How Blood Sugar (Glucose) Affects Insulin, Hunger, Weight Gain, and Energy Levels
In a normal healthy human, in general, factoring out other complexities like other food and drink eaten with a meal:
Carbohydrates (especially simple ones like sugars) “spike” blood sugar (glucose) levels. This triggers insulin production causes hunger, and primes the body for weight gain. It also creates a quick energy spike followed by a quick crash. This is perfect for storing calories from fruit sugars in the wild, but not so great for modern snacking habits, weight gain, and the munchies.
This can be offset by eating fiber, protein, and a generally balanced diet, and can differ in those with medical problems, but, in simple terms, the general rule of thumb for a normal healthy adult would be:
Sugar can give you the munchies and cause weight gain. It does little to relieve your hunger pangs.
The two videos below explain how sugar “spikes insulin” and causes weight gain. See below for further science and insight.
The Skinny on Obesity (Ep. 3): Hunger and Hormones- A Vicious Cycle. This video also describes leptin which is a hormone that helps suppress hunger. It sends a message from your fat cells to your brain to tell your brain you are full, insulin suppresses leptin.
The Skinny on Obesity (Ep. 4): Sugar – A Sweet Addiction. This video describes other effects of sugar.
FACT: For the average person controlling weight may be a matter of determination. However, there are many additional considerations depending on a range of health factors. For instance, some genetic conditions such as Prader-Willi syndrome impact appetite so strongly that individuals with it can eat themselves to death, will consume rotted, raw, or frozen food, and will never feel satiated. People with Prader-Willi need all their food to be locked away and dispensed for nutrition. Some hormonal conditions such as thyroid imbalances act much the same way. Also, some body types are better at storing fat, and some are better at using fat stored in fat cells. Your body type, hormone levels, metabolism, genetics, and other health factors can make weight loss harder for some, and easier for others.
TIP: The only cure for the munchies, aside from eating way too much, is time, although drinking water helps. People fall into the trap of eating sweets or simple carb-based treats, only to trigger hormones that make them more hungry, only to eat more sweets, instead of eating nutrient and amino dense foods that would have satiated their appetites and avoided insulin production.
The Relationship Between Insulin, Glucagon, Glucose, and Weight Gain
The relationship between insulin, glucose, and weight gain works like this:
- When we eat, our bodies convert simple and complex carbohydrates (and parts of fats and sometimes proteins) into blood sugar. Everything else in food is amino acids (energy from protein), fatty acids (energy from fat), vitamins, minerals, and a few compounds like cholesterol.
- The technical term for blood sugar is Glucose. So high glucose levels mean high blood sugar levels. The terms are synonymous in food science. They refer to the sugar in the blood, not the blood.
- Glucose is the main source of energy for our bodies, but in order to store glucose, we need insulin.
- Insulin, and its counterpart Glucagon are hormones made by islet cells in the pancreas that allows our bodies to use glucose as energy or to store glucose for future use (as fat, or in the muscles and liver).
- Insulin, which is produced when blood sugar is high, tells our fat cells to store energy and not to use energy and tells our bodies to feel hungry and not to feel full (good for weight gain).
- Glucagon, which is produced when blood sugar is low, tells our bodies to release stored glucose (including glucose stored in fat cells) to raise our blood sugar (good for weight loss).
- Thus, insulin and glucagon help regulate our blood sugar, meaning they help keep our blood sugar levels from getting too high (hyperglycemia) or too low (hypoglycemia).
- Low glucose levels (“low blood sugar”) cause us to feel “low energy,” cause our mental functions to slow, and cause our bodies produce less insulin and more glucagon.
- High glucose levels “spike our insulin” levels and temporarily raises our hunger, raises our energy levels, and increases our ability to store fat. When this happens are bodies also produce less glucagon (so energy is stored, not used).
- Not only does insulin raise our hunger, but it also suppresses leptins, a hormone that makes us feel satiated (makes us feel full; not hungry).
- When glucose and insulin levels subside after a “spike,” it causes a “sugar crash,” which makes us feel low energy. See “What Is A Sugar Crash?“
- Thus we can say, high levels of glucose taken into our system (for any reason) too quickly causes hunger, suppresses satiation, mucks with energy levels, can affect mood, and signals the body to store fat.
Insulin, Glucose and you.
TIP: See our page on science-based weight loss and diet advice.
TIP: Diabetes is when people have problems producing insulin, those they have issues with both low and high blood sugar. Learn more about “What Does Insulin Do?“.
TIP: Glucose is a catch-all term for different types of simple carbohydrates (sugars) that our bodies need to function, its the type that gets stored in fat (and used for most bodily functions that require energy, along with the amino and fatty acids). Another important term is glycogen. Glycogen is a type of glucose that is a complex carbohydrate and starch made of several glucose molecules and is stored in the muscles and liver; it’s the type that is used for temporary energy. Our main focus is not the relationship between glucose and insulin; all glucose and acid types are important in terms of how our bodies use energy. See Glycogen vs. Glucose by LEXA W. LEE.
TIP: There is an energy store in the liver which is temporary and doesn’t affect weight gain (the muscles can perform a similar function too). The trick to not gaining too much fat is to avoid overeating and to avoid spiking blood sugar. Keeping glucose levels stable results in you using the energy stored in the liver instead of gaining fat cells, but some amount of fat storage will occur in the human diet.
How and Why “Insulin Spikes” Cause the Munchies
When insulin spikes as a result of increased glucose levels, it sends your body into “munchy mode.” This is not a technical term. It describes the state in which hormones suppress satiation and incite hunger; we call it “the munchies.”
Munchy mode is perfect for roaming in the wild and coming across an apple tree. You get a quick spike of energy, your hunger increases, you don’t feel full when you eat too much, and your body becomes extra good at storing all that fruit sugar as fat so you don’t have to find another food source for a while.
The problem is, we don’t live in the wild, and we are more likely to experience munchy mode on the couch with a big bag of candy than in a situation that requires us to store a bunch of simple carbs quickly.
Why You Got Fat. As this video notes weight gain related to insulin is one-half your body getting the signal to store fat and one-half your body successfully knowing how to use energy stored in fat cells. Some people are unlucky in that they store energy in fat easily but have trouble using that energy (making weight gain easy and weight loss hard). This condition is called “insulin resistance.”
How to Prevent Against Insulin Spikes and Weight Gain
The simplest way to prevent insulin spikes for a normal healthy adult is to limit or avoid simple sugars and simple carbs, which means avoiding processed foods and table sugars.
All simple and complex carbohydrates including soluble fiber are turned into glucose; proteins and fats can be too. However, it takes your body a lot of work to process the more complex macronutrients, and that helps regulate blood sugar and insulin levels.
So, of course, the straightforward advice is: eat healthy foods. The slightly more complex advice is to always eat a balance of macronutrients. A healthy diet avoids too many simple sugars being synthesized too quickly while making sure you get all the essential acids and micronutrients.
Sugar: The Bitter Truth.