Balancing blood sugar levels is one of the foundations of eating and is the number one thing I talk about in a first session with a client. Why? Because no matter what eating style you choose to follow or what is going on in your body (a digestive issue, hormone imbalance, anxiety) having unstable blood sugar levels is often one of the root causes for symptoms - and if you can address the root you can start feeling better, sooner.
What is blood sugar?
Blood sugar refers to the concentration of glucose in our bloodstream. Glucose is our body’s preferred energy source. When we eat food, carbohydrates break down into glucose and head into our bloodstream so we can use it as energy. In a fasted state our body only has ~4 g of glucose circulating around.  When the body detects a rise in blood sugar, the pancreas will release a hormone called insulin to bring the glucose from the blood and into the cell to use for energy.
Think of insulin like a taxi cab driving around picking up sugar in the blood and taking it to where it needs to go (the cell). Insulin acts like a lock and key - plugging into the cell to allow glucose to enter. We either use glucose for energy right now or store in the muscles or liver for later. We can store up to ~100 g of glucose as glycogen in the liver and ~400 g in muscles to use as energy later on.  Anything extra will covert into triglycerides for storage in our fat cells.
Once sugar has moved out of the blood the pancreas detects this decrease and releases another hormone called glucagon, which signals to cells to stop storing glucose and blood sugar remains at a stable level.
If you were to graph a day’s worth of blood sugar levels on a chart you would want to see a wide and shallow wave (like a calm ocean). What you wouldn’t want to see is very a steep and narrow wave (like a crazy stock market). Keeping blood sugar levels stable helps with energy levels and mood throughout the day.
How do blood sugar levels become high?
When we consume more energy than we can use right now or store for later, eventually the cells reach their storage capacity and stop responding to insulin bringing them more glucose. The pancreas is still producing insulin, but cells are not responding to it. This is called insulin resistance. Think of it like the cells have changed the locks so the insulin key no longer fits. When the insulin gets released but it can’t shuttle all the sugar in the cells and you are left with a high concentration of sugar in the blood. Left unchecked or continued over time can lead to type 2 diabetes - a chronic condition that affects the body’s ability to manage blood sugar.
How do blood sugar levels become low?
Elevated blood sugar is not the only problem with blood sugar. Blood sugar drops can occur when we consistently skip meals (like never eating breakfast or skipping lunch because we’re too busy), go long periods of time between meals, . We all may have experienced feeling ‘hangry’ at a time or another. When this happens we feel irritable, shaky, and it doesn’t matter what we eat as long as it’s NOW. This can lead to a cycle of eating more than we planned or want to (less likely to listen to our hunger/fullness cues) and restrict later on to ‘make up’ for overeating. This keeps us stuck in a restrict-binge cycle in our minds and our blood sugar on a spike-crash rollercoaster. 
What contributes to high or low blood sugar?
What we eat (fast carbs without enough protein or healthy fat)
Our eating pattern (inconsistent timing or skipped meals)
Lack of good sleep
Excessive high intensity exercise
Toxins (in our food or environment)
Why is a normal blood sugar level important?
The body wants to maintain a stable blood sugar level. Blood sugar spikes and drops over time can deplete essential nutrients, put stress on the body, affect the gut, lead to inflammation, worsen our mood + mental abilities, and alter our ability to manage blood sugar. Overall, if our blood sugar levels are not balanced we do not feel very good, energy is low, and we just don’t show up as the best versions of ourselves.
How do I feel if my blood sugar is high or low?
Symptoms or risks of high or low blood sugar include:
Feeling nervous, jittery, irritable, or have a headache throughout the day
Feeling lightheaded (especially upon standing up)
Feel better after meals
Night sweats (non menopausal)
Sugar, carbohydrate, or alcohol cravings
Energy or mood drop after eating sugar, carbs, or alcohol
Excessive thirst or increased urination
Fatigue or low energy
More awake at night or having trouble sleeping
Trouble exercising - feeling depleted instead of energized after a workout
Family history of diabetes, hypoglycemia, or alcoholism
If you mark of more than 3 you may be struggling with blood sugar fluctuations throughout the day.
What are problems associated with imbalanced blood sugar levels?
High blood sugar is a serious problem and can lead to various health issues. The condition that comes to mind for most people is type 2 diabetes, but there are many other complications such as cravings, fatigue, weight gain, and increased appetite that can occur early on. In extreme situations elevated blood sugar may also lead to stroke. 
Common issues related to imbalanced blood sugar:
Pre-Diabetes + Type 2 Diabetes
How does my blood sugar level affect my hormones?
Consistently elevated blood sugar levels leave our body in a state of physical stress and inflammation. Stress meaning elevated cortisol and if our cortisol remains high overtime, it can affect our thyroid and sex hormone balance. The body will give all of its resources to cortisol to protect us from stress.
On the flip side, when the body experiences any form of stress, positive or negative, physical, mental, or emotional, it will activate cortisol, the stress hormone. Cortisol gears the body up to handle the stressor. Sugar is released into the blood stream for easy-to-access energy. Problems arise when we're in a state of constant stress and repeatedly turn on this response.
Curious about your hormone levels?
What labs tests should I get to monitor my blood sugar LEvels?
Hemoglobin A1c: average of your blood sugar levels of the last 3 months
Fasting Blood Sugar: morning blood sugar level before eating
Fasting Insulin: morning insulin level before eating, tells you information about how well your body is processing blood sugar
What are normal blood sugar levels?
Hemoglobin A1c: less than 5.7%
Fasting Blood Sugar: less than 100 mg/dL
Fasting Insulin: levels in the single digits
While the normal A1c cut off is 5.7%, this correlates to a blood glucose level of 117 mg/dL. If we want optimal levels, aim for an A1c around 5.0%. 
What are high blood sugar levels?
Pre-Diabetic Range: 5.7 - 6.4%
Diabetic Range: greater than 6.5 %
Fasting Blood Sugar:
Pre-Diabetic Range: 100-125 mg/dL
Diabetic Range: greater than 126 mg/dL
Fasting Insulin: levels in the double digits
Insulin levels can be elevated in two cases:
Insulin Resistance: the body is not responding to insulin as well (remember insulin is like a lock and key to allow glucose into the cell? in insulin resistance it’s like the locks have been changed and insulin is no longer the right key so glucose remains in the blood)
High Blood Sugar Levels: leading to the release of more insulin to reduce blood levels
What are low blood sugar levels?
Fasting Blood Sugar: less than 70 mg/dL
What to Do
HOW DO YOU MAINTAIN HEALTHY BLOOD SUGAR LEVELS?
When I talk about balancing blood sugar levels, I always say remember these two things:
Eat consistently throughout the day
Try to avoid long gaps between meals or skipping meals
Include high quality lean protein + healthy fat at each meal
Both protein + fat help to prevent blood sugar spikes
Food tips for Balanced blood sugar levels
[These are guidelines not food rules - I always encourage you to listen to your body. You know you best.]
Eat Lots of Fruit + Veggies (Fiber)
Eat Protein at Most Meals
Eat Healthy Fat at Most Meals
Choose Slow Carbs
Eat Every 4 to 6 Hours
Enjoy Sugar as a Treat
Eliminate Sugar Substitutes
Focus on Whole Foods
Incorporate Herbs + Spices
Include Supplements as Needed
Lifestyle Tips for balanced blood sugar levels
Get Enough Sleep
Take Away Message
I want to point out: carbohydrates or sugar are not the enemy. We need glucose for energy and motivation throughout the day! The goal is to maintain stable blood sugar while tapping into your own hunger + fullness cues by incorporating whole unprocessed foods, eating consistently throughout the day, balancing meals, incorporating ways to manage your stress, and learning to work with your body, not against it.