What Is Nutrient Timing and Why Does It Matter?
Nutrient timing involves eating foods at strategic times in order to achieve certain outcomes.
It's supposedly very important for muscle growth, sports performance and fat loss.
If you've ever rushed for a meal or protein shake after a workout, this is nutrient timing.
However, despite its popularity, the research on nutrient timing is far from convincing (1).
Here is everything you need to know about nutrient timing.
A Brief History of Nutrient Timing
One of the world's leading researchers in carbohydrate timing, Dr. John Ivy, has published many studies showing its potential benefits. In 2004, he published a book called Nutrient Timing: The Future of Sports Nutrition.
Since then, many nutritional programs and books have promoted nutrient timing as the key method for losing fat, gaining muscle and improving performance.
1. Short-term blood markers: Many of the studies only measure short-term blood markers, which often fail to correlate with long-term benefits (6).
2. Ultra-endurance athletes: Many of the studies follow extreme endurance athletes, which do not necessarily represent the average person.
For these reasons, the findings in much of the research that supports nutrient timing may not apply to everyone.
Bottom Line: Nutrient timing has been around for several decades. Many people believe it's vitally important, but the research has limitations.
The Anabolic Window: Fact or Fiction?
Also known as the window of opportunity, it's based on the idea that the body is in the perfect condition for nutrient absorption within 15–60 minutes after exercise.
However, even though research on the anabolic window is far from conclusive, it is regarded as an important fact by many professionals and fitness enthusiasts.
The theory is based on two key principles:
1. Carb replenishment: After a workout, an immediate supply of carbs helps maximize glycogen stores, which can improve performance and recovery.
Both of these principles are correct to some extent, but human metabolism and nutrition are not as black and white as many people like to think.
One main aspect of the anabolic window is carb replenishment, since carbs are stored in the muscles and liver as glycogen.
However, timing may only be relevant if you are training several times a day or have multiple athletic events within a day. For the average person who works out once a day, there is plenty of time to replenish glycogen at each meal (10).
Additionally, some research actually shows training with lower muscle glycogen to be beneficial, especially if your goal is fitness and fat loss (11).
New research has even shown immediate replenishment may reduce the fitness benefits you receive from that session (12).
So although immediate glycogen synthesis makes sense in theory, it does not apply to most people in most situations.
The second aspect of the anabolic window is the use of protein to stimulate muscle protein synthesis, which plays a key role in recovery and growth.
However, while muscle protein synthesis and nutrient replenishment are important parts of the recovery process, research shows that you don't need to do this right away after a workout.
A recent meta-analysis by leading researcher Dr. Brad Schoenfeld also arrived at this conclusion, summarizing that daily protein and nutrient intake is the priority (13).
In short, if you meet your total daily needs for protein, calories and other nutrients, the anabolic window is less important than most people believe.
Two exceptions are elite athletes or people who train several times per day, who may need to maximize fuel replenishment between sessions.
Bottom Line: The anabolic window is a period of time after workouts that is said to be crucial for nutrient intake. However, studies show that most people don't need to replenish carb or protein stores right away.
Nutrient Timing Before You Train
The pre-workout window may actually be more important than the anabolic window.
Depending on your goals, the correct timing for taking certain supplements may actually aid performance (14).
This also applies to food. A well-balanced, easily digestible meal eaten 60–150 minutes before a workout may improve performance, especially if you have not eaten for several hours (16).
Hydration is also closely linked to health and performance. Many people tend to be dehydrated before working out, so it may be important to drink around 12–16 oz (300–450 ml) of water and electrolytes before the workout (19, 20, 21).
Additionally, vitamins may affect workout performance and may even reduce training benefits. So although vitamins are important nutrients, it may be best not to take them close to your workout (22).
Bottom Line: Nutrient timing may play an important role in pre-workout nutrition, especially if you want to maximize performance, improve body composition or have specific health goals.
Nutrient Timing at Breakfast
Recent research has shown that it doesn't really matter if you eat breakfast or not. Instead, what you eat for breakfast has become the hot topic.
Many professionals now recommend a low-carb, high-fat breakfast, which is claimed to improve energy levels, mental function, fat burning and keep you full.
However, while this sounds great in theory, most of these observations are anecdotal and unsupported by research (23).
And, while some studies do show greater fat burning, this is caused by the increased dietary fat intake from the meal, not because you're burning more body fat.
As with the anabolic window, the breakfast myth is not supported by research.
Nevertheless, if you do prefer a low-carb, high-fat breakfast, there's no harm in that. Your breakfast choice should simply reflect your daily dietary preferences and goals.
Bottom Line: There is no evidence to support one best approach for breakfast. Your breakfast should reflect your dietary preferences and goals.
Nutrient Timing at Night
“Cut carbohydrates at night to lose weight."
This is another diet myth, promoted by celebrities and magazines around the world.
In contrast to eliminating carbs at night, some research actually shows carbs can help with sleep and relaxation, although more research is needed on this (25).
This may hold some truth, as carbs release the neurotransmitter serotonin, which helps regulate your sleep cycle.
Based on the health benefits of a good night's sleep, evening carb intake may actually be beneficial, especially if you have problems sleeping.
Bottom Line: Cutting carbs at night is not a good tip for losing weight, especially since carbs may help promote sleep. However, further research is needed on this.
Does Nutrient Timing Matter?
For elite athletes, nutrient timing may provide an important competitive advantage.
However, the current research doesn't support the importance of nutrient timing for most people who are simply trying to lose weight, gain muscle or improve health.
Instead, focus your efforts on consistency, daily calorie intake, food quality and sustainability.
When you've got all the basics down, then you may wish to move your attention to more advanced methods like nutrient timing.
This article was reposted from our media associate Authority Nutrition.
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Hanako, a female Asian elephant, lived in a tiny concrete enclosure at Japan's Inokashira Park Zoo for more than 60 years, often in chains, with no stimulation. In the wild, elephants live in herds, with close family ties. Hanako was solitary for the last decade of her life.
Hanako, an Asian elephant kept at Japan's Inokashira Park Zoo; and Kiska, an orca that lives at Marineland Canada. One image depicts Kiska's damaged teeth. Elephants in Japan (left image), Ontario Captive Animal Watch (right image), CC BY-ND
Affecting Health and Altering Behavior<p>It is easy to observe the overall health and psychological consequences of life in captivity for these animals. Many captive elephants suffer from arthritis, obesity or skin problems. Both <a href="https://doi.org/10.11609/JoTT.o2620.1826-36" target="_blank">elephants</a> and orcas often have severe dental problems. Captive orcas are plagued by <a href="https://doi.org/10.1016/j.jveb.2019.05.005" target="_blank">pneumonia, kidney disease, gastrointestinal illnesses and infections</a>.</p><p>Many animals <a href="https://doi.org/10.1016/j.neubiorev.2017.09.010" target="_blank">try to cope</a> with captivity by adopting abnormal behaviors. Some develop "<a href="https://doi.org/10.1016/j.applanim.2017.05.003" target="_blank" rel="noopener noreferrer">stereotypies</a>," which are repetitive, purposeless habits such as constantly bobbing their heads, swaying incessantly or chewing on the bars of their cages. Others, especially big cats, pace their enclosures. Elephants rub or break their tusks.</p>
Changing Brain Structure<p>Neuroscientific research indicates that living in an impoverished, stressful captive environment <a href="https://doi.org/10.1016/j.jveb.2019.05.005" target="_blank" rel="noopener noreferrer">physically damages the brain</a>. These changes have been documented in many <a href="https://doi.org/10.1002/cne.903270108" target="_blank" rel="noopener noreferrer">species</a>, including rodents, rabbits, cats and <a href="https://doi.org/10.1006/nimg.2001.0917" target="_blank" rel="noopener noreferrer">humans</a>.</p><p>Although researchers have directly studied some animal brains, most of what we know comes from observing animal behavior, analyzing stress hormone levels in the blood and applying knowledge gained from a half-century of neuroscience research. Laboratory research also suggests that mammals in a zoo or aquarium have compromised brain function.</p>
This illustration shows differences in the brain's cerebral cortex in animals held in impoverished (captive) and enriched (natural) environments. Impoverishment results in thinning of the cortex, a decreased blood supply, less support for neurons and decreased connectivity among neurons. Arnold B. Scheibel, CC BY-ND<p>Subsisting in confined, barren quarters that lack intellectual stimulation or appropriate social contact seems to <a href="https://doi.org/10.1590/S0001-37652001000200006" target="_blank" rel="noopener noreferrer">thin the cerebral cortex</a> – the part of the brain involved in voluntary movement and higher cognitive function, including memory, planning and decision-making.</p><p>There are other consequences. Capillaries shrink, depriving the brain of the oxygen-rich blood it needs to survive. Neurons become smaller, and their dendrites – the branches that form connections with other neurons – become less complex, impairing communication within the brain. As a result, the cortical neurons in captive animals <a href="https://doi.org/10.1002/cne.901230110" target="_blank">process information less efficiently</a> than those living in <a href="https://doi.org/10.1002/dev.420020208" target="_blank">enriched, more natural environments</a>.</p>
An actual cortical neuron in a wild African elephant living in its natural habitat compared with a hypothesized cortical neuron from a captive elephant. Bob Jacobs, CC BY-ND<p>Brain health is also affected by living in small quarters that <a href="https://doi.org/10.3233/BPL-160040" target="_blank">don't allow for needed exercise</a>. Physical activity increases the flow of blood to the brain, which requires large amounts of oxygen. Exercise increases the production of new connections and <a href="http://dx.doi.org/10.1126/science.aaw2622" target="_blank">enhances cognitive abilities</a>.</p><p>In their native habits these animals must move to survive, covering great distances to forage or find a mate. Elephants typically travel anywhere from <a href="https://www.elephantsforafrica.org/elephant-facts/#:%7E:text=How%20far%20do%20elephants%20walk,km%20on%20a%20daily%20basis." target="_blank">15 to 120 miles per day</a>. In a zoo, they average <a href="https://doi.org/10.1371/journal.pone.0150331" target="_blank" rel="noopener noreferrer">three miles daily</a>, often walking back and forth in small enclosures. One free orca studied in Canada swam <a href="https://doi.org/10.1007/s00300-010-0958-x" target="_blank" rel="noopener noreferrer">up to 156 miles a day</a>; meanwhile, an average orca tank is about 10,000 times smaller than its <a href="https://www.cascadiaresearch.org/projects/killer-whales/using-dtags-study-acoustics-and-behavior-southern" target="_blank" rel="noopener noreferrer">natural home range</a>.</p>
Disrupting Brain Chemistry and Killing Cells<p>Living in enclosures that restrict or prevent normal behavior creates chronic frustration and boredom. In the wild, an animal's stress-response system helps it escape from danger. But captivity traps animals with <a href="https://doi.org/10.1073/pnas.1215502109" target="_blank">almost no control</a> over their environment.</p><p>These situations foster <a href="https://doi.org/10.1037/rev0000033" target="_blank">learned helplessness</a>, negatively impacting the <a href="https://doi.org/10.1155/2016/6391686" target="_blank" rel="noopener noreferrer">hippocampus</a>, which handles memory functions, and the <a href="https://doi.org/10.1016/j.neuropharm.2011.02.024" target="_blank" rel="noopener noreferrer">amygdala</a>, which processes emotions. Prolonged stress <a href="https://doi.org/10.3109/10253899609001092" target="_blank" rel="noopener noreferrer">elevates stress hormones</a> and <a href="https://doi.org/10.1523/JNEUROSCI.10-09-02897.1990" target="_blank" rel="noopener noreferrer">damages or even kills neurons</a> in both brain regions. It also disrupts the <a href="https://doi.org/10.1016/j.neubiorev.2005.03.021" target="_blank" rel="noopener noreferrer">delicate balance of serotonin</a>, a neurotransmitter that stabilizes mood, among other functions.</p><p>In humans, <a href="https://doi.org/10.1006/nimg.2001.0917" target="_blank" rel="noopener noreferrer">deprivation</a> can trigger <a href="https://doi.org/10.3389/fnins.2018.00367" target="_blank" rel="noopener noreferrer">psychiatric issues</a>, including depression, anxiety, <a href="https://doi.org/10.3389/fnins.2018.00367" target="_blank" rel="noopener noreferrer">mood disorders</a> or <a href="https://doi.org/10.1177/1073858409333072" target="_blank" rel="noopener noreferrer">post-traumatic stress disorder</a>. <a href="https://doi.org/10.1007/s00429-010-0288-3" target="_blank" rel="noopener noreferrer">Elephants</a>, <a href="https://doi.org/10.1371/journal.pbio.0050139" target="_blank" rel="noopener noreferrer">orcas</a> and other animals with large brains are likely to react in similar ways to life in a severely stressful environment.</p>
Damaged Wiring<p>Captivity can damage the brain's complex circuitry, including the basal ganglia. This group of neurons communicates with the cerebral cortex along two networks: a direct pathway that enhances movement and behavior, and an indirect pathway that inhibits them.</p><p>The repetitive, <a href="http://dx.doi.org/10.1016/j.bbr.2014.05.057" target="_blank">stereotypic behaviors</a> that many animals adopt in captivity are caused by an imbalance of two neurotransmitters, dopamine and <a href="https://doi.org/10.1016/j.neubiorev.2010.02.004" target="_blank" rel="noopener noreferrer">serotonin</a>. This impairs the indirect pathway's ability to modulate movement, a condition documented in species from chickens, cows, sheep and horses to primates and big cats.</p>
The cerebral cortex, hippocampus and amygdala are physically altered by captivity, along with brain circuitry that involves the basal ganglia. Bob Jacobs, CC BY-ND<p>Evolution has constructed animal brains to be exquisitely responsive to their environment. Those reactions can affect neural function by <a href="https://www.penguinrandomhouse.com/books/311787/behave-by-robert-m-sapolsky/" target="_blank">turning different genes on or off</a>. Living in inappropriate or abusive circumstance alters biochemical processes: It disrupts the synthesis of proteins that build connections between brain cells and the neurotransmitters that facilitate communication among them.</p><p>There is strong evidence that <a href="https://doi.org/10.1523/JNEUROSCI.0577-11.2011" target="_blank">enrichment</a>, social contact and appropriate space in more natural habitats are <a href="https://doi.org/10.1111/j.1748-1090.2003.tb02071.x" target="_blank" rel="noopener noreferrer">necessary</a> for long-lived animals with large brains such as <a href="https://doi.org/10.1371/journal.pone.0152490" target="_blank" rel="noopener noreferrer">elephants</a> and <a href="https://doi.org/10.1080/13880292.2017.1309858" target="_blank" rel="noopener noreferrer">cetaceans</a>. Better conditions <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5543669/" target="_blank" rel="noopener noreferrer">reduce disturbing sterotypical behaviors</a>, improve connections in the brain, and <a href="https://doi.org/10.1038/cdd.2009.193" target="_blank" rel="noopener noreferrer">trigger neurochemical changes</a> that enhance learning and memory.</p>