Be More Sensitive…To Insulin!


What is insulin?

  • Hormone: a signaling molecule produced by the body or synthetically to control or regulate the activity of certain cells or organs
  • Peptide: a small protein, a chain of amino acids (110 to be specific).
    • Peptide hormones cannot pass easily through cell membranes (like steroid hormones can) and must bind to receptors on the surface of cell membranes to create the desired action.
  • Anabolic: responsible for building (synthesizing) in the body, not breaking things down (which would be catabolic).

Where does insulin come from?

  • The Pancreas

    In an area of the pancreas called the Islet of Langerhans (I didn’t name it).
    DAD2.pngFrom Beta Cells in this area.

What causes insulin to be released from β-cells?

During digestion, nutrients from food, including fats, proteins, carbohydrates, and micronutrients, are broken down to their most basic forms and absorbed into the blood.

Ingestion of carbohydrates causes blood glucose levels to rise, and this is the primary trigger for insulin to be secreted from the pancreas into the blood stream.

Ingestion of certain amino acids can also trigger insulin release, but this is to a much smaller degree.

What does insulin do?

  • Without insulin, glucose cannot get from the bloodstream into cells of the body. Insulin attaches to receptors on cell membranes and enables the transport of glucose into cells. Glucose gets transported mainly into skeletal muscle cells and fat tissue.
  • Prioritizes the body’s use of carbohydrates as energy instead of fat or muscle.
  • Insulin also causes cells to be more permeable to amino acids, creatine, and some minerals. In muscles, this helps with growth, repair, and energy.
  • When insulin attaches to skeletal muscle it increases muscle protein synthesis (i.e. the building of muscle tissue from entering amino acids).
  • Insulin causes blood vessels to dilate, increasing the amount of nutrients (glucose/amino acids) delivered to muscle cells.

What does the glycemic index have to do with insulin?

Foods are digested at various speeds, meaning their nutrients are absorbed into the bloodstream at different rates. The glycemic index (GI) is a reflection of digestion rate for carbohydrate sources. Higher GI numbers reflect faster digestion than lower GI numbers. High GI carbs arrive in the bloodstream quickly, driving blood glucose levels up high. Insulin spikes to make use of that glucose, but afterward blood glucose may crash to low levels causing fatigue (i.e. food coma). Low GI carbs gradually enter the blood stream, so insulin levels are more consistent.


Things that raise a carbohydrate’s digestion rate (higher GI): sugar

Things that lower a carbohydrate’s digestion rate (lower GI): fiber, protein



It’s generally suggested that at most times, one should consume lower GI carbohydrates. However, there are other times, such as after a strength training workout, where eating high-GI carbs with a whey protein shake (also quickly digested by the body) is optimal for increasing nutrient uptake into muscle tissue.

Why is insulin necessary?


There are a couple reasons insulin is important:

  1. Too much sugar (glucose) in the blood is toxic to the body. Blood glucose must remain within normal levels of 75-120ml/dl.
    ->As a side note: too little blood glucose is also problematic, but that’s an issue for another pancreatic hormone called glucagon.
  2. Glucose is an important energy source for our bodies’ daily processes. Without insulin, glucose can’t get into the cells to be used as energy. The body will deplete it’s glycogen stores and then break down muscle tissue for energy.
  3. Let’s not forget the brain. In the brain, insulin receptors are present in areas that control nutrient homeostasis (keeping nutrient levels constant), reproduction, cognition, memory, neural development, executive functioning, learning, and memory.

    • I recall discussing the importance of glucose in the functioning of the hippocampus (a memory center in the brain) in my Psychology of Learning class at UCLA. My professor’s hypothesis (which he was testing on military members at Camp Pendleton) was that some symptoms of PTSD (inappropriate memory flashes) arise when, due to extreme emotional stress, the hippocampus depletes it’s glucose stores and cannot properly store memories.

Insulin Sensitivity vs. Resistance

These terms describe how sensitive the body is to the effects of insulin. When one is insulin sensitive, his or her cells respond properly to the presence of insulin. In cases of insulin resistance, cells fail to respond to the presence of insulin, blood glucose remains elevated, the pancreas releases more insulin, so blood insulin levels are also abnormally high.



Insulin resistance can be developed from diets that are chronically high in High-GI carbohydrates, and it can lead to the body’s inability to regulate blood glucose (Type 2 Diabetes).

SP_S2691NormalCellsC_Webimages 12.52.52 PM


Insulin sensitivity is considered a desired trait for good health, and it can be increased by both aerobic and anaerobic exercise. Maintaining insulin sensitivity can help with workout goals in a couple ways:

  1. More carbohydrates can get into the muscles during exercise allowing for better workout performance (because more energy!).
  2. Elevated insulin from eating or drinking carbohydrates post-workout increases amino acid uptake (building blocks for new muscle or muscle repair). It also enables faster recovery from workouts since muscle can quickly absorb glucose from the blood instead of the slow process of getting it from fat stores.

Further Reading

Sugar the Sweet Truth by Bret Contreras

Insulin by Rehan Jalali

The Muscle Building Messenger Complete Guide to Insulin by Jim Stoppani

Insulin in the Brain: Its Pathophysiological Implications for States Related with Central Insulin Resistance, Type 2 Diabetes and Alzheimer’s Disease


[1] Goulet, E.D., Melancon, M.O., Aubertin-Leheudre, M., Dionne, I.J. (2005). Aerobic training improves insulin sensitivity 72-120h after the last exercise session in younger but not in older women. Eur J Appl Physiol., 95(2-3):146-52.

[2] Van Der Heijden, G.J., Wang, Z.J., Chu, Z., Toffolo, G., Manesso, E., Sauer, P.J., Sunehag, A.L. (2010). Strength exercise improves muscle mass and hepatic insulin sensitivity in obese youth. Med Sci Sports Exerc., 42(11):1973-80.


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Don’t Stress! Let’s talk about Cortisol

2stress_jokes_600x4502What is Cortisol?

  • A hormone! It’s part of the body’s endocrine system. A hormone is a signaling molecule that the body uses to control and regulate nearby or distant cells or organs. They play major roles in many essential processes not limited to moods, metabolism, growth, reproduction, and digestion. Some examples of other hormones are melatonin, insulin, growth hormone, estradiol (estrogen), and testosterone.


  • The Stress Hormone: Cortisol’s main function is to restore homeostasis (equilibrium) in the body following exposure to stress. In response to stress, cortisol affects metabolism (encouraging higher blood sugar levels and production of glucose (sugar)), ion transport (cells hold on to more sodium, get rid of more potassium), the immune system (decreasing the immune response and inflammation), and memory (by overwhelming the hippocampus, one of the brain’s main memory centers).


  • A steroid hormone. The term steroid refers to the shape of the hormone- it has 4 carbon rings, 3 rings with 6 sides and 1 ring with 5. 0194.5-01.001.TIF
    Steroid hormones are naturally created by the body from cholesterol which also has that steroid form.

    A notable point about steroid hormones is that since they don’t have much (if any) charge (notice no + or – on the molecules above), they can easily pass through cell’s exterior membrane to the inside (including to the inside of muscle cells) where they can bind receptors and interact with DNA to make changes happen.


  • It is produced in the adrenal gland, in a part called the adrenal cortex (the outer part of the gland). The hypothalamus in the brain releases one hormone (CRH) that signals the anterior pituitary of the brain to release another hormone (ACTH) which travels to the adrenal cortex and signals for release of cortisol in the blood. (It’s called the HPA axis, or hypothalamic-pituitary-adrenal axis).


  • A catabolic hormone (in skeletal muscle). The word catabolism means “to break down” and refers to processes in the body where bigger substances are broken down to smaller components, often to release energy. (Side note: The opposite of catabolism is anabolism, which means “to build up,” and involves taking smaller parts to make something bigger. This usually requires or uses energy. Catabolic processes and anabolic processes all make up metabolism.) Cortisol selects specific macronutrients (carbohydrates, fats, proteins) to be catabolized in order to meet the body’s energy demands, often sacrificing proteins for energy when muscles’ carbohydrate storages (of glycogen) are low.


  • Forms of Cortisol
    • Cortisol, Cortisone, Hydrocortisone: primary “stress hormone” produced by the body
    • Dexamethasone and prednisone: synthetic forms of cortisone with anti-inflammatory and immune suppressing properties. Useful for things like skin disorders (anti-itch), inflammatory diseases (arthritis and asthma), organ transplant (reduce chances of the body rejecting the foreign organ), and treating people who have lost function in their adrenal glands (Addison’s disease)

 What increases cortisol?

  • Age. Higher age=higher cortisol
  • Hours slept. Fewer hours of sleep=higher cortisol
  • Inflammation and abdominal fat are both linked to cortisol levels
  • Stress. Emotional and physical. This can be from money, work, that guy who just cut you off while driving, and relationships or food intolerances, injuries, illnesses, and skipped meals (fasting).
  • Caffeine. Drinking more than 2-3 cups (8oz cups, not 2-3 Trentas) of coffee each day
  • Alcohol. High alcohol consumption causes disregulation of the HPA axis and higher than normal cortisol levels because cortisol’s release is no longer regulated.
  • Smoking.

And these cortisol increases can add together (summate) to result in even higher cortisol levels in the body.

Short- and Long-Term Stress:

  • Acute (Initial, Short-term): This is your familiar “fight or flight” response where the body mobilizes (catabolizes, or breaks down) energy reserves (of fat, protein and carbohydrates) so you have enough energy to fight or get away. Cortisol and adrenaline increase while DHEA and testosterone decrease. Heart rate, blood pressure, breathing rate, body temperature, and sweating increase along with anxiety, nervousness, headaches, heartburn, and irritability.


  • Chronic Stress (long term): High cortisol and low DHEA/testosterone cause muscle loss,  fat gain, and decreased integrity in bone and other tissues (heightened catabolic processes, delayed repair/immune mechanisms). Other symptoms of chronic stress are weight gain, fatigue, blood sugar fluctuations, heightened appetite and carb/sugar cravings, muscle weakness, and increased susceptibility to illness. Sex drive is often reduced as well. Chronic stress can really turn into a self-propagating cycle that’s hard to escape and researchers are recently uncovering many relationships between elevated cortisol levels and numerous health ailments.

Stress is BAD, why do we NEED cortisol?

Like most other things in our lives, moderation is key with cortisol and too much or too little are problematic. Our bodies are affected differently from temporary, acute rises in cortisol levels and chronically elevated levels.

  • Waking up in the morning. Cortisol is part of our bodies’ daily rhythm (circadian rhythm). Cortisol levels peak in the early morning and decrease through the afternoon and evening.
  • In people whose bodies can’t produce cortisol (a condition called Addison’s Disease) their bodies cannot mount a stress response and basically go into shock upon encountering a stressful event.
  • Cortisone, a synthetic form of cortisol, is used as a short-term drug to alleviate inflammation, swelling, and joint pain. Used too long, however, cortisone use can lead to memory problems, weight gain, depression, and increased infections.
  • Exercise increases cortisol levels temporarily (acute response), but this increase is actually beneficial to immune function, memory, appetite control, weight loss, libido, energy and inflammation. Workouts where the rest periods are short, total volume is high, and anaerobic metabolism is stimulated raise cortisol the most, and this hormone response is what’s most associated with muscle remodeling and growth.

What are the best options to combat elevated cortisol levels and chronic stress?

  • Awareness. Start taking note of occurrences in your life that raise your body’s stress levels.
  • Learn. Check out The Cortisol Connection, an awesome book. It’s an easy read and teaches about stress, cortisol, and effective ways to counteract the damaging effects of cortisol and stress. Empower yourself: Learn about your body.
  • Exercise! Regular exercise does so much to alleviate stress (mental and physical) and lower cortisol levels.
  • Prioritize Sleep.
  • Balance exposure to stress with recovery from stress. Plan your recovery days in addition to your workout days. Also, consider avoiding one cortisol trigger if you’ve encountered a lot of other triggers in that day.
  • Eat Well! Eating poorly, irregularly, or excessively actually adds stress to our bodies. Eating foods we have intolerances to increases inflammation which elevates cortisol and stress as well.


What are the most effective methods you know or use to reduce stress levels?

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Badrick, E., Bobak, M., Britton, A., et al.. The Relationship between Alcohol Consumption and Cortisol Secretion in an Aging Cohort. J Clin Endocrine Metab. 2008 Mar; 93 (3): 750-757.