The CICO (calories in, calories out) approach to weight management is popular because it seems simple. If you consume fewer calories than you burn through exercise and daily living, you’ll lose weight (1). Take in more calories than you need to fuel your lifestyle, and you’ll gain weight (1). If you meet your body’s calorie needs on the nose, you’ll stay the same (1).
This simple approach is effective for many, but there are several CICO myths that can oversimplify things. These myths might mislead you into thinking that weight management boils down to a math equation.
In this article, we’ll debunk some of the most common misconceptions surrounding CICO and provide a clear understanding of how it works so that you can get the most from this tool.
The Myth: CICO is Simple
One of the most common CICO myths is that it’s a simple energy balance equation. The premise is that all it takes is a calorie surplus or deficit to gain or lose weight.
The truth: weight loss is complicated
“While the CICO method is simple in concept—eat fewer calories than you burn in order to lose weight—it isn’t the whole picture of how safe and sustainable weight loss happens,” says Melissa Jaeger, RD, LD, Head of Nutrition at MyFitnessPal (1).
Your body is complex. Many factors, like genetics, age, and hormones, impact body weight (1). Also, every individual body processes nutrients from foods a little differently (2).
In other words, your body isn’t a calculator. Weight loss is more than just calories in, calories out.
The takeaway
Although CICO literally stands for calories in vs. calories out, CICO is just an informal way of expressing the energy balance equation (1).
However, weight management isn’t as simple as that. The quality of your food, your metabolic rate, and individual differences all influence how your body manages weight (1, 2). So, does this mean you shouldn’t do a CICO diet? Not exactly, but it’s important to remember that it’s one factor among many when it comes to your weight.
The Myth: You Can Eat Whatever You Want as Long as You Stay Within Your Calorie Limit
A common myth surrounding the CICO approach is that all calories count the same way, whether they come from protein, carbs, fats, or processed foods.
This gives you the impression that as long as you stick to your CICO calorie goal, it doesn’t matter what types of food you eat or when you eat them, such as late at night.
The truth: there’s a lot more to it
It’s helpful to be aware of the number of calories your body needs to lose, gain, or maintain your weight, however, there’s much more to it than that (1).
According to Jaeger, “One downside of focusing solely on calories in vs. calories out is that it doesn’t teach us the importance of the nutrients in those calories (2).” When you focus only on the big picture numbers and not the components that make up those numbers it can be challenging to adopt healthier habits and honor our bodies’ hunger and satiety cues during our weight loss journey (2).
When you eat influences weight management, too. Our bodies are designed to eat when it’s light and fast when it’s dark. Disruptions to this rhythm can short circuit your body’s feedback signals and response to food, resulting in a higher chance of weight gain (3).
The takeaway
The quality of your food and meal timing affects your hunger and overall health (2, 3). Focus on eating quality foods, such as protein- and fiber-rich, nutrient-dense foods, and getting most of your food within daylight hours (2, 3).
The Myth: Cutting 3,500 Calories Always Equals One Pound of Weight Loss
A longstanding belief is that 3,500 calories is the number of calories in a pound, so it’s been thought that reducing your calorie intake by this much will result in a pound of weight loss.
The truth: weight loss can be unpredictable
The reality is that our bodies don’t lose weight in such a predictable way. Factors like metabolism, muscle mass, stress, and genetics impact how your body responds to calorie deficits (1). As you lose weight, your body will burn fewer calories, slowing down your progress (4). Basically, your personal outcome is less straightforward than the math suggests.
The takeaway
Instead of relying on the 3,500-calorie rule, focus on creating sustainable habits—like eating filling foods—that support long-term health in addition to weight management (2).
Non-starchy veggies and protein are a filling duo, so I encourage my clients to make a habit of including at least 20 grams of protein and a half plate of non-starchy veggies at each meal. Bonus: Recent research suggests that losing weight in a gradual fashion is better for your metabolism (5).
About the Experts
Melissa Jaeger, RD, LD is the Head of Nutrition for MyFitnessPal. Melissa received a Bachelor of Arts in Nutrition (DPD) from the College of Saint Benedict and completed her dietetic internship through Iowa State University. In May 2024 she was recognized as the Registered Young Dietitian of the Year awarded by the Minnesota Academy of Nutrition and Dietetics.
Samantha Cassetty, MS, RD, is a nationally recognized food and nutrition expert, media personality, nutrition consultant, and author. Cassetty is a former nutrition director for Good Housekeeping and the co-author of the book Sugar Shock.
The Myth: CICO is Just About Food and Exercise
Another common misconception is that the CICO approach is only about how much you eat and how much you exercise, which may lead you to overlook other important factors that influence weight management.
The truth: Many other lifestyle factors count
While food and exercise are critical components of weight management, so, too, are other eating and lifestyle behaviors. For instance, poor sleep can disrupt hormones that regulate hunger and satiety, leading to overeating (6). Additionally, high stress can increase levels of cortisol, which may promote fat storage, especially in the abdominal area (7).
Your metabolic rate is influenced by factors like age, muscle mass, and even certain medical conditions. All of this means that simply cutting calories or increasing exercise may not always lead to the predicted results (1).
The takeaway
CICO is not just about diet and exercise. To achieve sustainable weight loss and overall wellness, it’s essential to consider sleep, stress management, and diet quality (1, 2). That doesn’t mean attempting to overhaul all of your habits at once. Making some tweaks to your diet to achieve a calorie deficit is a great first step!
The Myth: All Calories Are Created Equal
A common belief is that a calorie is a calorie, regardless of its source—whether those calories come from strawberries or strawberry ice cream.
The truth: The quality of your calories plays a role in weight management (2)
Case in point: A small, well-designed 2019 study compared calorie consumption and weight gain on an ultra-processed food diet to a minimally processed diet. People followed one diet and then switched to the opposite diet after a washout period–the time between the two diets when there’s no prescribed eating plan (2).
Even though the meals provided to both groups had the same amounts of calories, fat, sugar, fiber, carbs, and protein, participants on the ultra-processed diet consumed about 500 more calories per day than those on the minimally processed diet.
The processed food group gained an average of two pounds during the two-week period. However, these same folks lost the same amount of weight (about two pounds) on the less processed diet over two weeks following that eating pattern.
The takeaway
Food quality is an important part of the weight loss equation. Jaeger suggests using MyFitnessPal to help you choose nutritious foods for weight management. “Tracking with MyFitnessPal can help you not only identify your total daily calories for weight loss, but also key nutrients, such as protein, fiber, and saturated fat, to support your health and fitness goals.”
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The Myth: CICO Is the Same as “Eat Less, Move More”
CICO stands for calories in, calories out, so it’s easy to understand why many people think it boils down to eating less and moving more.
The truth: There’s more nuance
While calories and movement are part of your energy balance equation, there’s more to it than that. (1) Other factors, such as your weight history, genetics, muscle mass, sleep patterns, stress, and age can affect your weight (1).
The takeaway
Think of calories in, calories out (AKA eat less, move more) as an informal way of expressing the energy balance equation instead of the end-all be-all for weight management (1).
The Myth: Counting Calories is Necessary for CICO
Given that CICO stands for calories in, calories out, many people think that counting calories is a mandatory part of following the CICO approach to weight management.
The truth: Though helpful, it’s not strictly necessary
Studies show that being mindful of your food quality and eating habits (such as portion control and eating mindfully) can still lead to weight management without tracking every single calorie (8, 9).
However, calorie counting can provide structure and awareness, and a 2021 study found that people are more successful with weight loss using tracking tools, including diet-tracking tools like MyFitnessPal (10).
The takeaway
While calorie counting can be helpful, it’s not the only path to success with CICO (8, 9). Mindful eating, portion control, and focusing on the quality of your diet are additional strategies to help you achieve your goals without strict tracking (8, 9). Though, MyFitnessPals’s new Premium voice logging feature makes tracking food—and calories—faster than before in the app.
CICO Works the Same for Everyone
The myth
A common CICO myth is that everyone will lose or gain weight at the same rate if they follow the same caloric deficit or surplus. In other words, people mistakenly believe that it’s all about the numbers.
The truth: Everyone is different
In reality, CICO doesn’t account for individual differences in metabolism, genetics, muscle mass, sleep patterns, and stress, all of which can significantly influence your weight (1).
For instance, if you have a slow metabolism and are over 50, you’ll likely have different results from someone with a fast metabolism who’s 25, even if you’re adhering to the same caloric deficit or surplus (1).
Key takeaway
CICO can be a helpful framework, but it’s one of many factors that influence your body weight. So it’s helpful to tailor your weight loss approach to your needs and circumstances (1).
Frequently Asked Questions (FAQs)
Can you out-exercise your diet?
A sweaty exercise sesh feels tough, so you might think it can counter the damage from an unhealthy diet. But this simply isn’t true. Research shows that exercise alone doesn’t promote significant weight loss (10, 11).
Plus, a diet full of saturated fat, sodium, and excessive sugar can undermine your health (12). Exercise is a health-promoting activity, and there are plenty of reasons to participate in it regularly–including help with weight maintenance–but it can’t outdo an unhealthy eating pattern (11).
Can CICO be used for anything other than weight loss?
CICO is a way to express the energy balance equation, so it can be used for weight loss, weight gain, or weight maintenance (13).
Do you always need to be in a calorie deficit for CICO to work?
There are many factors involved in weight loss. Aside from a calorie deficit, the quality of foods you eat, access to foods, hormones, genetics, stress, and sleep patterns all play a role (1).
Additionally, you’ll need an energy surplus for CICO to work for weight gain (13). If you’re trying to maintain your weight, you’ll need roughly the same number of calories in vs. calories out (13).
Does meal timing matter with CICO?
While calorie balance is a factor in weight management, meal timing can influence hunger, energy levels, and metabolism (3). Eating irregularly or skipping meals can lead to overeating later in the day, which makes it harder to maintain a calorie deficit or balance.
Additionally, eating at consistent times—especially earlier in the day—can help regulate blood sugar levels and support a healthy metabolism, as your body processes food more efficiently when you’re active (14).
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