It can be quite the dilemma: If I overeat one day, should I undereat the next? While this question about over- and undereating may seem to have a simple yes-or-no answer, the reality is complex. It’s important to look at the body’s biological and psychological response to restriction to determine the best course of action the day after a binge.
To give you a little taste of what’s in store, the short answer is no, overeating should not be compensated by an “equal” amount of undereating because the body will employ biological responses to restriction that actually increase the likelihood of weight gain and overeating. Since the goal is often to prevent weight gain (why else would we diet) it’s important to understand what’s really going on.
Metabolism and caloric balance are important factors to consider when you’re tempted to undereat in response to a binge. Of course, I will also loop in some eating psychology as well because that part is my favorite!
The Dilemma: If I Overeat One Day, Should I Undereat the Next?
On the surface, it seems reasonable to compensate for overeating by undereating on the following day. However, this mindset oversimplifies your body’s complex biological processes and can actually harm your metabolism, potentially resulting in weight gain, not weight loss.
The concept of caloric balance is at the heart of the question, “If I overeat one day should I undereat the next?” It’s the idea that maintaining weight is as simple as balancing the calories you consume with the calories you burn. However, our bodies are far more complex than simple mathematical equations.
The concept of "calories in equals calories out" neglects many other factors, such as the thermic effect of food (the energy your body uses to digest food), the quality of the food you eat, and even the impact of stress and sleep on your metabolism.
Your body can adapt to prolonged periods of overeating or undereating by adjusting your metabolic rate (more on this soon). Therefore, undereating the day after overeating doesn’t necessarily mean you’ll “balance out” the extra calories consumed.
Overeating and Undereating: The Impact on Metabolic Cycles
Let’s dive deep into that word: metabolism. Most of us relate to metabolism as something we want to speed up, but there’s much more to it than that. Metabolism is responsible for converting food into energy. It has two primary modes: fed (anabolic) and fasted (catabolic).
During the fed metabolic state, your body digests the food you consume, and excess calories are stored for future use. During the fasted state, your body uses these stored energy sources. (Many of us are familiar with these concepts from the popular intermittent fasting diet.)
Like every diet, the problem happens when we don’t “stick with it” and therefore we don’t benefit from the benefits of dieting. While it may seem like a lack of willpower to lose weight, dieting itself is largely to blame because of the biological cascade of events (that I am about to explain) that happen when we restrict calories.
In an ideal world, intermittent fasting would lead to long-term weight loss because we would eat within our “eating window” without fail. But the truth is that: for every restriction, there is an equal and opposite binge. When we fall off the wagon and overeat or binge while we are on a diet, we may be tempted to restrict our diet the following day (thus the question that inspired this article: “If I overeat one day should I undereat the next?”)
But when we drastically alter our calorie intake from day to day, it disrupts the body’s metabolic cycles. Overeating one day and undereating the next can cause metabolic confusion, which may cause more overeating and even weight gain.
“Metabolic Confusion” Explained: When You Overeat One Day and Undereat the Next
Metabolic confusion happens when your body responds to unpredictable calorie intake. When you overeat one day and undereat the next, your body may struggle to regulate its energy balance efficiently. This can lead to unstable energy and potentially affect your metabolic rate.
In other words, overeating one day and undereating the next can slow down your metabolism and potentially lead to weight gain and feelings of lethargy. Ironic, isn’t it? We restrict our diet to hopefully avoid weight gain, but biological responses to calorie restriction actually hinder our ability to lose weight.
When you undereat, your body might perceive this as a sign of food scarcity and, in response, might lower your metabolic rate to conserve energy. This adaptive response, known as metabolic adaptation or “starvation mode,” can mean that your body becomes more efficient at using energy, leading to fewer calories burned overall.
Consequently, if you then overeat, your body, operating at this lowered metabolic rate, will store more of the excess calories as fat, contributing to weight gain.
Beyond Metabolism: The Impact on Hormones & Psychology
The mindset of “I overate yesterday, so I should undereat today” can foster a diet mentality, characterized by restriction and fixation on food, and even feelings of guilt after eating. This mentality can negatively affect your relationship with food and lead to a vicious cycle of yo-yo dieting.
Moreover, undereating can also have significant impacts on your hunger and satiety hormones. Levels of ghrelin, also known as the “hunger hormone,” can increase when you’re not eating enough, while levels of leptin, the “satiety hormone,” can decrease.
This hormonal shift can make you feel hungrier and less satisfied after eating, leading to increased appetite and potential overeating when you do allow yourself more food. Over time, this pattern can contribute to weight gain.
Standing in front of the fridge, this level of happiness is completely unrelatable for those of us struggling with the restrict-binge cycle
Also, the feeling of deprivation that comes from undereating can affect us psychologically. It’s common to overeat or crave high-calorie, less nutritious foods after a period of restriction, which is often referred to as the “rebound effect.” This overcompensation can also lead to increased caloric intake and, again, potential weight gain.
Understanding your biology can help you save time, energy, and your mental health – since you’ll ease feelings of self-defeat that stem from the restrict-binge cycle. Many of us restrict our diet in order to lose weight, but the body’s response to restriction actually encourages the opposite effect.
By letting go of dieting, we free ourselves from the restrict-binge cycle, put an end to metabolic confusion, and reap the benefits of improved physical and mental health.
Giving Up Dieting as a Potential Answer to: If I Overeat One Day Should I Undereat the Next?
“Dieting” often implies a temporary change in eating habits, usually involving restriction, deprivation, and a preoccupation with the number on the scale. This perpetuates the overeating-undereating cycle we’re trying to avoid. Instead, we can replace dieting with a focus on nourishing our bodies rather than just losing weight.
Many of us are worried that, if we don’t follow a diet, we will end up craving nothing but carbs and sugar and binge on these “bad” foods. This is far from the truth! What happens when you stop dieting is complex. It may initially begin with episodes of indulging in previously forbidden foods. But after that stage, a healthier relationship with food emerges.
Redeveloping trust in yourself around food can be difficult and scary, but it’s far more helpful than remaining in the restrict-binge cycle for years and years.
If you’re genuinely hungry, eat. If you’re satisfied, stop eating. And if you can’t get yourself to stop eating when you aren’t hungry, use emotional eating tools such as the Stop, Drop, & Feel.
Occasional indulgences are a normal and enjoyable part of life—they're not something to feel guilty about or to compensate for with restrictive behaviors. Having days where you eat more than usual is perfectly okay and does not need to be "undone" by undereating the next day.
Instead, just return to listening to your body to inform what you eat without guilt or stress. Ultimately, it’s the overall pattern of your eating habits, not one single day of overeating, that contributes to your health and wellbeing.
Balance and Consistency Over Compensation
I hope this article helps you give yourself more credit. Your body is not a simple calculator doing “calories in, calories out” math. It’s complex and automatically adjusts to changes in your diet in multiple ways. This is evident in how your metabolism and hormones work, and even in your psychology.
Ditching the diet mindset is the ultimate answer to, “If I overeat one day should I undereat the next?” Shift from food restriction to prioritizing nourishment. Break free from the restrict-binge cycle by redeveloping trust in your body’s ability to regulate itself so long as you keep trying to listen to it.
