Fresh vs. Frozen (vs. Canned) Produce, Who Wins? Part 2: Frozen

Welcome back! We’re continuing our discussion on whether you should eat fresh, frozen, or canned fruits/veggies. So far, we’ve seen the pros and cons of fresh produce: High in nutrient density, but loses its nutrients quickly if stored for a few days! How can we combat that?? Hmmm…..??? Got it! Freeze the colorful bastards! Yes! I’m saying freeze your produce or buy frozen if you know you store food for a while. Also, you may get more nutrients from doing this. Let’s look at what the data says about frozen produce in comparison to other methods!

Frozen Produce


Last post, I did not include processing as a means of loss because fresh fruits/veggies don’t really experience much processing that could affect nutrient availability. Time was a primary factor in losses from fresh produce. I include it here because the freezing process can have an effect on the nutrients in food.

Processing for produce involves cooking the food then quickly freezing it. This is typically accomplished through blanching. This process involves boiling the food for a very short period of time, enough to cook it. Then, the food is thrown in cold water or an ice bath to freeze! This process can yield some losses in nutrients.

For example, one study found a 63% loss of Vitamin C in green peas just from freezing the food1. Numerous studies were compared to examine the loss of Vitamin C during the blanching and freezing process. Across the board, there was a lot of variance (From 17%-63% losses). Alternatively, while broccoli and spinach showed the greatest losses, asparagus appeared to be the hardiest vegetable, as Vitamin C was shown to retain 90% of its concentration after freezing2. Most of the vegetables reviewed saw fewer losses of ascorbic acid to freezing than canning, with some veggies losing as much as 90% of their Vitamin C just from the canning process2.

Losses of B-vitamins are similar to Vitamin C in that they vary greatly between studies, but the percentages were, on average, lower in terms of percent lost to freezing. Freezing was similarly a more efficient process than canning to preserve B-vitamins2.

For the fat-soluble Vitamin A (specifically beta-carotene), their does not appear to be a major change in loss between canning and freezing; they both appear to lose about the same amount2. Vitamin A was shown, as seen through multiple studies, to have losses ranging from 5%-48%2. The authors of the review made an interesting point that the typical American’s main source of Vitamin A is through lycopene in tomatoes, and these are not normally frozen2, so this may not be a super important point if most of our intake is from tomatoes anyway!

Not much is mentioned of Vitamin E, but it appears that canning may produce a slightly greater amount of the vitamin than fresh and frozen counterparts2.

In terms of minerals, fresh, frozen, and canned veggies all were neck-and-neck. One food would have more calcium when canned, then the next would have more calcium when fresh, and so on and so on. Just from my judgement, with the exception of sodium, it seemed as though fresh and frozen produce showed, on average, higher amounts of the minerals when compared to canned counterparts3.

For fiber and processing, the only time fiber was lost was when some of the fibrous portions of the food were physically removed. There appears to be nothing about canning or freezing the affects fiber if the food is left intact2.


As one can imagine, frozen produce does much better than fresh in terms of nutrient retention during storage. Regarding Vitamin C, after one year of storage, one study saw an average decrease of 20%-50% for food such as broccoli and spinach4 whereas fresh foods can see those losses or greater in as little as 24 hours5!

Unfortunately, the data is pretty inconclusive about B-vitamin losses, so I’m not going to include it here.

In regards to Vitamin A, some studies say a small increase in Vitamin A concentration after storage6 while others saw no change or decreases after storage for a period of time7.

Data from the USDA suggest that some foods like tomatoes and sweet potatoes contain higher levels of Vitamin E when canned compared to their fresh and frozen equivalents; however, spinach and asparagus showed higher levels when fresh or frozen8. Basically, the results are inconclusive, there is no clear winner for this category.

As mentioned in the last post, fiber and minerals are much hardier components of food than the other vitamins, so losses from them are very minimal, including when they are frozen for months on end8.


Home-cooking foods can have a significant effect on nutrient losses. Generally, when heat is applied, some losses will occur, especially in the water-soluble vitamins.

When compared with canned and fresh produce, frozen held its own with fresh foods for Vitamin C retention-throughout processing, storage, and canning-being very similar in nutrient quality compared across a range of foods. Canned produce fell short, withstanding significant losses throughout the processing, storage and cooking steps2.

For the B-vitamins, it has been seen that Thiamin, a vitamin important for cell metabolism and growth9, can witness small or significant losses during the cooking process (11%-66% loss of nutrient)10. From other studies, they showed that canned and frozen produce fell equally short to fresh foods after cooking for the B-vitamins11,12.

Vitamin A one again saw increases in availability after cooking. Some of the foods saw even greater percent changes when frozen than when cooked. For example, one study saw only a 5% increase in Vitamin A for carrots when fresh compared to a 21% increase when frozen13

Vitamin E in frozen foods was not really mentioned, so I will skip this portion.

When looking at the minerals sodium, calcium, and potassium, some interesting results were noticed. Across the board, concentrations of potassium and calcium were similar after cooking for fresh, frozen, and canned foods when testing green beans and peas12. One can assume that canned foods will have a higher amount of sodium due to processing12. What this tells us is that generally, produce will have similar amounts of the beneficial minerals. If you’re watching sodium, opt for either non-canned options or those that are sodium-free/no salt added. One caveat, this study only looked at those two vegetables. The results may be different when looking at fruits and vegetables. My personal opinion is that it may not be too different simply because minerals are more resistant to heat and cooking than the vitamins.

In reference to the last post, fiber isn’t really lost from the cooking process unless you physically remove the tough, fibrous, parts of food. Researchers went to the grocery store and purchased some food off the shelf to observe its fiber content and compare fresh, frozen, and canned foods. What they found was that cooked frozen and cooked canned green beans and peas had 25%-35% greater amounts of fiber than the cooked fresh counterpart12.

Keep in mind, this is one grocery trip they took. Fiber content may vary between batches, but it is an interesting point because I think that most people would think that the fresh food will always have more nutrients, which, as we just saw, is not always the case.

Phew, this was a longer post than most of the others. My b. But there was a lot to cover! I will be going over specifically canned produce next week, so look forward to that! Here are my takeaways!


  • Frozen foods last significantly longer than fresh foods. If you plan on having food for a long time or like to stockpile for nuclear war for some weird reason, go frozen.
    • In many cases, frozen foods have similar nutrient amounts to fresh.
  • In addition, frozen foods take a long time on average to lose a lot of their nutrients, so store those babies for a while, you’ll be good!
  • Frozen foods (including meals) are a quick and easy way to make a meal, since the prep work is usually done.
  • Try limiting the time you heat/cook any kind of produce. The longer it stays in hear or water, the greater chance you will lose nutrients
    • On the other hand, don’t drive yourself nuts and only eat raw foods, that’s not the way either. If you can limit water and heat use and still get the same product, great. If not, no biggie, enjoy your damn food.


I hope you found this article useful. Let me know how use frozen foods in your meals/meal planning, I’m always looking for ideas!


1Fellers CR and Stepat WEffect of shipping, freezing and canning on the ascorbic acid (vitamin C) content of peasProc Am Soc Hort Sci 32627633(1935).

2Rickman, J., Barrett, D., & Bruhn, C. (2007). Nutritional comparison of fresh, frozen and canned fruits and vegetables. Part 1. Vitamins C and B and phenolic compounds. Journal of the Science of Food and Agriculture, 87(6), 930-944.

3Makhlouf JZee JTremblay NBelanger AMichaud MH and Gosselin ASome nutritional characteristics of beans, sweet corn and peas (raw, canned and frozen) produced in the province of QuebecFood Res Int 28253259 (1995)

4Hunter KJ and Fletcher JMThe antioxidant activity and composition of fresh, frozen, jarred and canned vegetablesInnov Food Sci Emerg Technol 3399406(2002).

5Favell DJA comparison of the vitamin C content of fresh and frozen vegetablesFood Chem 625964 (1998).

6Salunkhe DKBolin HR and Reddy NRChemical composition and nutritional quality, in Storage, Processing, and Nutritional Quality of Fruits and Vegetables. Vol. 2: Processed Fruits and Vegetables. CRC Press, Boca Raton, FL, pp. 115145 (1991).

7Elkins ERNutrient content of raw and canned green beans, peaches, and sweet potatoesFood Technol 336670 (1979).

8Rickman, J., Bruhn, C., & Barrett, D. (2007). Nutritional comparison of fresh, frozen, and canned fruits and vegetables II. Vitamin A and carotenoids, vitamin E, minerals and fiber. Journal of the Science of Food and Agriculture, 87(7), 1185-1196.

9Thiamin Fact Sheet From NIH

10Rumm-Kreuter D and Demmel IComparison of vitamin losses in vegetables due to various cooking methodsJ Nutr Sci Vitaminol 36S7S15(1990).

11Lisiewska ZKorus A and Kmiecik WChanges in the level of vitamin C, beta-carotene, thiamine, and riboflavin during preservation of immature grass pea (Lathyrus sativus L.) seedsEur Food Res Technol 215216220(2002).

12Wills RBEvans TJLim JSScriven FM and Greenfield HComposition of Australian foods. 25. Peas and beansFood Technol Aust 36512514 (1984).

13Howard LAWong ADPerry AK and Klein BPβ-Carotene and ascorbic acid retention in fresh and processed vegetablesJ Food Sci 64929936(1999).


Fresh vs. Frozen (vs. Canned) Produce, Who Wins? Part 1: Fresh

People are always going to argue over the stuff that is 5% of the equation while ignoring the actually important 95%. This debate between fresh, frozen, and canned produce is part of that 5%. Why? Because for the most part, a vegetable is a vegetable is a vegetable. While we may want to get all of our nutrition from fresh foods and be #healthy, that’s not always financially, practically, or geographically possible. Luckily, with the technological advancements in food processing (yes, I think processing can be a good thing), we are able to preserve foods and acquire foods we would never have gotten a chance to eat given our location. These developments have not come without criticism, however.

Many will claim that canned or frozen fruits and vegetables are not “as healthy” as their fresh counterpart. First off, please define healthy. You can’t measure something with healthy. “Oh, this food has 5 health”, this isn’t a freaking video game. Talk about nutrient density; that’s a good way to measure the healthfulness of a food. Nutrient density refers to the quantity and variety of nutrients (vitamins, minerals, fiber content, etc.) that are in a food. Obviously, fruits and veggies are extremely nutrient dense; but do they contain the same amount and types of nutrients across the board from fresh to frozen to canned? That’s the topic of discussion for today.

The Research

In 2007, there was a great literature review published in the Journal of the Science of Food and Agriculture that compiled a lot of the research conducted in this area over the last several decades from UC Davis1. This review was broken up into 2 main sections: Water-soluble & lipid-soluble. The difference here is that some nutrients dissolve in water while others dissolve in lipids (or fats). The properties of these nutrients change depending on their solubility. For example, water-soluble vitamins (C & B) are very susceptible to destruction from high temperatures while lipid-soluble vitamins (A, D, E, K) can tolerant high temperatures and still remain in food.

Fresh Produce


While it may come as no surprise that fresh produce was shown to have greater amounts of nutrients than frozen or canned, it may be interesting to know that fresh vegetables also degrade the quickest in terms of nutrient availability2. In one study, researchers found 56-100% decreases in Vitamin C content depending on the food item being tested. This was after storing the food at room temperature for 7 days3. Keep in mind, Vitamin C is a very unstable nutrient, so it’s sensitive and will be degraded the quickest of any nutrient, but for water-soluble vitamins, it’s a good estimation. Vitamin B losses were also found during storage, but not as dramatic as Vitamin C1.

Lipid-soluble vitamins had a different story. Vitamin A, in some cases, actually saw an increase in availability after a few days. This was seen in carrots refrigerated after 14 days4. Simultaneously, green beans experienced a small 10% decrease during refrigeration from 16 days4.

In part 2 of the review, minerals and fiber were tested in addition to lipid-soluble vitamins. What was seen there was that neither minerals or fiber saw significant losses during storage over many months1, although I wouldn’t eat anything considered fresh produce after a couple months…yikes.


As mentioned previously, water-soluble vitamins can be quickly destroyed if exposed to heat such as from cooking while lipid-soluble vitamins are more tolerant of supa hot fiya. One study tested the Vitamin C content of produce straight from the supermarket after cooking and found that some foods had higher Vit. C levels when fresh and cooked while others had more of the vitamin when coming from a can and then cooked3! In addition, ascorbic acid (Vitamin C) has been shown to see decreases after cooking as high as 55%5.

Thiamin, a B-Vitamin, has seen even greater losses from cooking at 66%6. The cooking method will also be significant factor for how much of the nutrient is lost to cooking; unfortunately, the authors did not specify which methods are better than others for nutrient retention, but my guess would have to be whichever method utilizes heat for the least amount of time would be best.

Lipid soluble Vitamin A had an interesting outcome when exposed to heat; it increased! One study found a 26% increase in the amount of Vitamin A available after cooking fresh broccoli7. Other studies did not find any increase but rather, a decrease1.

Minerals and their quantity in foods are able to be reduced from cooking by leaching into the water or cooking liquid out of the food1. If possible, use that cooking liquid again to get some of that nutrient back into a meal.

Fiber did not see any significant changes when exposed to heat1. The primary way that you’re going to lose fiber from cooking is through processes like peeling, juicing, and removing parts of fruits and vegetables1. For example, asparagus spears have the signature flower part to them and the annoying tough end to them. The reason why that end is tough is because it is loaded with cellulose/fiber. I’m not saying you need to eat all the hard parts of fruits and veggies, but save a little bit of it next time to get a little extra bit of fiber from your meal.


So far, we have only covered what the research has said about fresh fruits and vegetables, and haven’t really made a comparison with frozen and canned veggies. That will come next week when we talk about frozen produce and then the following week with canned products. For now, my takeaways are this:

  • Fresh is not always the best option especially if the produce is going to sit for a couple of days.
  • If possible, place fresh items in the fridge to slow the process of nutrient degradation
  • Cooking can contribute to the greatest loss of nutrients, but don’t eat everything raw either. My point is focus more so on getting fruits and vegetables in the first place. Then, worry about cooking methods and other things.

I hope you found this information useful to you. As I said above, We’ll start actually comparing the three forms next week, then you may be able to make better decisions about what you select at the grocery store! Leave me your comments with your thoughts!


1Rickman, J., Barrett, D., & Bruhn, C. (2007). Nutritional comparison of fresh, frozen and canned fruits and vegetables. Part 1. Vitamins C and B and phenolic compounds. Journal of the Science of Food and Agriculture, 87(6), 930-944.

2Favell DJ, A comparison of the vitamin C content of fresh and frozen vegetables. Food Chem 62:59–64 (1998).

3Hunter KJ and Fletcher JMThe antioxidant activity and composition of fresh, frozen, jarred and canned vegetablesInnov Food Sci Emerg Technol 3399406(2002).

4Howard LAWong ADPerry AK and Klein BPβ-Carotene and ascorbic acid retention in fresh and processed vegetablesJ Food Sci 64929936(1999).

5Goyal RKNutritive value of fruits, vegetables, and their products, in Postharvest Technology of Fruits and Vegetables, ed. by VermaLR and JoshiVK. Indus Publishing, New Delhi, pp. 337389 (2000).

6Rumm-Kreuter D and Demmel IComparison of vitamin losses in vegetables due to various cooking methodsJ Nutr Sci Vitaminol 36S7S15(1990).

7Lessin WJCatigani GL and Schwartz SJQuantification of cistrans isomers of provitamin A carotenoids in fresh and processed fruits and vegetablesJ Agric Food Chem 4537283732 (1997).

Basic Nutrition To Fuel Your Not-So-Basic Life Part 4: Fiber

Let me tell you something about fiber. When I first began my study of nutrition about 2 1/2 years ago, my very first nutrition professor was a fiber nerd! She loved fiber and talked to us about it like it was the best thing since sliced (whole grain) bread. Over time, I’ve realized why she was so passionate about this special type of carbohydrate.

It truly is awesome because it plays host to many benefits for our health; they’re vast and highly effective for our body’s proper functioning, so I wanted to take this time to define fiber, talk about why it’s so awesome, and provide some recommendations on how much should be consumed daily.

wtF is Fiber?

Hah. Get it?

Anyway, fiber, as mentioned above and in one of my original posts on my website about carbs, fiber is a type of carbohydrate. But, it’s very special. One reason is because fiber cannot be fully digested. Our bodies do not possess the proper enzymes and digestion systems to fully break it down. Why is it so hard for the body to break down? There’s a few reasons for that.

Fiber, on a very small-scale level is made up of A LOT of sugar molecules. Collectively, these bundles of sugar molecules bonded together are known as polysaccharides. Specifically, fiber is derived from cellulose¹. You may have heard of cellulose as being the cell walls of plant cells. FUN FACT.

Think of a long chain of beads like the picture below.pexels-photo-221550.jpegImagine that each bead represents one molecule of sugar. Now, imagine that this necklace is a chain of at least 1000 beads. That is fiber. Crazy, right? Our body will get fiber from food and there are a few interesting things that happen when we consume fibrous foods.

Function of Fiber

Primarily, our blood sugar begins to level off. When looking at graphs depicting levels of glucose in the blood, we’ll often see a huge spike in blood sugar levels when we eat sugary foods and things containing simple carbohydrates. Keep in mind simple carbs refer to small chains or single units of sugar that the body can quickly break apart and utilize for energy.

With fiber, we don’t see that spike. What we see is a gradual increase in blood sugar and a peak that doesn’t typically get as high as the peak would be from simple carbs. Additionally, blood sugar levels taper down at a slower rate than simple carb spikes. This has a lot of interesting health implications and is the fundamental idea behind diabetes and insulin resistance. I won’t go into how we develop Type 2 Diabetes in this post. I’ll probably talk about Diabeetus another time.

The slow and steady increase and decrease results from the body’s inability to digest fiber. Since we can’t break down fiber completely, it will sit in the gut and become “food” for our gut’s microbiome, a “community” of microorganisms that live inside us. While we don’t have the digestive system to break down fiber, the organisms living in our gut do to some extent. So they will partially break down fibers and convert them into fatty acids that we can break down and use for energy in a process called fermentation. This process takes some time, and we get fatty acids out of it, which take a while to break down in their selves, so this is what leads to that progressive increase and decrease in blood sugar. Pretty cool, right??

This is important for our health because small and slow increases in blood sugar are easier on our pancreas. Our pancreas secretes the hormone insulin that allows sugars to be shuttled into cells for energy. Slower and steadier increases mean less insulin has to be produced and secreted at any given time. Long-term production of insulin for large spikes is a risk factor for diabetes. For this reason, fiber has been noted as a component of the diet that can reduce the risk of Type 2 Diabetes².

Additionally, fiber can help lower your cholesterol and and risk for heart disease². The way this works is that as fiber travels through your digestive system, it will bind to cholesterols that are floating around in the blood, and, since fiber can’t be digested, it will be excreted with some cholesterol still bound to it. The cholesterol that is removed is the LDL or “bad” cholesterol. In effect, this excretion of LDL lowers our blood pressure and risk of heart-related diseases²! I think that’s cool. Maybe just me.

On a side note, fiber also keeps you fuller for a longer period of time than other carbohydrates. When consumed, fiber will slow the rate of digestion for the entire meal, keeping food in your stomach and fighting hunger for a longer period of time. So, if you know that you’re going to be out for a awhile, having a meal high in fiber can ensure that you will be full and energized throughout the day!

Sources of Fiber

But where do we get foods high in fiber? Glad you asked. It’s the typical “healthy” foods. I know, booooo; but, fruits, vegetables, legumes (think beans and peas), and whole grains are the most common sources. Ever have some fruit, then get a sense of fullness afterwards? Happens to me with bananas. That’s the fiber bruh!

Fruits/vegetables are the hallmark of any healthy balanced diet, and fiber is one reason why. Most fruits/veggies will have a fair amount of fiber per serving. Simply check the nutrition facts panel to see how much!

Legumes are things like beans, peas, lentils, etc. They’re often packed with fiber AND protein.  Double whammy!

When I mention “whole grains”, I’m talking about oatmeal, quinoa, brown rice, and whole grain products (bread, pastas, tortillas, etc.). For the last set of products, make sure the package says “whole grain” or “whole wheat” somewhere or on the ingredients label to ensure you’re getting the most fiber possible.


The American Dietetic Association is very credible source (obviously), and they recommend the following for individuals². You can find the source of this chart on the 2nd reference I have listed:


Of course, you’re not going to die if you don’t hit that fiber number, but it is a good idea to actively aim for around that number listed for your age group. Having a fruit/vegetable at every meal is an easy way to start that. Or just include one more veggie than you’re already having. Small steps is the way to big successes!

Last thing, MORE IS NOT BETTER. Jumping your fiber intake rapidly or getting too much fiber may make you constipated and/or cause a lot of wind-breaking (toots, farting, passing gas, pick your favorite). As you increase your intake, make sure you’re drinking more water too in order for the digestive system to continue moving. Too much fiber can back you up if water isn’t in check. Happy eating!


  • Fiber is a type of carbohydrate that can’t be broken down in the body completely
  • Fiber has a lot of health benefits including lowering blood pressure and blood sugar²
  • Sources of fiber are the typical healthy foods like fruits, veggies, whole grains, and legumes
  • An adequate intake of fiber varies with age and sex, refer to the chart to see where you stack up!

Have questions?? Comment below about them or tell me your favorite ways to get fiber in your diet! Thanks of reading!


¹Dietary Polysaccharides (Article from Colorado State University)

²Position of the Academy of Nutrition and Dietetics: Health Implications of Dietary Fiber


I Made Some Mistakes On My Last Post, So I Fixed Them Here.

Hey y’all. Finals are done. Classes are out for a little while. I feel good. So good that I’ll be able to get back to writing every week!

Upon reading my last post about aerobic glycolysis, I noticed some issues with the article. There were some things that I either glossed over or need to revise, so this post serves as clarification on some of the hiccups in my last post. Nobody is perfect! Let’s wrap this ish’ up.

First off, I’d like to make the point clear that when you are training, energy systems don’t work like an on/off switch. For example, when you begin high intensity exercise, aerobic glycolysis is working along with the creatine phosphate and lactic acid systems. The difference is that most of your energy is obtained from the latter systems over the former at the beginning of your exercise/work that you’re doing; so energy acquired from aerobic systems will come into play later on as the length of exercise progresses, but the process has begun once you start training.

Next, I made a mistake regarding my explanation of aerobic glycolysis. Glycolysis is only part of the pie known as “Oxidative phosphorylation“. Specifically glycolysis refers to the breakdown of glucose for energy. As a reminder, we can get glucose from carbs or gluconeogenesis such as from lactate and glycerol from fats. This system (oxidative phosphorylation) is the sum of all aerobic reactions and pathways that create ATP; part of which being aerobic glycolysis. Proteins can also be used to produce small bits of ATP.

So during OP, energy may be derived from carbs, protein, and fats! Depending on the availability of nutrients will determine what your body goes for primarily. If you’re full of glucose or glycogen, then your body is going to use that because it’s the quickest and “costs” the least amount of energy to get energy. Your metabolism wants to save all the energy that it can for when it really matters.  Once glycogen stores are depleted, then fats and even proteins will take up a larger role.

Keep in mind that this system takes awhile to produce any energy, so it is not as though you can expect to lose weight just from depleting glycogen stores and relying on fat. You’ll eventually crash because the energy demand just for breathing and moving around could be greater than what can be produced. Simply, get off yo’ butt and move!

So it is a bit more complicated than just carbs and other things being converted into glucose then some magic happens and you have energy. But, that’s the exciting thing about learning! You can learn something new every day!

I hope this clarification of things helped the incomplete picture I painted previously. Maybe I just made it even more complicated. Either way, thanks for reading! Share this article and others to educate someone you know!


How Do We Acquire and Use Energy From Food? Part 2

Welcome back to our discussion of energy systems! I appreciate you coming back and your desire to learn! That’s the whole goal of this website: to learn ya’ somethin’! Upon reading a comment from the first post, a reader enlightened me on my neglect to go into detail about what ATP is or what is stands for. So, before I dive into the final energy system, aerobic glycolysis, I’m going to briefly talk about what ATP is! Let’s begin!

ATP Revisted

ATP stands for Adenosine TriPhosphate. This is the molecule our body synthesizes from all these different energy systems in order to make us move in all the ways that we do. Chemically, it is composed of a DNA molecule known as Adenine (in this case, adenosine), ribose, and phosphate groups.

Adenine is one of the four components that create DNA (Only four things known as nucleotides make up your entire DNA sequence! That’s amazing!). Adenine then binds (connects) to ribose, a sugar molecule. Finally, this sugar is bound to a chain of 3 molecules known as phosphate groups.

What makes ATP the OG energy molecule is those phosphate groups. These are known as “High-energy bonds” that, when broken off the ATP molecule, release A TON of energy that our muscles, cells, etc. use to do all the activities that we do.

When a phosphate group is removed from ATP, it becomes ADP (Adenosine DiPhosphate) and AMP (Adenosine MonoPhosphate) when two groups are removed. Here’s a nice visual from Khan Academy¹ to summarize what I mean by molecules, phosphate groups, etc.

Untitled design (8)

Phew. Okay. That covers ATP. Now! Onto the star of the metabolic show, aerobic glycolysis!

Aerobic Glycolysis

Why do I refer to this energy system as the star of the show? This is the system that not only provides the most energy, but it is also in use the most amount of time because typically, we aren’t jumping, sprinting, etc. We only do that for a relatively short period of time (even though it may feel like it never ends).

When we’re just walking, sitting, working, doing normal people stuff, we’re using this energy system. ADDITIONALLY, this is the primary energy system in use when we’re doing light to moderate-intensity exercise for a long period of time.

What’s the reason behind this? Well, for everyday stuff, we’re not in dire need of energy at that very moment like we may be if we’re sprinting away from a bear or angry girlfriend (which are equally dangerous).

Our bodies are built for survival. If it doesn’t need energy ASAP, it’s going to break it down slower but provide more of that energy on a per-cycle basis. What I mean by this is for each “cycle” completed of aerobic glycolysis, we get more energy molecules, meaning more energy for us! Woohoo!

After the lactic acid cycle is depleted/unable to work further, this system kicks in for the remainder of the exercise. Interestingly, long-distance runners can actually notice when their metabolism “switches” to aerobic glycolysis. It’s characterized by fatigue, tiredness, and a feeling of “hitting the wall”. They feel this way because energy isn’t being produced as quickly as we need it.

Also a fun fact, this system is aerobic which means it requires oxygen to start working. Ever notice that you start breathing more the longer you exercise?? You’re taking in that oxygen for a reason. Your body knows when it needs oxygen, and so your brain will tell you to breathe more to take in more oxygen! BOOM!

Why does it take so long to acquire this energy? Aerobic glycolysis relies on fat consumed in the diet or from body fat stores once dietary fat is consumed in order to synthesize glucose and/or ATP. I say ‘and/or’ because when we use fat as energy, it actually breaks into its two components (glycerol backbone and three fatty acid chains, refer to this article on fat for a refresher on the structure of fats).

Glycerol produces a small amount of glucose while the fatty acid chains cannot be converted into glucose; so they have their own metabolic pathway to produce ATP. Creating glucose from sources other than carbohydrate (protein, glycerol, lactate) is known as gluconeogenesis². We actually saw this during the lactic acid cycle! Lactate becomes glucose during the cycle!

Back to the question, fat, as an energy source takes a while because of those damn fatty acid chains. These chains are composed of a lot of carbon atoms that go through a lot (a lot!) of steps to become usable energy. This metabolic pathway is known as Beta-oxidation or fatty acid oxidation.

Why Does This Matter?

Well I’m not going to teach you something if it’s not important! Also, this information will be on the test next Thursday, so make sure you study it.

It’s important because if you do long-duration exercise, you will be using this energy system for most of the time. Additionally, this is the system in use most of the time throughout daily life!

Yeah. So what?

So what? SO WHAT?! This is a sign for you to see that dietary fat is not bad for you. It’s an energy source that is very important for prolonged energy production! Also, if you know that you’re going somewhere without food for a few hours, having fat in a meal prior will help you stay energized. ‘Energized’ does not equal ‘full’ though, keep that in mind. Combat stomach emptiness with fiber and protein!

But, if you need energy for a long time because you won’t get to eat, having some fat from nuts, peanut butter, oils, avocados, seeds, etc. will keep you moving forward! THAT’S why this is important, dammit.

Here is a helpful graph from Precision Nutrition³ to summarize what these last two posts were about. I encourage you to read that linked article too. It’s super informative!

As you can see, ATP stores in the muscle are used up almost instantly, followed by the ATP-PC system (Creatine Phosphate) in purple, then the lactic acid system in green after about 2 minutes. Finally, aerobic glycolysis kicks in for the remainder of the activity at the expense of exercise or activity performance aka “Hitting the wall”.

Image result for energy system use over time


  • ATP is the primary energy molecule made of adenosine, a sugar molecule, and phosphate groups
  • Aerobic glycolysis kicks in after the lactic acid system and continues pumping out energy for the duration of exercise or the activity being performed.
  • Dietary fat and body fat are the primary fuel sources for aerobic glycolysis (Does not mean you can sit on your ass and claim you’re burning body fat. It doesn’t work like that.
  • When used for energy, fat is broken into two components that enter two different metabolic pathways (gluconeogensis for glycerol and beta-oxidation for fatty acids)
  • If you can understand what system is used, you can better prepare meals for exercise or if you’re going to be out for the day!

Do you like posts like this where I explain nutrition science topics?? I love talking about this stuff because I feel that science needs to be communicated to the public more often and in a better way. That’s one purpose of this blog if you couldn’t tell by now! Let me know what you think in the comments! All feedback welcome! Thanks for reading!


¹Basic concepts in bioenergetics: phosphoryl group transfers and ATP hydrolysis

²Glucose Can Be Synthesized from Noncarbohydrate Precursors

³All About High Intensity Interval Training (HIIT)

How Do We Acquire and Use Energy From Food? Part 1

Ever think about how we, as the crazy people we are, get energy to do everyday stuff? Walk, run, jump, pick up kids, throw said kids because they’re annoying, even getting out of bed! Everything you do takes some bit of energy!

Where do we get that energy? Caffeine? Well, it may seem like it, but caffeine provides no ACTUAL energy. It’s just a stimulant that makes you FEEL energized. There’s a huge difference. We derive our energy from food in the form of calories from carbs, protein, and fat (and alcohol)!

But, let’s dig exactly does your body break food down into components that it can use for energy? More importantly, why is this important? Well, if you know what and how your body fuels itself, you can provide it better fuel at better times to feel better, without stimulants!

So, what gives us the energy to live the awesome lives we live? These awesome things known as energy systems!

Energy systems are typically discussed in the context of exercise because that’s one of the few times that all the systems may be utilized during one time period. Typically, at rest, only one (aerobic glycolysis) is used; but, keep this in mind, whenever you’re doing strenuous work like moving or lifting heavy objects, the other sports-related systems may be in use.

There are a few ways our bodies use the different fuel sources. It all depends on the activity you’re doing and the amount of energy needed to perform that activity. Let’s begin by talking about what our body actually uses as energy. Hint: It’s not glucose (technically).


ATP is THE energy molecule. Whenever we’re doing literally anything, we’re using ATP. While we can acquire ATP from different forms (carbs, fat, protein, alcohol, etc.), it all funnels into ATP and some other secondary molecules. This happens because we have different systems in our bodies to break down the different macronutrients. With that in mind, let’s talk about what they are, when they’re used, and why this applies to you.

In part 1 of this series, I’ll talk about the exercise-focused energy system, Anaerobic Glycolysis; but remember, whenever you’re doing intense, strenuous work, these systems are working, so don’t skip this if you don’t exercise! Part 2 will cover the more general system known as Aerobic Glycolysis.

Anaerobic Glycolysis

To begin, we discuss Anaerobic Glycolysis. This refers to systems that generate energy WITHOUT the use of oxygen. Oxygen is the primary distinction between aerobic and anaerobic systems. Oxygen as a chemical has some interesting properties to it that allows us to create energy in different ways. The next two systems-Creatine Phosphate and Lactic Acid Cycle-do not need oxygen to create energy. Let’s begin!

Creatine Phosphate System

This is the very first system used when doing typically high-intensity exercise or activity. Anything from deadlifting 1000lbs to picking up some heavy furniture. This system is used for, as Deadpool says, MAXIMUM EFFORT. Creatine phosphate is made up of a few atoms-the things on the periodic table-to make a molecule (Chemistry 101 lesson right there, you’re welcome). This molecule, Creatine Phosphate, will donate some atoms to make ATP.

All of this occurs inside the muscle tissues, so energy is able to be generated very quickly, hence why it’s used first; but there is a very limited supply of creatine phosphate in muscles, so this system will deplete in a matter of seconds. So why does this matter? Well, if you’re an athlete, or someone who just likes to exercise (running, lifting, etc.), then this is what jumpstarts you whenever you start your exercise! If you’re going to sprint, that quick jolt of energy is this system at work. Knowing what systems are at work can allow you to better fuel up for training! Creatine is most commonly found in meats. Vegans and vegetarians may have to supplement it.

Creatine supplements work by flooding your muscles with creatine, thereby allowing this system to last longer than a few seconds and continue to produce energy quickly which can lead to better training sessions since your endurance is improved! This is some seriously cool stuff. Think about it next time you pick up something heavy, or move some furniture!

Lactic Acid Cycle

After the Creatine Phosphate system is exhausted, the body shifts over to the lactic acid cycle for up to roughly 2 minutes of continuous work (think two minute run or two minutes straight of lifting). This is typically when someone will start to “Feel The Burn”, especially in terms of weight training. The reason this occurs is because there is an accumulation of hydrogen in the muscles, which causes the muscle tissue environment to become more acidic.

What this results in is that fatigue and tiredness experienced when lifting weights. The acidic environment inhibits the working muscles from contracting and causes that burning sensation and fatigue.

So why do we use this system if it’s just going to burn us? That’s some BS.

Not quite, dear reader!

The lactic acid cycle is great in its ability to produce energy quickly and for a relatively long time. If we couldn’t produce energy this way, we’d be pooped much quicker. Here’s how it works:

The cycle is between the working muscles and your liver. The things that are cycling are glucose and lactate. Remember glucose? That’s the primary source of energy and ATP and guess what? It still is in this case! As glucose enters the muscle cell, the glucose will produce some ATP for the immediate energy demand and then be converted to lactate.

Then, this lactate will travel to the liver to be converted back into glucose. When converted back to glucose, the lactate also produces some ATP for immediate use. The lactate (now glucose) will travel back to the muscle cell to produce more ATP and continue the cycle until the hydrogen atoms inhibit further muscle contractions.

As you can probably imagine, this system pretty much produces energy on demand, meaning that there is none stored for future use. The ATP that is synthesized is immediately used.


Once again, this system only lasts for a few minutes, then the aerobic glycolysis systems kick in and produces a TON of energy but at a slow pace. This will be the topic for part 2 next week! Stay tuned! Check out my other articles about the sources of ATP (Protein, carbs, and fat) to learn more about the awesomeness of our body’s interaction with food! Thanks for reading!

  • The body utilizes the macronutrients through different energy systems for different demands of energy
  • Higher energy demand is derived from anaerobic glycolysis systems
  • The Creatine phosphate system is the initial system used for high-intensity work but only lasts a few seconds
  • The Lactic Acid Cycle allows us to work at high intensities for a couple of minutes until muscle contraction is no longer possible. This is accomplished by cycling glucose and lactate between the liver and muscle cells.


New Info. About Sodium and Blood Pressure. Is There an Association?

Recent research conducted by Boston University’s School of Medicine has challenged the notion that blood pressure is negatively impacted by sodium intake. Previously, the idea has been that as you increase your intake of sodium, primarily from salt, blood pressure worsens and leads to increased risk for stroke and other complications. Lynn L. Moore and her team presented their research that goes against this idea.

Disclaimer: I was only able to read the abstract, as I could not find the whole study. I am not sure if it’s available publicly yet since it’s a novel study. With that in mind, some of what I say may be misinterpreted on my part simply because I didn’t have complete access to the paper. I will do my best to avoid this while still giving you good, useful information. Hang with me here!

So, what they found was very interesting. First off, subjects were classified into five groups of increasing sodium intake. Over the groups, the average systolic and diastolic blood pressure levels were quite similar¹, even as intake increased.

Next, potassium intake had an inverse relationship with blood pressure¹. Basically, as intake of potassium increased, blood pressure levels fell. No surprise there. In addition, associations for calcium and magnesium intake were noticed that were similar to potassium (inverse relationship)¹.

Lastly, and probably, the most significant finding, the researchers also had a group where they observed the combined effects of sodium and potassium. Those with the lowest intakes of both had the highest blood pressure and vice versa¹.

What does this mean? It means eat your frickin’ vegetables. Vegetables are LOADED with potassium, and people are certainly more likely to be deficient in potassium than sodium. It’s important to note that just because this study did not find an association between blood pressure and sodium intake does not mean you can go down all the soy sauce and salt you want. In many cases, high-sodium foods are those that are highly processed, containing a lot of calories and little nutrients (like potassium).

These findings suggest the same ol’ story: obtain most of your foods from whole sources (whole grains, fresh or frozen fruits and veggies, etc.) and save some room for your personal treats. This study also suggests that you can enjoy high sodium foods in conjunction with a high intake of potassium. As we saw, high intakes of both did not show an increased risk for high blood pressure. Load up your stir fry with vegetables!

Another important note is that this is simply one study on a topic that is controversial. As I said earlier, research has been published to support both sides of the argument. Learn how your body responds to sodium. Try increasing/decreasing your intake for a week or two and check your blood pressure again to see if improvements were made. Or, in the case of increasing it, if there was no change, you may be able to add in more. Keep in mind, if you increase your sodium, your potassium intake should be moving with it.

Athletes and Sodium Intake

This is an important distinction to make. If you’re an athlete, sodium is an essential nutrient that you should not be skipping out on. Sweating results in the loss of sodium. Some people are even known as ‘salty sweaters’ and eliminate a lot of sodium through sweat. If too low levels of sodium in the blood occur, this is known as hyponatremia. The Mayo Clinic notes that these conditions could occur if hyponatremia ensues:

  • Nausea and vomiting
  • Headache
  • Confusion
  • Loss of energy and fatigue
  • Restlessness and irritability
  • Muscle weakness, spasms or cramps
  • Seizures
  • Coma²

Obviously, none of these issues are good for an athlete. So takeaway for this portion of the post is to make sure, if you’re an athlete, that you’re replenishing yourself with not just water, but some type of source that contains sodium and the other electrolytes. This will ensure you’re fully hydrated and ready for whatever is next.

Takeaway Points

  • Enjoy your sodium, but make sure your potassium intake is near similar to your sodium intake (Vegetables and legumes [think beans] are an awesome, easy way to accomplish this)
  • Don’t go HAM on the sodium (lolz, get it?)
  • Learn how your body responds to sodium by playing around with your intake.
  • If you’re an athlete, don’t be afraid to have sodium for training. It’s essential for good workouts and performance.
  • Talk to your doctor about your blood pressure and learn ways of improving it if need be or simply to understand how to manage it better

Have any burning questions or feeling a little salty after reading this? Post your comments below! Thanks for reading!