Diet Tips from Snakes? The Evolution of "Not Feeling Hungry": Disappearance of Hunger Hormones Suggests an Alternative Metabolic Pathway

Diet Tips from Snakes? The Evolution of "Not Feeling Hungry": Disappearance of Hunger Hormones Suggests an Alternative Metabolic Pathway

1. Why the "Apex Predator" Doesn't Need to Eat So Much

Swallowing deer whole and sometimes even attacking crocodiles—snakes have a flamboyant way of eating. But what's truly surprising is what happens next. Many snakes can go weeks, months, or even nearly a year between meals, depending on conditions. From a mammalian perspective, this is an almost superhuman (or super-reptilian?) fasting endurance.


This "talent for not eating" might be explained not just by muscle mass or behavioral strategies but by a more fundamental "blueprint." This topic was brought to light by a study that broadly compared the genomes (entire genetic information) of reptiles.


2. The Key is the "Hunger Alarm"—Loss of the Ghrelin Gene

The research team focused on a hormone called ghrelin, commonly known as the "hunger hormone," which is involved in regulating appetite and energy use. The report suggests that the ghrelin gene (GHRL) in snakes has been lost or "degraded" to a form that is less functional.


Furthermore, the enzyme MBOAT4, crucial for activating ghrelin (acting like a "switch" for ghrelin), is similarly lost or degraded in snakes. In other words, the "hormone that signals hunger" and the "mechanism that activates it" have both weakened.


The analysis wasn't limited to snakes. In a genomic comparison of 112 species, including snakes, lizards, turtles, and crocodiles, similar losses were independently observed in chameleons and some lizards. This is significant because if it were merely a "random breakage," it would be unnatural for the same loss to occur repeatedly across different lineages. The research team views this as an adaptation selected through the course of evolution.


3. "Sit-and-Wait" Lifestyle and the Compatibility Issue with Hunger Hormones

Many snakes and chameleons excel at "sit-and-wait" predation, where they hide and wait for opportunities rather than expending calories chasing prey. This is a rational strategy, but the waiting period can be long. Sometimes they remain motionless for weeks or even months.


The tricky part here is the "hunger alarm." What happens if the hunger signal keeps ringing inside the body? The temptation to move might increase, making it harder to continue waiting calmly, and it could also lead to constant stress responses or metabolic activation. For predators that grow stronger the longer they wait, a "mechanism that strongly feels hunger" could be more of a hindrance.


This study suggests that the reason snakes can endure extreme fasting is not simply because they are "patient," but because they may have shifted towards a design that **"doesn't strongly activate hunger in the first place."**


4. Different Energy-Saving Methods—Not "Burn Fat" but "Don't Burn"

What's even more interesting is the role ghrelin plays in mammals. Generally, during fasting, the body is guided to burn fat for energy. However, snakes seem to have chosen a different method for the same "fasting."


The main point of the research is this: In snakes, the weakening of the ghrelin system may have reduced the need to aggressively oxidize fatty acids in muscles during fasting, making it easier to enter an **extreme energy-saving state (low-consumption mode).** In other words, while mammals "keep the fuel running to get through," snakes "turn off the engine and endure." The strategy differs even with the same fasting.


Of course, snakes don't completely avoid using fat. However, if optimized for a sit-and-wait lifestyle, "waiting with low fuel consumption" rather than "moving anxiously due to hunger" might increase success rates. The bold change of losing genes may have supported this direction.


5. Meaning for Humans: Not a "Diet Answer," but a Metabolic Insight

"If there's no hunger hormone, humans should eliminate it too!"—such simplistic thoughts might arise after hearing this. However, the research points not to a simple blueprint for weight-loss drugs but to the existence of an "alternative metabolic route.".


Like snakes, maintaining muscles and organs during long-term fasting while switching to rapid digestion, absorption, and growth when necessary (snakes also undergo dynamic organ changes after eating). If the loss of the ghrelin system is part of what enables this switching, it challenges the view of obesity and metabolic disorders as merely "appetite problems."


In other words, suppressing hunger ≠ the correct answer; rather, there are points to learn from the very design of energy distribution. The research team also mentions the potential for such extreme energy control to provide insights into medicine.


6. Reactions Seen on Social Media (Within Publicly Visible Range)

This topic was not only spread as a news article but also introduced on social media through official account posts. Within the publicly visible range, the following types of reactions stand out.

  • "Envious of a body that doesn't feel hunger" type
    The key point of the article (loss of hunger hormone-related genes) easily becomes a trigger for envious comments. Especially in the context of dieting, questions like "Can't this be applied to humans?" are likely to arise.

  • "Optimized for sit-and-wait lifestyle, evolution is amazing" type
    The explanation linking predation strategy (sit-and-wait) and gene loss is intuitive, and there's a sense of "ecology and genome connecting as one." This often elicits reactions filled with a sense of romance.

  • "So do snakes live with zero hunger?" misunderstanding critique type
    There's a tendency to oversimplify "no gene = no hunger at all," so calm clarifications like "They must be adjusting through other pathways" or "Hormones have multiple systems" are common.

  • Specialized reactions: Attention to 'independent loss in multiple lineages'
    The point that similar losses were shown in species other than snakes in the 112-species comparison is compelling from the perspective of evolutionary repeatability. It connects to a deeper discussion beyond just "snakes are amazing."


7. Points of Interest Moving Forward

This study doesn't simply conclude with "snakes can fast because they lack the ghrelin gene." Rather, the next focus is on how "weakening the hunger signal," "waiting with energy conservation," and "explosively increasing metabolism after meals" are integrated.


And if similar losses have independently occurred in snakes, chameleons, and some lizards, there might be an "obvious optimal solution" that evolution repeatedly arrives at for enabling extreme fasting. While it may not be a direct shortcut to human health research, it's sufficiently intriguing as a hint for expanding the map of metabolism.


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