Written By: Kevin Cann
As the obesity epidemic continues to get worse, researchers are frantically attempting to find out what the major causes of obesity are and to develop treatment protocols to reverse it. We know that nutritional intervention mixed with physical activity is our greatest weapon against this epidemic.
For decades we have attempted to deliberately cut calories to lose weight and we have failed miserably. In order to develop a plan to achieve sustainable weight loss we need a better understanding of what truly drives our appetite.
We have hormones that both stimulate and suppress our appetite. The only known orexigenic hormone (appetite stimulating) is ghrelin. Leptin does not actually stimulate appetite but controls ghrelin’s orexigenic effect. On the other side of the coin are our anorexigenic hormones (appetite suppressant). The list of known anorexigenic hormones is; including cholecystokinin (CCK), pancreatic polypeptide (PP), peptide YY (PYY), glucagon-like peptide (GLP)-1, and oxyntomodulin (OXM). This group of hormones is known as our gut hormones.
The one gut hormone I would like to discuss today is cholecystokinin (CCK). CCK was the first gut hormone identified to control appetite in humans. Studies have shown CCK to decrease food intake in both lean and obese people (1). Within 15 minutes of eating our plasma levels of CCK rise.
Once CCK is released it stimulates the gallbladder to release bile, the pancreas to release enzymes, and inhibits gastric emptying. On top of its role in digestion, CCK travels to the hypothalamus. This is important because the hypothalamus is the area of the brain responsible for appetite control. Here in the brain it acts as a neurotransmitter and neuromodulator. There are four main areas where CCK is hypothesized to play a role within our brain.
CCK interacts directly with dopamine, our neurotransmitter responsible for memory, focus, energy, and our reward response. CCK may play an integral role in the development of panic attacks. CCK may aid the opioids in identifying harm within the body. Lastly, CCK plays a role in satiety (2).
This versatile and important gut hormone may be one of the major reasons that food can induce panic attacks and anxiety. When CCK is not functioning properly it may be a major player in our abilities to overeat. When developing a weight loss plan in mind we need to look at all the areas that may negatively affect CCK’s ability to its job.
One of the major culprits negatively affecting CCK is wheat. A protein in wheat known as wheat germ agglutinin (WGA) inhibits the binding of CCK to receptors. The negative effects of WGA on CCK were found in doses greater then 1microg/mL and the EC50 (the dose responsible for a response halfway between baseline and maximum) was 8microg/mL and at 25 microg/mL CCK’s ability to bind to receptors was reduced by 70% (3).
The negative effects that wheat has on CCK may be one mechanism in which wheat consumption influences memory, energy, opioid interactions, and can make it easy to overeat. The other area of concern is in the digestion of fat and other nutrients. Remember CCK plays a role in stimulating the gallbladder to release bile and the pancreas to release digestive enzymes. If CCK is not doing its job we will not digest fats properly, which means we will not be absorbing our crucial fat soluble nutrients such as vitamin A, D, E, and K.
Soy has been shown to increase CCK production (4). This initially may sound like a good thing, but in science too much or too little of anything is not good. Increased CCK production without inhibition can lead to pancreatic and stomach growth. A constant influx of CCK can also lead to the receptors becoming desensitized and our body needing to release more CCK to get the desired outcome. Research has shown over the last 20 years that CCK may play a role in the development of certain cancers (5).
Interestingly enough soy has been linked to pancreatic cancer. In a study that fed rats raw soy flour for a year, 10% of them developed pancreatic cancer (6). Other dietary sources of lectins such as peanut lectin have been shown to have similar effects on CCK production (7).
CCK also plays a role in our gut health by stimulating gut mucosal growth (8). We need to give our gut the nutrients it needs to heal itself and the nutrients it needs to thrive. This comes from eating plentiful amounts of fruits and vegetables.
Protein from quality sources such as meat, fish, and eggs are also important. Protein has been shown to be the most satiating macronutrient. One reason for this is its effect on CCK production (9). At the same time we are including foods that will nourish our gut; we need to remove the potentially hazardous ones.
Foods such as grains, legumes, and dairy can be gut irritating for the majority of us. I know there has been lots of debate on this topic lately, but there is no risk to removing them from your diet and a potential high reward. Try removing them from your diet for 30 days and bring them back one by one and see how you feel.
Foods that are causing an inflammation response can negatively affect both leptin and CCK. Leptin and CCK work together to provide an anti-inflammatory action in our gastrointestinal tract (10). With any hormone, if we have too much of it released, the receptor sites will desensitize to it and we will need more of the hormone to do its job.
This means if we are eating inflammatory foods frequently we could have enough CCK in the system, but due to CCK resistance, the inability to bind to the receptor sites. This leaves excess CCK floating around and may increase our risk for certain gastrointestinal cancers as well as our hypothalamus not receiving the message to stop eating.
The gut healing properties and the ability of the paleo diet to restore function in our energy homeostatic hormones are the major reasons why it is so successful for weight loss. This allows us to take in fewer calories and to tap into our fat stores more easily. The more I read and research the more it solidifies the paleo diet in my eyes as being the optimal human dietary template.