The Hollow Leg and the Hypothalamus

By David L. Katz, MD, MPH, FACPM, FACP

There is a particular ‘Thanksgiving moment’ that occurs as the meal winds down. I set down my fork, groan, and say something like: “My goodness, I couldn’t eat another bite!” This, of course, is promptly followed by: “What’s for dessert?” Is that just me? I don’t think so.

Conventional wisdom holds that we have a hollow leg and/or an extra stomach on standby for just such occasions. It’s the hollow leg that makes room for dessert. This bit of folklore is, of course, utter nonsense. During my anatomy course all those years ago in medical school, I went looking for that hollow leg or extra stomach, and couldn’t find either one. I have conferred with colleagues, and they haven’t found them either.

Reasons Why We Keep Eating
When We Are Already Full

But anatomy does, in fact, hold an answer to this mystery – just not in mythical organs. The answer resides well above stomach or leg, namely in a part of the brain called the hypothalamus. The appetite center lives there.

There is a large body of scientific research indicating that our appetite center responds in a taste-specific and, to some extent, texture-specific manner. We crave salty and savory food up to a point, but then the ‘appetite meter’ for that particular category registers full. But not so the ‘sweet meter,’ which still may be registering empty. So, offer your taste buds dessert, and a whole new source of appetite turns on – and doesn’t turn off until that meter is also filled.

The tendency to fill up in a flavor-specific manner is called “sensory specific satiety.” I have addressed this in several of my books, and devoted one entirely to the topic.

That nutrition experts at big food companies know about sensory specific satiety is established fact. That they use it in product development to maximize the number of calories it takes for us to feel full is informed speculation on my part – but I’m quite convinced.

We are surrounded by the enticements of all-we-can-eat buffets. But even more pervasive, and far more insidious, is the goad of variety engineered into individual foods. In virtually every supermarket in the country you will find salad dressings and pasta sauces with a higher concentration of added sugar than is found in many desserts. By hiding ‘sweet’ in foods that are salty and savory, more appetite is turned on – and we eat more. I suspect someone laughs about this on the way to the bank.

Similarly, walk the cereal aisle of any grocery store, and you will see a whole array of popular breakfast items more concentrated in added salt than many (even most) of the items in the salty snack aisle. Few of us would think to sprinkle salt over our breakfast cereal, but the food industry has done it for us – and for evidently good reason.

This may all sound a bit ominous, but there is a bright side to this dark tale. The process can be reverse-engineered.

Since variety can stimulate an excess of appetite, simply controlling variety can reduce the number of calories it takes to feel full. There are pasta sauces and salad dressings without added sugar. They taste fine and are far less likely to put our hypothalamus into overdrive. There are breakfast cereals with less added salt.

I have long seen the benefits among my patients of trading up to ‘better’ choices within any given food category, choices that don’t have stealth additions of sugar, salt, or artificial flavor enhancers. There are benefits to health in general, but salient among them is this: When food is simpler and closer to nature, it fills us up on fewer calories. The beauty in this formula is that it allows for improving health and weight without being hungry all the time. With NuVal (www.nuval.com) now reaching some 30 million shoppers around the country, I have also heard many tales about people losing weight without feeling hungry by trading up their groceries.

I recommend indulging ourselves as the holidays warrant. We can be thankful that where feast meets hypothalamus, there’s a bit of extra room for the delicious fare the fortunate among us will enjoy.

By renouncing the myth of the hollow leg, and knowing something about your hypothalamus, you have new means to control your intake of calories without going hungry. Ideally, that will give you something new to be thankful for all year round. I genuinely believe we can love food – both the quality and quantity – that loves us back.

I wish you and your hypothalamus a wonderful holiday season!

David L. Katz, MD, MPH, FACPM, FACP is the founding director of Yale University’s Prevention Research Center. He is a board certified specialist in both Internal Medicine and Preventive Medicine/Public Health. He is the director and founder of the Integrative Medicine Center at Griffin Hospital in Derby, CT. For more information visit http://www.davidkatzmd.com and http://www.turnthetidefoundation.org

The articles written by guest contributors are the sole responsibility of the individual writers in terms of factual accuracy and opinion and do not necessarily reflect the views of the publisher of this blog.

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