Why We Eat the Way We Do - The Science of Appetite
5 billion pounds.
That’s the estimated collective amount Americans are overweight.
Recently, there was an interesting Time magazine cover story that discussed the science of appetite and asked:
Just why is our appetite so powerful a driver of our behavior, and, more important, how can we bring it to heel?
These are difficult questions to answer, as there are many factors that can influence appetite, including “taste, smell, sight, texture, brain chemistry, gut chemistry, metabolism and, most confounding of all, psychology.”
The article discusses several of these factors in more depth, including how:
We’re programmed to eat to excess to store energy.
“We were hardwired to eat and eat—and particularly eat fatty foods because we didn’t get them often,” says Sharman Apt Russell, author of Hunger: An Unnatural History. We’re programmed not only to overeat but also to fail to recognize immediately just when we’ve reached that point. Mothers tell kids not to wolf their food because it’s harder to enjoy it that way and also because even after you’ve had enough, it can take a while for your brain to get the message. By the time it does, you’re not just full; you’re stuffed. “The people who didn’t immediately lose their appetites, who could gorge themselves and keep going, those people would survive longer during the next famine,” says Dr. Jeffrey Flier, obesity scientist and professor at Harvard Medical School.
The wide availability of inexpensive, high-calorie foods feeds directly into this historical tendency and contributes to a greater risk for obesity.
Hormones and peptides regulate hunger.
Both appetite-stimulating substances (e.g., the hormone ghrelin) and appetite-inhibiting substances (e.g., the peptide cholecystokinin (CCK) and the hormones leptin, GLP-1, and PYY) communicate with the brain to either increase or decrease hunger.
There are literally dozens of other hormones and peptides that may also play a role in controlling appetite.
The article discusses how researchers are taking many different approaches in an effort to influence this complex system, including studying:
- The individual receptor sites in the brain to which these hormones and peptides bond.
- Neurons in the brain’s hypothalamus that produce proteins in response to these substances.
- Cellular receptors called PPARs (peroxisome proliferator activated receptors) that help to regulate metabolism.
- How excessive eating mirrors drug addiction patterns.
Refer to the article for expanded discussion of each of these research areas.
What You Can Do
The last section of the article briefly discusses some of the approaches for controlling appetite that researchers are examining, including:
- Emphasizing low-glycemic index foods, which may help maintain more constant glucose and insulin levels, and, in turn, reduce cravings and the need to refuel as often.
- Combining appetite-inhibiting substances (e.g., leptin & CCK) in supplement form.
- Eating bigger portions of lower-calorie, nutrient-dense foods (vegetables and fruits).
An accompanying pictorial also provides some suggestions:
- Eat foods higher in fiber to stimulate appetite-suppressing hormones.
- Eat more slowly to allow appetite-suppressing time to be released and recognized by the brain.
- Eat at regular intervals to keep blood sugar and appetite hormone levels steady.
Given the complexity of the body’s appetite control system, it’s unlikely that a single magic approach or pill exists to reduce hunger and/or weight.
As discussed in this earlier post, there are also many other important factors that can influence the risk for obesity, including:
- Sleep debt
- Environmental toxins (that can disrupt hormone function)
- Temperature regulation
- And more …
Your best bet is a comprehensive approach that attempts to identify and address as many of the nutritional and other environmental factors that may be involved, rather than trying to find a silver-bullet.
You can find a good short-list of suggested steps at the end of this earlier post.
Other Stuff Worth Checking Out
The cover story is one of several interesting nutrition-related articles in the Time magazine issue.
For example, there’s an eye-opening photo gallery that includes photos by Peter Menzel from the book Hungry Planet. The photos show 15 different families from around the world surrounded by the food items that they each eat in a typical week. The differences are pretty amazing.
At the same time, as the accompanying article notes, the similarities are quickly growing — and health-wise, not necessarily for the better:
In an era of instant communication and accelerated trade, those cultural exchanges have exploded, leading to something closer to cultural homogenization. That’s bad for not only the preservation of national identities but the preservation of health too. Saturated fats and meats are displacing grains and fresh vegetables. Mealtimes are shrinking. McDonald’s is everywhere. From Chile to China, the risk of obesity, diabetes and heart disease is on the rise as the idiosyncratic fare that used to make mealtime in New Delhi, Buenos Aires and Sydney such distinctive experiences is vanishing.
Refer to this page for an easily accessed list of all the nutrition articles in the Time magazine issue.
Also, see the home page of my main website for a list of common conditions and how nutrition can play an important role in preventing and treating them.
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(Images: Time.com, Science)
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