Juvenon Health Journal 2014 – April 2014, No. 4
There is something deeply primal about feeling hungry. However, from biological and psychological standpoints, the cause of that gnawing feeling is anything but simple. Indeed, it is a puppet with many masters.
Hunger begins with pangs in the stomach, but eventually progresses into an all-encompassing sense of urgency driven by the psychology of mood and emotion. Ultimately, hunger — or at least the perception of hunger — is a basic driving mechanism that can be at the root of much trouble related to your metabolism. Weight control, hormonal balance, diabetes, cardiovascular and metabolic disease are just a few of the hunger driven problems that we face. Unfortunately, the media abounds with distorted and incorrect nutritional information that serves as a false foundation for a true understanding of hunger and satiety.
What’s Eating You?
The sensation of hunger is a basic survival mechanism whose stages are progressively regulated to advance from an early ‘feeling’ in the stomach to an eventual all-encompassing drive to obtain food. Although it begins with the stomach, hunger is actually managed by a complex system of neurological sensations that feature endocrine and hormonal signaling strung together and anchored by a strong network of behavior, habit and emotion. If we dissect the sensation of hunger along these lines, we can learn a lot.
Three Levels of Hunger Control
The original notion of hunger is based on the glucostatic theory. The premise behind this theory is that basically the body seeks to keep blood and tissue glucose levels static. Thus, when glucose is depleted to a certain level, the feeling of hunger is induced. But, scientists now understand that it’s not quite that simple. You see, we actually have three basic levels of regulation controlling our sense of hunger.
Circulating Fuel Status
Circulating fuel status gives the food-seeking portion of the brain information about the current availability of glucose as a fuel. A more current understanding of hunger and satiety shows us that the rate of glucose depletion we experience is a more correct driver of hunger than the level. This is generally managed via insulin secretion.
Stored Fat Fuel
Research shows that hunger is also strongly regulated by body fat fuel stores. Our body stores excess food energy as fat which can, in times of need, be readily accessed as a fuel source. Adipose, or fat cells, secrete a hormone called leptin that communicates to the brain relative information about how much fat is stored. In this way, hunger is regulated to maintain not only enough fuel for basic metabolism, but also fuel to maintain the continued storage fat. And this is the reason why being overweight can cause you to feel more hungry.
Finally, the stomach regulates hunger through satiety– the feeling of being full. When full, the stomach secretes a hormone called ghrelin, which acts on hunger centers in the brain to signal cessation of hunger.
The Sugar Trigger
Why is it that right after you eat that sweet desert, handful of dried fruit or heaping helping of mashed potatoes, your hunger rebounds with a vengeance?
This particular hunger surge is related specifically to the first mechanism of hunger regulation, which involves blood glucose and insulin. Eating carbohydrates causes blood glucose levels to rise. It’s best when these levels rise slowly as is the case with a complex carbohydrate source, as in whole grains and veggies. However, it rises quickly if it is from simple carbohydrates, such as sugary treats, white pasta, fruit or even yogurt.
Glucose has little use while in circulation in the blood. In fact, high blood glucose, or hyperglycemia, is toxic and dangerous if it’s too high for too long. As blood glucose levels rise, so does the risk of hyperglycemia. This in turn causes the insulin secretion to rise, signaling body cells to absorb glucose, removing it from circulation.
Simple carbohydrates deliver glucose very rapidly into the bloodstream resulting in a fast rise in insulin. Complex carbohydrates take longer to digest and absorb and thus result in slower insulin secretion. So, the rate of glucose rise is directly correlated to the rate of insulin-mediated glucose decline. Recall that the rate of glucose depletion we experience can be a primary driver of hunger. The more rapid spike up — and down — in blood glucose, the more likely we are to experience a false sense of hunger shortly after a meal.
Media and advertising suggest we should eat carbohydrate-rich meals often. They reason that this constant flow of carbohydrates is the best way to regulate your metabolism and prevent hypoglycemia, or low blood glucose. Truth is, unless you are diabetic this is exactly the opposite of what your body needs to properly regulate metabolism and hunger.
Complex carbohydrates are a suitable fuel for sustained physical work, endurance sports training or competition. For all other times, it would suit our metabolism and mitochondria best to avoid insulin spikes. The ill effects of chronically elevated insulin are directly correlated with the usual host of chronic health conditions, including diabetes, obesity and cardiovascular disease.
The Wisdom of Our Ancestors
The primal nutrition diet is not a modern fad. It is a fact of our modern existence that our ancestors lived and thrived on a diet primarily composed of vegetables, fat and protein. Carbohydrate sources were limited to vegetable starches and the occasional exposure to seasonal fruits, berries and foraged honey.
In this context it is easy to understand how our metabolism is tricked into false sensations of hunger. Now imagine what happens when an overweight person indulges in a mid-morning donut. This all too common scenario amounts to the perfect storm of hunger induction.
The take home message here is that unfortunately carbohydrates, especially alone and in the absence of exercise, will only make you hungrier. If you can’t give up your carb-rich diet, but want to stay healthy, then you’ll have to maintain an extremely active lifestyle featuring plenty of vigorous exercise to burn those excess carbs.
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