how current researchers think about these topics
Why is amino acid degredation in the fed state at the end of the video?
my professor said 70% of TAG is from De novo and 30% is from diet. could you elaborate on what you mean when you said that the majority of TAG comes from dietary sources?
Tbh I made this video awhile ago.. but my recollection is that it depends on many factors like diet lifestyle bmi (and depends on which tissue to a certain extent).. I’ve heard researchers argue about this to death and I think a lot of the argument stems from differences in mouse studies vs human radiolabeled isotope tracer studies.. but there are some researchers who would support what you’ve said and it’s a fair comment.. perhaps at some point I will remake this video to clarify further
@@sciencesimplified3890 interesting. Thanks for the reply
If gluconeogenesis continues even after the body switches over to using ketone acids as an energy source, what happens to all that glucose? And does that mean proteins continue to be consumed unsustainably as a source of amino acids to fuel gluconeogenesis, just perhaps at a lower rate? The chart you shared near the start showed gluconeogenesis continuing almost at a constant level beyond 40 days, so I'm curious how the body sustains that, and why it's not reduced once ketogenesis takes over. Wouldn't that lead to a lot of extra available energy in the blood? What happens with it all?
You’re absolutely right indefinite gluconeogenesis is not sustainable because the energy(from TAG) and carbons(from mostly from glycerol and amino acids) needed for gluconeogenesis eventually runs out and the organism will die… a lot of new biochemistry happens during prolonged starvation that’s beyond the scope of this video, but the body will always need to do gluconeogenesis as long as its alive because there are tissues that require glucose as a source of energy (for example mature RBCs do not have mitochondria, so therefore need glucose/glycolysis to produce energy) along with other tissues that cannot use ketones as a source of energy.. and depending on which phase of starvation an organism is in but most tissues will use primarily ketones as a source of energy and other tissues will still always require glucose.. the brain is also very complex because normally glia use glucose to form lactate that feeds neurons (for certain cortex tissues).. so the truth is this is very complex biochemistry so the goal of this video was to divide metabolism into fed vs fasted state to help understand the context of metabolic pathways vs just rote memorization of pathways
@@sciencesimplified3890 that clears it up a bit, so basically GNG continues, but ketolysis takes over as the primary source of energy wherever it can? I guess where I'm still a bit lost is on that time course chart, which shows GNG pumping out ~ 9 g/h of glucose out to 40 days, but if ketogenesis is also happening within those 40 days, would that effectively raise total available energy in the blood much higher than when the body is running on GNG alone? So I'm wondering what happens to all that excess energy- does it just get dumped out as waste after building up to a certain concentration in the blood?
The video was super helpful, it definitely made the processes make sense to me at a high level.
I’m pretty sure the glucose is not loss in the urine because the renal systems for glucose resorption will not be saturated at those blood glucose levels, so all the glucose filtered into the kidneys will be resorbed.. I believe at that 40 day mark, many tissues will still be able to use glucose because of basal insulin levels, plus many tissues don’t need insulin to take up glucose anyways so at that 40 day mark plenty of tissues will still be using glucose as a source of energy, but there will also be ketones created as an additional source of energy.. to be honest I don’t know the precise metrics of these dynamics so I don’t want to make any bold claims but Im pretty sure the levels of glucose made during gluconeogensis is heavily regulated so I believe the glucose that os created will be used as energy for tissues
Great ....thank you
Thank you very much! You save my ass!
crazy how u know all this from the top of your head
Haha you know, the truth is it’s really hard to just memorize a bunch of random pathways... but when you create a cohesive story understanding why these pathways are occurring and understanding the big picture, then there is less you need to memorize so really it’s just understanding the big picture goal of fed state and everything you need to do for fed state, and then understanding big picture goal of fasted state, and then all the details and pathways all make sense once you create a logical cohesive story
Considering that resting skeletal muscle tends to derive its energy differently depending on whether you are in the fed or in the fasted state (Fed state: glucose; Fasted state: fatty acids), how the exercising muscle obtains its energy in these two states?
You’re absolutely right, skeletal muscle, cardiac muscle, cornea, tumor cells, stem cells, many different cells and tissues derive their energy differently which would have tremendously complicated this video so I left them out, but you’re 100% right it was just difficult to add all these nuances in this video that tried to simplify things
@@sciencesimplified3890 Yes, of course, I understand that you can't cover every kind of topic in a video and I am still really grateful to you for what you did. The question remains, however: in your opinion, what are the main fuel sources of resting/exercising muscle on a fed / fasted state? When we are in fasting, will skeletal muscle always mainly use glycogen as its main source of fuel and then use FA when these glycogen stores are depleted?
So my understanding is in fed state skeletal muscle uses glucose, and in fasted state especially prolonged fasting shifts to FFA... and also my understanding is that cardiac muscle is unique in that even during fed state it prefers lipids as a source of energy which I always thought was interesting
Benefits of fasting video 📼? What’s the title?
😅
"HOWEVER" @ScienceSimplified