For the purpose of this book and to decrease confusion, I am over-simplifying a complex process. In a way, ghrelin and leptin act in opposition to each other for the body to maintain ideal energy balance or ideal body weight.15,19,26 But being the complicated humans that we are, this system has many loopholes.16,27-28
The incinerator, your stomach, can only burn and process so much food at a time. OF COURSE, you can override or trick the closing door of the incinerator. This happens when you eat super fast, like in less than 5 minutes, and you eat enough to feed a family of four without even realizing what you are doing. And THEN the door closes 20 minutes later. Remember, I said it closes very slowly.
When you eat that quickly, you’ve tried to pack in much more food than the incinerator can actually handle. We’ve all done it and felt that, “Oooohhhhh, I feel so full; I went way too far” feeling. Why didn’t your body tell you? Probably because you raced against the door and WON!!! Even if you aren’t eating fast, you are a human with a smart brain. You can override, trick or ignore the system any time you want.
The human body has the capacity to eat way more than it can burn. And it has a compensation mechanism for every time you eat more than you can burn. It’s a kind of storage channel to account for overeating — it’s called fat storage.29 You can eat more than the body needs before the door closes or you can ignore that the door has closed and keep eating.30-31
Ideally, we would all stop when we feel full, regardless of what we are eating. However, for lots of reasons, we keep eating, and eating and eating overriding the ghrelin/leptin system. We can continue to eat long after the door has closed. At this point your body says, “What am I going to do with this excess? I didn’t need all this food and can only handle so much at one time. I guess I’ll just use that compensation mechanism and store it for later.” The incinerator does not change its capacity.32
When you eat on a “closed-door” incinerator, you have much more potential to store the extra food as fat. This is true of all foods whether it is a carbohydrate, protein or fat.33 The incinerator cannot burn food sitting outside the closed door. The same thing happens when you eat when you aren’t hungry, when the incinerator door didn’t open. It is as if the food sits on top of a closed door, waiting to be stored. When it sits outside of a closed door, it has more potential to be stored as fat rather than wait around until the door opens again.16,27-28
Unless something has gone metabolically29 or genetically wrong, all humans are equipped with the mechanisms to signal hunger and fullness. However, there are conditions and circumstances that mask these mechanisms. Some of these reasons include eating disorders, diseases, medications, mood and our environment.13,34
13. Murray M, Vickers Z. Consumer views of hunger and fullness. A qualitative approach. Appetite. 2009;53(2):174-182.
15. Moehlecke M, Canani L, Silva L, Trindade M, Friedman R, Leitão C. Determinants of body weight regulation in humans. Arch Endocrinol Metab. 2016;60(2):152-162.
16. Carson E. Pleasure overrides fullness when it comes to controlling food intake. SCAN’s Pulse. 2016; 35(4):1-2.
19. Power M, Schulkin J. Anticipatory physiological regulation in feeding biology: Cephalic phase responses. Appetite. 2008;50(2-3):194-206.
26. Gropper S, Smith J, Groff J. Advanced Nutrition and Human Metabolism. 5th ed. Belmont, CA: Wadsworth; 2005: 299-300.
27. Perello M, Sakata I, Birnbaum S et al. Ghrelin Increases the Rewarding Value of High-Fat Diet in an Orexin-Dependent Manner. Biol Psychiatry. 2010;67(9):880-886.
28. Goldstone A, Prechtl C, Scholtz S et al. Ghrelin mimics fasting to enhance human hedonic, orbitofrontal cortex, and hippocampal responses to food. Am J Clin Nutr. 2014;99(6):1319-1330.
29. Gropper S, Smith J, Groff J. Advanced Nutrition and Human Metabolism. 5th ed. Belmont, CA: Wadsworth; 2005: 167-168.
30. MacDonald A. Why eating slowly may help you feel full faster. Harvard Health Publishing website.
31. Kokkinos A, le Roux C, Alexiadou K et al. Eating Slowly Increases the Postprandial Response of the Anorexigenic Gut Hormones, Peptide YY and Glucagon-Like Peptide-1. J Clin Endocrinol Metab. 2010;95(1):333-337.
32. Stroebe W, van Koningsbruggen G, Papies E, Aarts H. Why most dieters fail but some succeed: A goal conflict model of eating behavior. Psychol Rev. 2013;120(1):110-138.
33. Gropper S, Smith J, Groff J. Advanced Nutrition and Human Metabolism. 5th ed. Belmont, CA: Wadsworth; 2005: 251-254.
34. Berridge K. ‘Liking’ and ‘wanting’ food rewards: Brain substrates and roles in eating disorders. Physiol Behav. 2009;97(5):537-550.