Do Blood Glucose Levels Deport On Hunger Too Satiety?

You've heard the story before: when you lot swallow carbohydrate-rich foods that digest quickly, it sends your blood refined saccharify together with insulin levels soaring, so your blood refined saccharify grade comes crashing dorsum downward together with you lot experience hungry together with cranky.  You accomplish for to a greater extent than carbohydrate, perpetuating the wheel of crashes, overeating, together with fatty gain.

It sounds pretty reasonable-- inward fact, so reasonable that it's commonly stated every bit fact inward pop media together with inward casual conversation.  This sentiment is so deeply ingrained inward the pop head that people often enjoin "I convey depression blood sugar" instead of "I'm hungry" or "I'm tired".  But this hypothesis has a big problem: despite extensive research, it hasn't been clearly supported.  I've written well-nigh this number earlier (1).

Influenza A virus subtype H5N1 novel study offers a straightforward examination of the hypothesis, together with in i lawsuit once again finds it lacking.

The study

Bernd Schultes together with colleagues used a clever pattern to isolate the outcome of blood glucose on appetite (2).  They recruited fifteen salubrious immature men, together with on 2 occasions fed them an identical lite breakfast.

On i occasion, they waited i hr after the repast together with infused saline containing l grams of glucose into the volunteers' bloodstream over a one-hour period.  On the other occasion, they did the same affair except using saline without glucose.  Throughout the infusion, together with i hr afterward, the researchers monitored levels of blood glucose, blood insulin, together with markers of appetite.

The results

As expected, the glucose infusion markedly increased blood glucose together with insulin levels inward the hr next the meal.  After the researchers stopped the glucose infusion, the volunteers' blood glucose levels declined, eventually reaching a grade significantly lower than the command status (54 mg/dL vs lxx mg/dL).  This is the post-meal "crash" that is supposed to trigger appetite.

Yet levels of hunger, appetite, satiety, together with fullness didn't differ betwixt groups at whatsoever time-- either during the infusion or afterward.

Discussion

We convey extensive prove that the encephalon pays attending to blood glucose levels, together with triggers appetite when it goes likewise depression every bit purpose of a suite of protective responses to keep blood glucose grade (this is called the "counterregulatory response").  However, the prove overall suggests that you lot convey to convey pretty serious hypoglycemia for this to happen-- something that rarely occurs inward people who aren't using insulin to process diabetes.  When researchers truly stair out the blood glucose grade of non-diabetic people who study feeling "hypoglycemic", a modest percent of them truly are hypoglycemic, but the vast bulk convey perfectly normal blood glucose levels (3, 4, 5, 6).  Hypoglycemia is non something that occurs oftentimes inward the full general non-diabetic population, together with it doesn't offering a compelling explanation for why nosotros experience hungry or tired betwixt meals.

The encephalon listens to a diverseness of signals that signal the body's give away energy status, together with it integrates these signals to decide your sensation of hunger or satiety (7).  Glucose is i of the signals the encephalon listens to, but in that place are many others, together with the encephalon doesn't appear to pay really much attending to the glucose signal when it's inside the arrive at that occurs inward the daily life of most people.  In contrast, the encephalon pays attending to levels of leptin, CCK, GLP-1, glucagon, amylin, ghrelin, together with signals ascending from the gut via the vagus nervus (7).

I similar this study because it manipulated blood glucose levels inward a fashion that's non probable to hold out confounded yesteryear variables that bedevil other study designs.  They pulled this off yesteryear straight manipulating blood glucose, mimicking the glucose profile of a high-glycemic repast to run across if post-meal fluctuations at the extreme halt of the normal arrive at touching on appetite.

And, consistent alongside most previous research, it looks similar they don't.  How create nosotros reconcile this alongside the fact that some single-meal studies convey establish that lower-glycemic meals are to a greater extent than sating than higher-glycemic meals (8)?  Here's what I think.  The sating outcome of low-glycemic meals in all likelihood doesn't convey much to create alongside blood glucose at all, but rather: 1) the fact that these studies are normally non properly controlled for other variables known to touching on satiety, such every bit calorie density, fiber, protein, together with palatability; together with 2) the fact that lower-glycemic foods digest to a greater extent than piece of cake together with so tend to exit refined saccharify hanging to a greater extent than or less inward the gut interacting alongside intestinal satiety receptors for longer.

The authors conclude:

These findings clearly utter against the notion that fluctuations inward glycemia together with also insulinemia stand upwards for major signals inward the short-term rule of hunger together with satiety.

Bariatric Dr. Arya Sharma also had some proficient thoughts on this study (9):

The lesson here, I approximate is that, only because in that place is a seemingly compelling narrative to back upwards an idea, it does non hateful that that’s how biological scientific discipline inward existent life truly works.

I agree!