The Real Reasons We Overeat

A new book attempts to explain Americans' love of unhealthy foods. What it gets right--and what it misses.


Photo by Kai Hendry/Flickr CC

Few would take exception to the assertion that obesity is an enormous health problem in the United States. There is less agreement, however, on how to combat the problem. David Kessler's new book, The End of Overeating: Taking Control of the Insatiable American Appetite offers a compelling case that to prevent overeating--and hence obesity--people should avoid processed foods as well as many popular chain restaurants such as Olive Garden and Chili's. The advice is consistent with what many experts who treat or research obesity have been recommending, but not entirely for the same reason.

Many of us recommend avoiding fast food in particular, and eating out in general, because of the tremendous number of calories in many of the meals offered. Although some fast food restaurants, such as McDonalds, have recently started offering some healthier options, most of the menu items are high in fat and calories. A recent study found that the average lunchtime purchase from a fast food restaurant in New York City contained more than 800 calories--far more calories than most people should be eating at lunch.

To increase profits, Kessler argues, food companies want to develop foods that are so stimulating you crave them--or at least cannot resist them. Kessler does not suggest that these industries are hiding the health effects of their product, the way tobacco companies did. But the case he makes suggests that they are at least partially liable for the obesity epidemic. Kessler does a nice job of explaining that both human and animal studies have found that eating foods high in sugar and fat change brain circuitry.

This is a much more compelling argument for avoiding processed foods and chain restaurants than the message we normally give: avoid them because you'll consume too many calories. Kessler argues that not only will you eat too many calories, eating these foods will cause changes in your brain circuitry that will make you start to crave them--and therefore eat too many calories well into the future. That is a much stronger argument for avoiding fast food and other commercially produced foods than most of us in the obesity field use.

Kessler makes clear that despite the perception that salads are healthier options, many times they are extremely high in fat and calories. Some of the fats may be healthy for your heart, such as those found in avocados and nuts, but many of the other items added to salads are high in both calories in unhealthy fats--cheeses, bacon bits, sour cream, fried tortilla strips/chips/bowls, and cream-based salad dressings. Perhaps hearing that this is well known to the food industry will be enough to change consumers' perceptions of salads.

There is a lot of debate about whether sugar per se is related to obesity. However, as Kessler explains, people now prefer the sugary foods, including salad dressings with sugar. Moreover, highly palatable foods change the wiring in our brains to make us crave these foods. Much of the focus of The End of Overeating is on how these foods change the wiring of the brain, and suggestions for how to combat these changes. Kessler does a nice job explaining a complex body of research findings related to reward-seeking behavior. However, it is disappointing that The End of Overeating fails to cover many other relevant areas of research related to eating behaviors.



study after study that people are driven to eat by factors other than hunger: the eating behavior of their dining companions, the size of the serving spoon, plate or bowl they use, and the amount left in the bowl.

These studies have used both highly palatable foods such as ice cream, as well as foods that are rarely craved, like soup. The results of these studies support Kessler's contention that Americans are driven to eat for reasons other than hunger, but they suggest that causes of overeating are more complex than his book leads us to believe.

Although The End of Overeating briefly mentions Barbara Rolls' research on eating behavior, it deserves more attention. The emphasis in The End of Overeating is on the changes in the types of foods that are now widely available--the hyper-processed and palatable foods. What isn't emphasized enough is the change in portion size. Dr. Rolls and her colleagues have shown that among both adults and children increases in portion size lead to eating more calories. Portion sizes have increased dramatically in the past several decades, and even recipes have changed their serving amounts.

This change may be equally important as the proliferation of highly palatable foods that can causes changed in brain circuitry and result in cravings. Or it may be these changes in combination that we should focus on, since processed highly palatable foods are usually served in large portion sizes.

The last omission worth mentioning is the effectiveness of food industry advertising. A tremendous amount of money is spent on advertising foods, such as breakfast cereals, sugar-sweetened beverages, fast food, and other processed foods high in sugar and fat. Although most people deny that advertisements influence them, studies show that they are indeed heavily influenced. Tom Robinson and colleagues found that young children perceived foods in McDonald's packaging as tasting better than the same food in unbranded packaging.

Taken together, it seems that overeating is caused by a variety of influences in our modern society: the widespread availability of highly processed highly palatable foods high in sugar, fat, and salt; the barrage of advertisements for these nutritionally questionable foods and the restaurants that sell them; the size of the portions we are served; the size of the plates and bowls we use; and the social setting in which we eat. Dr. Kessler is correct in suggesting that many people are being driven to overeat in our modern food environment. But like most tough public health problems, the reasons are even more complex than those offered in his interesting book.