Overeating: A Functional Guide

Though it might sound simple, overeating is a phenomenon that many branches of science have yet to fully grasp. Despite the lack of complete root cause discovery, many theories, treatments, and modalities of healthcare have found addressing the act of overeating to be very successful for promoting weight loss in certain individuals.

So, what is overeating? Overeating is the act of knowingly, or unknowingly, consuming more food volume and calories than is needed to survive. Root causes of overeating can range from hormonal, to structural, to behavioral. Treatment often requires a multi-pronged approach.

Calories In vs. Calories Out

Overeating, or caloric excess, is considered a risk factor for obesity. ¹This means that overeating increases your chances of being obese. Of course, this makes sense. If you eat too many calories you will start to store them as fat. If this is done for a long enough amount of time, eventually fat stores accumulate to the point of diagnosed obesity (BMI ≥ 30). 

Weight gain occurs when calories consumed outweighs calories expended. While there are many things that influence the amount of calories consumed vs. calories expended (the entirety of this blog), overeating is perhaps the most obvious and largest contributing factor to an imbalance between these two variables of weight gain or loss.

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The Mifflin St. Jeor is the most commonly used equation for calculating total energy expenditure in overweight and obese individuals.

Men: RMR = (9.99 X weight) + (6.25 X height) – (4.92 X age) + 5

Women: RMR = (9.99 X weight )+ (6.25 X height) – (4.92 X age) – 161

	Sedentary: Light physical activity associated with typical day-to-day life.	Low Active: Walking about 1.5-3 miles per day at 3-4 miles per hour, in addition to the light physical activity associated with typical day-to-day life.	Active: Walking more than 3 miles per day at 3-4 miles per hour, in addition to light physical activity associated with typical day-to-day life: 60 minutes of at least moderated intensity physical activity.	Very Active: Walking more than 7.5 miles per day at 3-4 miles per hour, in addition to light physical activity associated with typical day-to-day life: 60 minutes of at least moderated to vigorous intensity physical activity.
Males	1	1.11	1.25	1.48
Females	1	1.12	1.27	1.45

***Equations use weight in kilograms (kg), height in centimeters (cm).³

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Though estimating energy expenditure through equations is fairly inaccurate, it is the best estimate we have as clinicians short of indirect calorimetry which requires specialized machinery. 

If caloric intake exceeds estimated total daily energy expenditure, then weight gain will occur. For every cumulative 3,500 excess calories consumed above energy expenditure, one pound of weight gain will occur. This is because one pound of fat is capable of storing 3,500 calories of energy. To be clear, this would occur from cumulative caloric excess. For example, eating 500 extra calories a day for one week would result in a 3,500 calorie excess over the course of the week and a resulting one pound weight gain. 

Epidemiology

Quantifying the prevalence of overeating is difficult to do since we don’t have robust data on total daily energy expenditure for many individuals.⁴ Therefore, most studies focus on caloric intake compared to obesity trends as a measure of overeating. Through these studies, scientists have observed a strong positive association between increases in caloric intake and obesity prevalence. Though these studies cannot prove that overeating is causing the increased rates of obesity, it is generally recognized as the largest risk factor and most likely cause for all the reasons stated above.

Theories of Overeating

Since it is near impossible to determine a single cause for overeating on both a population and individual level, there are countless theories for why individuals may engage in this behavior. I have decided to cover the most popular and likely reasons.

Ultra-Processed Foods

Leading theories on increases in overeating revolve around the increase in ultra-processed foods (UPFs). UPFs are foods that have undergone various forms of food processing such as refinement, extraction, stabilization, preservation, and enhancement. These foods are typically made of ingredients lacking micronutrients, like starches, gums, sugar, oil, and salt. Common UPFs include foods like soda, pizza, candy, burgers, french fries, hot dogs, chips, crackers, deli meats, cookies, pastries, and candy.

UPFs are not the same as minimally processed foods like canned fish, homogenized milk, ground coffee, and frozen fruits/vegetables. 

UPFs are high in calories, sugar, oils, and salt, and low in vitamins and minerals. UPFs are also hyperpalatable, which means that they are chemically engineered to maximize flavor and pleasure. In turn, these foods are often addictive and are very easy to overeat.

As it stands, the average American gets 60% of their daily calories from UPFs. ⁵This means that 60% of calories are coming from low quality nutrient sources that are high in calories. This is a stark increase from UPFs representing less than 5% of total calories in the 1800s. The increase in UPFs has been matched with an increase in total calories. This increase has specifically been in added oils (34%), cereals (31%), and sweeteners (9%).⁶

Hormones

Hormones undoubtedly play a role in the overconsumption of food. Though this is not a root cause for most individuals, it can certainly perpetuate certain behaviors in vulnerable individuals. Below are the hormones most commonly implicated in weight gain and food intake.

Leptin

Leptin is a hormone created by fat cells that promotes feeling of fullness and satiety when there is a caloric excess in the body. Leptin is meant to lower food intake in individuals with excessive amounts of fat. It is the body’s way of saying that you are well fed and do not need anymore food.

As expected, overweight and obese individuals have high levels of circulating leptin.⁷ So, why do obese individuals overeat more and not experience higher rates of fullness? It turns out that the brain can become desensitized to leptin. This is referred to as leptin resistance.

Many obese individuals are also leptin resistant. Though the mechanism is not fully understood, most theories revolve around a combination of inflammation, chronically elevated leptin, and certain genetic mutations.⁸ As a result, individuals with leptin resistance end up unable to intuitively feel fullness and often overeat.

Ghrelin

Ghrelin is a hormone that stimulates hunger. In this way, it is an opposing hormone to leptin. Ghrelin is released from the stomach into the bloodstream before mealtimes to induce the feeling of hunger. Interestingly, obese individuals tend to have lower levels of ghrelin.⁹ This would suggest that hunger would be suppressed in these individuals. However, postprandial (after-meal) levels of ghrelin do not drop in obese individuals as they do in normal weight individuals. As a consequence, obese individuals do not experience a drop in hunger following a meal and therefore engage in longer windows of eating before experiencing fullness. ¹⁰

Fun fact – stress increases the sensitivity of ghrelin receptors in the brain. This means that stress is able to increase hunger on a hormonal level. ¹¹Perhaps this is not so surprising. 

Others

There are many other hormones that play a role in hunger and fullness. These include hormones like cortisol, CCK, thyroid hormone, estrogen, testosterone, and many others. 

Psychology

Overeating is implicated in many psychological conditions. Psychiatric conditions like binge eating disorder, bulimia, depression, and anxiety are associated with overeating. ¹²This blog does not focus on the psychology of weight gain since this is a separate field deserving of its own focused article.

However, overeating with a psychological basis often will not resolve with dietary/lifestyle intervention alone. This subgroup of individuals typically require psychological intervention, such as therapy, to achieve long term results. 

Testing

Testing can be an important part of confirming the diagnosis of overeating. 

Dietary Intake

The most accurate way to confirm a diagnosis of overeating is to do a full 24 hour dietary recall. By adding up all the calories within a day of eating, it can be determined whether or not an individual is consuming more calories than their estimated total daily energy expenditure. 

Food journaling can be an effective way to prevent overeating for certain individuals. However, food journaling can be a risky intervention for those with current or previous diagnosis of an eating disorder.

Triglycerides

Triglycerides represent a type of fat in the bloodstream. In those who regularly overeat, triglyceride levels tend to be chronically elevated. ¹³When triglyceride levels become too high, the risk for heart disease and pancreatitis rises significantly.¹⁴ For this reason, it is important to address elevated triglycerides through diet, lifestyle, and potentially pharmacological intervention.

Leptin

Elevated leptin levels can be a sign of leptin resistance. As previously mentioned, this will make it difficult to regulate feelings of hunger and fullness and typically results in overeating.¹⁵ Improving leptin resistance can be complicated and requires a comprehensive approach.

Melanocyte Stimulating Hormone

Melanocyte stimulating hormone (MSH) is important for the suppressing appetite in the brain. Having low levels of MSH can lead to overeating. ¹⁶

Treatment

Treatment of overeating is complex and is deserving of complete personalization. However, I have included some common interventions with good data to support their use.

Protein

Following a high protein diet can be an effective way to achieve weight loss by preventing overeating. High protein diets have been shown to reduce appetite by stimulating the secretion of various fullness hormones.¹⁷ These hormones include glucagon-like peptide-1, cholecystokinin, and peptide tyrosine-tyrosine which are collectively categorized as anorexigenic hormones. Anorexigenic hormones reduce appetite and food intake as the name implies.  

Those who follow a high protein diet are full quicker, eat less food, and burn more calories digesting their food.¹⁸ For this reason, a high protein diet may be appropriate for combatting weight gain from overeating.

Protein supplements can be a great way to increase protein intake while avoiding higher calorie foods like certain meats. Protein supplements would include products like protein powders, branched chain amino acids, and certain protein bars/beverages. Though all have their time and place, finding a high quality protein powder is the best place to start.

When choosing a protein powder it is important to consider the sourcing. Protein powders are either plant-based or animal-based. For animal-based protein powders, I recommend choosing a whey protein isolate. For plant-based protein powders, I recommend finding one that has at least 2 grams of leucine. You can usually find this information on the nutrition label under the “amino acid profile” section. Leucine is needed to stimulate muscle protein synthesis, the conversion of dietary protein into skeletal muscle. There is no clear amount needed, but plant-based protein powders tend to be lower unless otherwise stated.¹⁹

Fiber

Fiber refers to the indigestible carbohydrates within a food. Fiber serves to slow the transit of food through the digestive tract, stabilize blood sugar, and provide a fuel source for the microbiome. Increased fiber intake is directly correlated to lower body weight.²⁰ Increasing fiber intake can be an effective way to improve feelings of fullness when following a low calorie diet for weight loss.²¹

Various studies have attempted to discern which supplemental fibers are most effective at reducing hunger to prevent overeating. As it stands, there is no clear choice for which fiber to choose. Different fibers have different benefits to satiety, immune function, microbial balance, and blood sugar control.²² However, only 39% of studies find that supplementing fiber is effective at lowering appetite.²³ For this reason, a diverse array of fibrous foods likely has more benefit than any specific fiber supplement.

For those who must know – A 2019 meta-analysis showed that guar gum, β-glucan, alginate, polydextrose and pectin are all effective at reducing appetite, with guar gum being the most effective.²⁴ I recommend taking this with a grain of salt since focusing on just one fiber source can potentially lead to dysbiosis.

Whole Foods

Adhering to a whole foods diet can be an effective way to prevent overeating and lose weight. This is largely through two mechanisms. First and foremost, a whole foods diet eliminates UPFs. Since UPFs are one of the main causes for overeating, and obesity at large, removing them from the diet is a great place for anyone to start who is looking to lose weight. Secondly, whole foods are high in nutrients like protein and fiber. As previously mentioned, these nutrients both are important for regulating appetite and preventing overeating. Therefore, opting for a diet that is high in whole food vegetables, fruit, grains, and unprocessed animal products can be a great way to prevent overeating.

Psychological Treatment

For those who have trouble overeating, I often recommend investigating a psychological root cause. This is especially important if dieting has failed multiple times. For these cases, therapy combined with nutrition can be much more effective than dieting alone. If you suspect a psychological root cause but are unwilling to investigate therapy as a route of healing, I implore you to reconsider if this is getting between you and your health goals. 

Conclusion

Overeating is a common cause of weight gain and can be more difficult to identify than most people recognize. There are many causes for overeating, with the increase of UPFs in the diet being the leading cause. However, other factors like certain hormones and psychological conditions cannot be ignored. For this reason, it is recommended to work with a professional to obtain a comprehensive plan to lose weight safely and effectively.

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