Myth: Insulin Makes You Hungry

10 May

With all the conflicting information available on the web, it can be difficult to apply even the most sound dietary concepts to your lifestyle.  As a member of the Eat To Perform Science Lab, you’ll communicate with experts in the fields of nutrition, exercise physiology, and strength and conditioning, as well as hundreds of other members who’ve found themselves on a similar path. 
 

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We’re hearing from a lot of people who believe that when blood insulin levels go up in response to a carbohydrate-dense meal, you wind up hungrier than you were before you ate.  This couldn’t be further from the truth.   Insulin does not cause hunger.  Ghrelin, “the hunger hormone,” is produced during periods of low blood sugar, when growth hormone levels are elevated and insulin levels are at their lowest (4).   The hormone leptin inhibits the action of ghrelin and tells your brain that you’re full, and glucose metabolism is the primary determinant of leptin secretion in humans (3).

Furthermore, a recent study by Wellhoener et al.,  has shown that the administration of insulin after feeding curbs appetite.    However, it did not have any  effect on satiety during fasting when blood sugar  was low (2).  These data support the idea that insulin can help control hunger.

In short, carbohydrate metabolism makes you feel happy and full (5).

While insulin may play a small role in keeping you from overeating, its job is to open up a channel to transport nutrients into cells.  The video below by Dr. Bryan Walsh explains what insulin is, and how it works, better than anything else on the internet, so you should definitely give it a watch:

So Why the Confusion?

One of the problems with this whole scenario is that it only works like that when your body is functioning properly and you’re making the right lifestyle decisions.  Leptin resistance will confound issues with hunger and make it difficult to lose body fat.  Even when you eat an abundance of carbs, your brain won’t get the signal that you don’t need to eat any more.  You’ll never feel full and you’ll always be on the hunt for a sugary snack.  If you’re insulin resistant, you’ll have a difficult time utilizing glucose, no matter how much insulin you produce.  What would normally energize you and satisfy your hunger will ultimately make you sick, as glucose is toxic in the blood stream.

The second problem is that of the blood sugar “crash”.  When blood sugar levels rise, insulin springs into action to help cells soak up the glucose.  Foods that produce a high glycemic load will elicit an insulin “spike” that will rapidly clear glucose from the blood stream (granted the person is insulin sensitive.)  The sudden drop in blood sugar results in a crash that will knock you on your butt.  For this reason, many people suggest that you avoid high glycemic index carbohydrates (rice, potatoes, etc.) but these are some of the best foods for replenishing glycogen.

How to Make Carbs Work for You

First of all, you need to engage in high intensity, anaerobic exercise.  Second, you should eat mostly fat and protein during the day, and stick to fibrous carbohydrate sources that won’t spike your insulin.  Eat starchy, high GI carbs after training, when your muscles will be most sensitive to glucose uptake, and include a healthy amount of fat in your evening meals to get a more stable blood sugar response while you get ready to go to sleep.  Over time, your cells will become more flexible and your metabolism will begin to function properly.  When you dial in your approach, hunger and lethargy will become a thing of the past.

Mike’s Notes

Just how insulin itself works is a confusing mess, but my bias is that if your body is running primarily on carbs, a smaller drop in carbs will probably signal your body to consume more carbs.

If you can more effectively use fat, you could argue that instead of triggering hunger, your body would shift to use fat (become more metabolically flexible).

This dates back to the research some 50 years ago called the “Glucostatic Theory of Appetite Control” (6).

Summary:

  • Many people experience hunger after a high carb meal.  They wrongly blame insulin and carbohydrate consumption for their hunger.
  • In reality, carbohydrate consumption increases the amount of leptin circulating in your blood stream.  Leptin is the “I’m full” hormone.
  • Insulin doesn’t make you hungry; it actually makes you feel satisfied.
  • Ghrelin is responsible for signaling hunger, and it rises during periods of low insulin.
  • Most of the confusion arises when people eat high glycemic carbohydrates like rice and potatoes that generate a strong insulin response and possibly lead to a blood sugar crash.
  • Chronically elevated levels of blood sugar, which render you insulin/leptin resistant, screw up your hunger signaling all together.  This makes it hard to lose fat and regulate your blood sugar/feeding patterns.
  • You can avoid most of these problems by engaging in high intensity activity on a regular basis, eating carbs around training, and eating mixed meals of fat, carbohydrate, and protein to regulate absorption.

Works Cited

1)      Katsuya Dezaki, H. S. (2008, May). Ghrelin is a physiological regulator of insulin release in pancreatic islets and glucose homeostasis.

2) Manfred Hallschmid, S. H. (2012, February 16). Postprandial Administration of Intranasal Insulin Intensifies Satiety and Reduces Intake of Palatable Snacks in Women.

3) Peter Wellhoener, B. F.-S. (2000, March 1). Glucose Metabolism Rather Than Insulin Is a Main Determinant of Leptin Secretion in Humans.

4) Tomomi Shiiya, M. N.-I. (2002, January 1). Plasma Ghrelin Levels in Lean and Obese Humans and the Effect of Glucose on Ghrelin Secretion.

5) Woodend, G. H. (2003, October). Consumption of sugars and the regulation of short-term satiety and food intake.

6)  Mayer, J. (2009, January). The glucostatic theory of appetite control and the risk of obesity and diabetes.

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