Why We Overeat and How To Prevent It

You’ve just finished a delicious meal at a restaurant and you are stuffed (Thanksgiving full!)—you couldn’t possibly eat another bite. And then the waiter brings by the dessert tray and you decide you have to have the cheesecake. You sit down to watch TV and grab a bag of chips and start munching on them since you typically eat a snack when you watch TV and before you know it, the bag is empty. You ate way more than you planned on and more than you were hungry for. In both of these scenarios, you were overeating. We have all been in situations like these. The definition of overeating in the Cambridge Dictionary is “the action of eating more food than your body needs, especially so that you feel uncomfortably full”. Overeating on a regular basis will lead to weight gain, which typically involves increasing the amount of body fat a person has.

According to the Centers for Disease Control and Prevention (CDC), in 2017-2018, about 73% of adults and had overweight or obesity which has increased from about 65% in 1999-2000. This is a huge problem since obesity-related conditions such as heart disease, stroke, type 2 diabetes and certain types of cancer are some of the leading causes of preventable, early deaths in adults. 

Ultra-processed foods compared to unprocessed foods

So why are so many adults gaining weight? A researcher at the National Institutes of Health named Kevin Hall is trying to answer this question by looking at the characteristics of the current food environment that regulate appetite and cause people to overeat. Volunteers for Dr. Hall’s research spent several weeks living in a lab in 2019 so that Dr. Hall could accurately measure what people ate and how many calories they burned. Participants were offered mostly unprocessed foods (vegetables, fruits, beans, nuts, seeds, poultry, seafood, meats, eggs, milk, unflavored yogurt, oats, rice, unsweetened shredded wheat) for 2 weeks and then ultra-processed foods (sugary drinks, chips, ice cream, chocolate, packaged sweets, flavored yogurts, breakfast cereals, frozen pizza, fish sticks, chicken nuggets, hot dogs, instant soups) for 2 weeks. During both time periods participants were told to eat as much or as little of the food as they wanted. On average, people ate 500 more calories a day when eating the ultra-processed foods compared to the unprocessed foods, which led them to gain weight and body fat. The ultra-processed foods had a higher caloric density than the unprocessed foods, which means that the ultra-processed foods have more calories per bite of food. For example, 1/2 square of dark chocolate has about 33 calories while one baby carrot has 4 calories. This would help explain why the people who were eating the ultra-processed foods ate more calories.

So what is it about ultra-processed foods that could lead people to overeat?

Our bodies are designed to store body fat and defend against efforts to decrease the amount of body fat we have. In hunter-gatherer societies (about 12,000 years ago), having extra body fat could mean the difference between living and dying. In today’s society where food is more available and plentiful we don’t need to have excess body fat to ensure we survive during times of famine.

About 50 years ago, food companies started doing research to figure out how to entice people to eat more of the food they produced. Food companies sought to take advantage of our natural urge to keep eating by manipulating the amounts of sugar, fat and salt in their products. They also focused on other factors to boost sales such as increased variety of flavors, ease of eating the foods, encouraging snacking, keeping foods low cost, and advertising. The end result is to try and get people hooked on eating their food products.

Sugar: The food industry came up with the term “bliss point” to describe the perfect amount of sugar (not too little and not too much) in a drink or food. 

Fat: Many snack foods like potato chips have 50% of the calories coming from fat. This creates a melt-in-your-mouth sensation so you often don’t need to chew the foods much.

Salt: Having a lot of salt in foods, especially on the surface of the food, is very appealing since salt provides a burst in flavor as it touches the tongue.

Fat plus carbs: Foods that contain both high amounts of fat and refined carbohydrates like ice cream, french fries, pizza and cookies are the foods people find the most irresistible.

Variety: Eating a variety of food increases the chances of getting all the nutrients we need. However, having access to a variety of foods can also compel people to eat more. When people were served sandwiches with 4 different fillings, they ate a third more than when they were served sandwiches with only one filling.

Ease of eating: Ultra-processed foods usually take less time to eat than unprocessed foods which can result in eating more of the ultra-processed foods. Unprocessed foods often need to be chewed more due to having more intact fiber and being crunchier. 

Encouraging snacking: The food industry has created many products to encourage us to snack during the day. These food products are convenient to eat while doing something else (such as watching TV or working on a computer) which can cause our brains to ignore signals from our stomachs that we are getting full.

Low cost: Food companies try to make products as cheaply as possible in order to increase their profits and to sell more of their product to budget conscious consumers. They will often use flavors that mimic the taste and smell of real foods which helps keep their costs low.

Advertising: TV ads for food products will often focus on creating strong food memories by showing their product as they are triggering our emotions with the content of the commercial. The idea is to influence our food preferences to increase consumption of ultra-processed foods.

What can we do to prevent ourselves from overeating?

• Decrease the amount of ultra-processed food you eat and focus on eating foods with a lower calorie density. To determine calorie density of a food: divide the calories of a food by its weight in grams. The baby carrot we talked about earlier weighs about 10 g and has 4 calories so 4/10 = 0.4. Most fruits and vegetables have a calories density of 1 or less. By aiming to have half of your plate contain fruits and vegetables you can lower the overall calorie density of your meal.
• Use a smaller plate when eating a meal. We tend to feel more satisfied when we have a smaller plate full of food compared to when we have a larger plate that is only half full.
• Don’t let yourself become too hungry before you eat something. It is difficult to make good choices about what you will eat when you are ravenous. You will also likely serve yourself more food than you need and eat faster.
• Don’t completely cut out all the higher calorie density foods you love because this will likely cause you to feel deprived. Rather, occasionally eat small portions of some of the calorie-dense foods or ultra-processed foods you really enjoy. (Remember you have one FREE MEAL each month. This is a great opportunity to eat some of the foods you really enjoy that are not part of the Basic Principles.)
• Practice Mindful Eating: being aware of both the physical and emotional feelings connected to eating and learning how to reconnect with hunger and fullness signals.
  • Eat more slowly. Take at least 20 minutes to eat a meal so that your stomach has time to communicate with your brain that you have had enough to eat. Try eating with your nondominant hand, use chopsticks, and/or take sips of water between bites of food.
  • Savor your food. Notice all of the colors, smells, flavors, and textures of the foods you are eating.
  • Avoid doing other activities while you eat (such as working, talking on the phone, watching TV, driving, reading, etc.). Relax and enjoy your meal.
  • Before you reach for food, ask yourself if you are really hungry or if you are wanting to eat because you are bored, sad, stressed, or tired. Or perhaps you want to eat out of habit, but aren’t actually hungry. Some symptoms of hunger are a growling stomach, headache, feeling lightheaded, lack of energy, shakiness or weakness, and feeling grumpy.

Information compiled from:
https://www.cdc.gov/nchs/data/hestat/obesity-adult-17-18/overweight-obesity-adults-H.pdf
https://www.cdc.gov/obesity/data/adult.html
“Why We Overeat” by Bonnie Liebman Nutrition Action Healthletter April 2021
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