Glucose is one of your body’s primary energy source. It floats around in your blood, to be used by your brain and muscles as fuel. It is neither bad nor good, but rather needs to be kept at the right amount. If you had none in your blood, your brain will shut down and you would die. If you have too much, it can also damage your body. Around 100 mg/mL is the sweet spot where your body runs smoothly and feels great.

If you’ve ever felt very tired or had a headache after eating, or felt hangry and low energy without food, it is possible your glucose levels caused this. This guide will help you stay in the optimal ranges and avoid these types of unpleasant symptoms, as well as prevent diseases like obesity, heart disease, metabolic syndrome, type 2 diabetes or even brain damage that can arise from daily glucose imbalances.

Thousands of years ago, glucose in food was hard to find — perhaps just an occasional berry in the woods. Our body has evolved to desire and hoard it when available. Our brain’s algorithm could be quite simple: if glucose is available, eat it. Unfortunately, that is no longer an optimal strategy. Some adjustments and conscious overrides are necessary.

Now, through modern agriculture and society, we have easy access to a nearly endless supply of glucose. Therefore, our default habits may not work well and a better understanding of these systems is useful to correctly adapt. This guide will explain how the current system works, and then give you some strategies for how to control your blood levels and hormones in our new modern world.

Why may someone care? Keeping your glucose levels at an optimal range can affect how you feel in the short term, and your health and longevity in the long term. Constantly spiking and dropping glucose can result in feeling hungry or low energy all the time, making worse food decisions and having less time focused, while also gaining bodyfat. In the worst cases, constant glucose imbalances can result in a resistance to insulin and eventually type 2 diabetes.

Properly using glucose as fuel can result in better productivity, lower risks of diseases, better eating habits and a much easier time reaching all your goals. There are dozens of other important variables to get right in your health — your exercise, sleep, protein intake, stress, etc — but glucose is a good starting point since it is foundational to many of those other endeavors. Managed incorrectly, it can make it much harder to do everything else correctly.

Unlike much other health advice on the internet, one cool thing about glucose is you can measure it for yourself. Rather than just taking our word for what meal is good or bad, you can check your own blood and see how your body is reacting. Other common advice (like eating fewer calories or reducing stress), can be harder to put into practice correctly since you can’t directly measure if you are doing it successfully.

With glucose and ketone levels, however, you can conduct a much more scientific study and derive the optimal solution much more rapidly. While everyone’s response to a food may be slightly different due to their muscle mass, insulin resistance, hormone levels, etc. the general mechanisms are the same for all humans and the best practices around healthy eating should apply to everyone.

However, if you’re afraid to use a monitor (it doesn’t really hurt, but some people do find it uncomfortable) or don’t want to pay the extra cost, you can simply read this guide to fast forward to the insights. We’ve spent thousands of dollars checking our glucose and testing various meals so that you don’t have to.

Everything you need to know for glucose management is in these 6 tips:

  • Steep spikes and drops are not good
  • Eat balanced meals and avoid snacking
  • Make your meals primarily protein & fiber
  • A little sugar after a healthy meal is ok
  • Try not to eat sugar at other times, especially not alone
  • Lift weights frequently to use glycogen & build muscle

Behind the scenes, there are many complex systems and pathways involved. This guide will teach you more about how your body works, and why these recommendations should be followed whenever possible.

How does glucose get into our blood?

This is a molecule of glucose. You have millions of these circulating in your bloodstream right now. They are keeping you alive, and allow your brain to function so it can read this article.

Let’s look at the multiple ways glucose molecules can come into our blood.

From eating glucose and other sugars

Eating sugar is an obvious and primary way you can end up with sugar in your bloodstream. If you are eating a food high in sugar, getting it into your blood stream happens quite quickly. It just needs to move from your stomach to your bloodstream, which can happen quite quickly — especially on an empty stomach.

If something is liquid (ie. a soda or sugar in your coffee), it can also be absorbed even more quickly as it doesn’t need to wait in line behind all the other food you ate. If you were to take away just one idea from this post, it would be to cut out any sugary drinks.

There is so much sugar in most foods, that you will never need to go out of your way to add more sugar to things to improve your health.

However, eating sugar is not the only way sugar can ends up in your blood. In fact, the majority of your glucose likely came from other sources...

From eating carbohydrates

Under the microscope, carbohydrates are essentially long strings of glucose stuck together. Splitting them up can take some time and happens during the digestive process. It is critical to understand that salty food sources like bread or pasta or rice are ultimately bundles of sugar, and get converted to glucose during digestion.

Eating a bowl of white rice could spike your glucose as much or more than a soda or a dessert, for example. The amount eaten also affects the severity of the spike. While eating hundreds of grams of a sweet dessert may be considered unhealthy and feel wrong both physically and mentally, eating many hundreds of grams of carbohydrates can be casually and easily done if it tastes good — though the effect on your blood sugar could be similar.

This is often mind-blowing or counterintuitive to people, with the incorrect assumption that only sweet items can affect blood sugar.

Certain sources can unbundle more quickly or easily, while others (often less processed or higher in fiber) may be harder to digest and convert into glucose. Those can act as more of a time-release, and are generally preferred.

Typically, the more processed a food is the more rapidly it uncompresses into pure sugar. In this case, speed is bad, and an even distribution of energy is the most useful one. Other carbohydrates like fiber may not convert to glucose at all, but in general you can assume the entire carbohydrate content in a nutrition label will end up becoming glucose in your blood soon after eating.

For example, for members who track their glucose in Gyroscope (with a continuous glucose monitor), rice is often the most surprising spike, which can be found in meals like sushi or as a common side dish. This should not be surprising, because the nutrition label for a cup of white rice says 45g of carbohydrates, with only 4.3g of protein and 0.4g of fat. A can of coca cola has about 39g of carbohydrates, for context.

Releasing stored glycogen

Your brain needs glucose, but that doesn’t mean it needs to be eaten constantly. The body would be a terrible system if it just shut down after a few hours of no sugar. Your body stashes glucose for later as glycogen, which is distributed across your muscles and your liver.

Ironically, constantly eating glucose (and having correspondingly high insulin levels) can make it harder to use the stored glycogen. Fasting occasionally or getting in the habit of dipping in and out of your stored glucose and ketones can help to prepare you for smoother transitions.

Sometimes exercise can help to shake things up and release the sugar. For example, during running sometimes people can actually have a big spike in sugar. Where did that come from if you didn’t eat food while running?

From protein or fat

Since you would die without the baseline amount needed for brain function, your body doesn’t leave it to chance and can make its own glucose from other substances like protein or fat. This is done through a process called gluconeogenesis.

This is how people are able to survive fasting for a long time or eating a ketogenic diet with limited carbohydrates. Eating the carbohydrates helps save your body some work, but even with a low amount of carbs your body will survive and be able to make the glucose it needs. The process does require energy, but fortunately most humans have massive amounts of energy stored.

If you’ve been worried about accidentally shutting down your brain and dying after a day of not eating glucose (a common and logical concern), don’t worry. That is unlikely to happen.

Your current glucose levels are likely determined by a combination of all these sources. With optimal physical and metabolic health, your body can use these different tools to self-regulate and keep you around optimal ranges of 100 ng/mL (or around 50-80 if ketones are also being used).

How does glucose get used?

Those are the common ways glucose is added to our bloodstream, but there are many ways it is used and reduced as well. Ultimately all these inputs and outputs result in an equilibrium.

For your muscles

Moving your muscles uses glucose through a variety of chemical reactions and fuel sources. This can vary depending on the type of movement and muscle fiber (slow twitch or fast twitch, etc.). Even simple exercises like walking can help to divert glucose after a meal. Therefore, walking after every meal is a useful tool to help stabilize your blood levels. Walking before can be good too but may not have the same protective effect.

For brain activity

Your brain uses glucose and is one of the primary consumers. It can also use blood ketones, but there is a baseline requirement of glucose even then.

In some cases this can be a large amount of energy used, but don’t overestimate it. For example, if you are just sitting on the couch watching TV it is likely that you’re not burning many calories in brain energy.

For heat

It is often overlooked, but keeping your body warm takes a lot of energy. A calorie is actually the amount of energy it takes to warm a gram of water. Your body has a lot of water, and keeping it all at body temperature takes a significant amount of your total energy expenditure (see the calorie guide for more details).

If you are somewhere cold, more energy may be burned than if you are already warm and cozy. If you have a continuous glucose monitor, you can try going somewhere warm like by a fireplace or a hot tub to see this effect for yourself. Conversely, you could go out into the cold and may see your glucose levels drop.

This can also have implications for the temperature at night, especially if having a large meal or a lot of sugar before sleeping.

Into glycogen

Glucose in the blood stream can also be sent into glycogen stores in muscles and liver. This process is ushered along by the hormone insulin. This assumes there is some space and not a lot of glycogen already there. Therefore, using up the remaining amount (through time spent fasted for the liver, and moving your muscles for the muscles) in between meals can help to keep this system working smoothly.

Into bodyfat

Ultimately, energy can be converted into bodyfat as well. Especially if all the other spots are full and there is an excess of energy, the surplus can be stored as fat and kept for a rainy day.

This may seem inconvenient but is an essential part of staying alive. However, constantly overconsuming food or having elevated glucose levels, can result in storing more bodyfat than useful.

As you can see, there are many variables here. This gives you many control surfaces to keep your glucose in check.

Ate a lot of sugar? You can also walk it off. Didn’t get enough one day? Your liver can save the day and release some of its stash. When all these systems work smoothly, we can live our lives without every thinking twice about glucose levels or how we are staying alive.

It also helps explain the mechanism of many habits considered healthy — eating high protein food or meals like salad are effective because there is not much sugar, while typically unhealthy meals like pizza are so partly because of the large amount of sugar they produce (especially combined with their hyper-palatability which encourages eating hundreds of grams worth). Walking frequently helps to use your glycogen stores and improves insulin sensitivity, fasting can also help with that. Being sedentary and losing muscle mass, on the other hand, would lead to having less spots to put glucose and more pressure on your liver and bodyfat.

Insulin Resistance

In a healthy human, all these systems work smoothly in the background. Whether you eat a healthy meal or one loaded in sugar, your body figures it out and business continues as usual. Over time, this system can start to go wrong.

The most common scenario is called insulin resistance. It is estimated that more than 1 in 3 Americans are insulin resistant or prediabetic, though only a few actually know about it. This often corresponds to being overweight, but can also happen even in people who are at a healthy or low weight.

Fortunately, it can be reversed if detected early. If uncontrolled, it can result in developing Type 2 diabetes and lead to many more health complications that may be difficult or impossible to reverse later — like heart disease or death.

Since insulin resistance, obesity and the related set of diseases it causes is currently the leading common cause of death, it is worth spending some time understanding how it happens. This could help you avoid it, or even if you are in great shape help you keep all your friends and loved ones safe as well.

The dangers of insulin resistance or prediabetes

Resistance, or tolerance, can be formed from constant exposure to anything. If you drink a lot of alcohol, you will start have a higher tolerance to it. If you are constantly hearing very loud noises, you may start to lose your hearing — a resistance to sound. Like in the story of the boy who cried wolf, if any chemical is used many times a day your body can stop reacting to it as efficiently, through adaptation or damage. Insulin is released into your blood (from your pancreas) when you eat food, especially sugar, as a response to glucose in your blood.

Insulin resistance comes from repeatedly and excessively using insulin, to the point where your body becomes less reactive to it and no longer able to handle sugar. Type 1 diabetes means your body just doesn’t have any insulin to produce, but Type 2 comes from having too much. Type 2 diabetes can develop from obesity or constantly unstable glucose levels. Usually, insulin triggers extra glucose to get stored in your muscles and your liver, and in your bodyfat. After eating a big meal, this is a necessary process, and keeps your blood from reaching toxic levels.

As you saw above, the blood only stores a very small amount of energy. Your muscles, liver and bodyfat keep the rest. It is important to realize those are the only places the energy can be stored! The body originally evolved to be very efficient with energy. After billions of years of energy scarcity, digestive systems have evolved to be very greedy.

Just like you would almost have to pick up a hundred dollar bill if you saw one on the floor, your body needs to take all the available energy from your food. When anything is digested, all the available energy is always extracted! Therefore, what you eat has powerful implications for the rest of your body.

In a healthy individual, there should be plenty of free space to temporarily stash any extra glucose. There’s free space in your liver, your fat cells, your muscle glycogen, etc. that acts as a buffer, storing excess energy after a meal and then releasing it for the next few hours as needed.

Imagine you have a big empty house, so you invite some friends to visit. They could sit on your coach or stay in an extra bedroom, and then leave after a few hours or days. However, what if you invited 10 friends over? Or the people from last week never left. Or 100 people came for a big party. The couch is eventually full of people, and any new visitors may need to stay in your bathtub or kitchen or your bed.

Let’s say new people keep showing up every day and are hanging out on the street or in the hallway, ringing your doorbell. You can’t leave them there, so you must invite them in like a good friend!

At that point, it would be wise to kick everyone out before continuing. If you kept inviting people in and they never left, or fewer leave than come in, eventually your house will get quite crowded. Someone with a huge mansion may have longer, but ultimately it would happen to anyone. Once there are a hundred people crammed in your apartment, simple things like answering your door could become challenging.

This is essentially what happens with insulin resistance. The “friends” are glucose molecules, your bedrooms are your muscles (capable of letting many friends stay for a while), your liver is your living room (capable of storing a few more in the short term). Inviting someone to come in who is ringing your doorbell is like deploying insulin.

Eventually, if your house is already full of 100 people, you won’t even be able to answer the doorbell and let any new people in. That is what happens if you eat sugar and your liver, muscles and bodyfat are already packed to the brim. We could look at the number of people ringing the doorbell at different houses to get a sense of which ones are overflowing. A few could be considered prediabetes, while a hundred people banging on a door to be let in could be a severe case of Type 2 Diabetes.

Throwing a party is fine occasionally, and so the house could be filled with people for a short while. Then when everyone goes home, it gets cleaned up, and you’re back to normal. Some could argue that is the whole point. However, what happens in the case of insulin resistance or diabetes, is a constant overflow of new visitors with the previous never leaving, trashing your body in the process without any opportunity to clean up.

Metabolic health is a spectrum, and not something that deteriorates overnight. About 33% of adults in the US (88 million according to the CDC) are already prediabetic, though about 84% of them don’t know it yet. Insulin is not the only chemical that develop a resistance. With poor metabolic health, a resistance to leptin or other hunger hormones could cause you to feel constantly hungry or low energy despite eating a large meal. Once these cycles start, they can be very difficult to break out of.

However, the solution to avoid or reverse these is quite simple. Simply don’t have constantly high levels. Occasionally high levels, followed by low levels to rest and reset, is generally a good strategy for all the body’s systems — brain activity, heart activity, muscle activity, and also metabolic actvitiy.

Measuring your levels

You can keep an eye on your glucose with a traditional monitor (more accurate and cheaper) or CGM (more automated and less effort, but pricy) to see your blood sugar graphs.

Everyone should track their glucose with a classic monitor for at least a few weeks before upgrading to a CGM. Generally, both are used together to calibrate your metrics and get full coverage. Skipping normal trackers and going straight to a CGM is kind of like learning to drive with a Ferrari — quite expensive and you’re unlikely to get a full understanding by skipping the basics.

Glucose monitoring can be effective for those addicted to sugar, at high risk for diabetes, or not sure whether carbs are having a negative effect on their body. Seeing the graph go up and down can be more motivating to stop than just reading it in a guide somewhere.

Avoiding high glucose spikes and reducing insulin resistance are important for weight loss, but also general health even if you are happy with your weight. There are a few easily available tools to focus on those metrics to understand and prioritize your glucose levels.

Most ketone and glucose monitors can be easily purchased on Amazon for less than $50, while some more exotic monitors designed for Type 1 Diabetes patients (who use them to constantly administer insulin) have more limitations and can require a prescription.

  • Precision Xtra ($50 + refills)
  • Keto Mojo ($50 + refills)
  • Food XRAY ($99/month)
  • Freestyle Libre ($200/month) (requires doctor’s note in the US)
  • Dexcom G6 ($400/month) (requires doctor’s note in the US)

If you are not following those guidelines and have a higher sugar and processed food intake, or if you are already obese and have developed symptoms of prediabetes, then it will be useful to track and improve your glucose until you are back to a healthy baseline.

On the other hand, ketone monitoring can also be a useful tool for those who are already metabolically healthy to pushing themselves to their limits with a ketogenic diet or longer fasts.

The simplest approach is just tracking your food with the Food XRAY. You can get warned in the app about what meals are not well balanced and likely to cause a glucose spike. This is fully non-invasive, and implements the guidelines mentioned in this guide — like avoiding excess added sugar from processed foods, and prioritizing high protein whole foods.

For 90% of people, just following those recommendations will be sufficient and save them hundreds of dollars a month. Others may want to see for themselves. In that case, we suggest you prick your finger 30 minutes after a meal to get an official reading of your glucose (or ketones if low-carb). If the number is much higher than 100, then that can be a sign of a blood sugar spike or potential developing insulin resistance.

If you are constantly finding your blood sugar levels are high after meals, a more extreme option is to set up a continuous glucose monitor. Generally only prescribed to people with Type 1 Diabetes, some people who are prediabetic may also find significant value in this experiment. These can be obtained from your doctor or purchased online on Amazon (depending on where you live). In the US, some companies will sell a prescription for a monitor for an additional fee.

There are two types of monitors on the market: the cheaper Freestyle Libre (the round one), which doesn’t have bluetooth or save to Apple Health, or the higher-end Dexcom which will automatically notify you when your glucose goes up, and save the data into Apple Health so it can be seen in your Gyroscope reports. If you are going to spend the money for a nice CGM, we highly recommend the Dexcom G6.

For extremely rapid spikes and drops, continuously monitoring may provide a better insight into the shape, while a fingerprick at the wrong time may not capture a rapid spike. However, in most cases a fingerprick will actually be more accurate since a CGM is about 30 minutes delayed from your actual blood sugar (due to looking at sugar levels in your skin rather than your blood).

The main downside here is the cost, of $10+ per day for a Dexcom CGM is not cheap. It is also not a complete solution, and only provides benefit in addition to the other food tracking. The cost is literally equivalent to buying a new Apple Watch and then throwing it away every month (about $400 for a set of sensors). Since it is so expensive, we recommend using it under the supervision of a Gyroscope coach to get the best insights and food recommendations from that expensive data.

A free alternative is to look at the graphs of other people who have done this, and copy their answers. While everyone will have slightly different reactions depending on their muscle mass and metabolic health, generally it will be close enough. For example, @glucosegoddess on Instagram posts common food swaps and her glucose levels.

The basics to remember

  • Steep spikes and drops are not good
  • Eat balanced meals and avoid snacking
  • Make your meals primarily protein & fiber
  • A little sugar after a healthy meal is ok
  • Try not to eat sugar at other times, especially not alone
  • Lift weights frequently to use glycogen & build muscle