A common piece of advice for anyone looking to shed pounds is the age-old “calories in, calories out” principle: if you increase your energy expenditure relative to your caloric intake, the excess weight will melt away. You can understand the allure of reducing weight loss to a mathematical formula:
- If you follow the formula, you will succeed. Many people do see initial weight loss when they start using this method, so it’s plausible.
The society holds individuals responsible for their weight because the diet industry promotes the “calories in, calories out” notion. Only a lack of self-control in cutting back on food and increasing physical activity can explain why some people can’t seem to stick to this basic energy formula. To be sure, there are many simplistic theories on weight loss, but the one that needs to be dispelled is the “calories in, calories out” fallacy. Now I’ll tell you why.
Precise Calculation is Next to Impossible
Apps and online calculators abound that make keeping track of calories appear simple. For a daily calorie deficit diet plan tailored to your specific needs, all you have to do is plug in your gender, age, height, weight, body fat percentage, and amount of physical activity.
No matter how precise these calculators say they are, they still use averages and can’t tell you exactly how many calories you should be eating. Estimates are all they can do.
The amount of energy we expend while at rest, or our metabolic rate, differs from one individual to the next for a variety of reasons, one of which is our body composition, which includes the proportions of muscle and fat. To make matters more complicated, when we lose weight and make dietary changes, our metabolic rate also changes.
Another aspect of managing “calories in” that is wildly inaccurate is calculating the calories in food. Although Nutrition Information Panels showing kilojoules of energy must be displayed on commodities in Australia, there are no guidelines for the quality of this information other than that it must not be misleading. The quantities shown on labels typically have a concerning +/-20% mismatch. This kind of diversity is not uncommon in reality. The amount of calories or nutrients in food varied from 13% to 61% higher or lower than what was advertised on the box, according to one Australian study.
Calories Are Neither Produced or Eaten in the Same Way
The fact that our bodies don’t use all calories in the same way is another nuance that makes the “calories in, calories out” formula complicated. The number of calories that your body absorbs is different from what your calorie counter shows.
Hormones, brain response, and energy expenditure are all impacted differently by various calorie sources, which in turn affects how we react to and control the amount of food we eat. In terms of total caloric intake, 90 calories from nuts is equivalent to 180 calories from pizza, but the absorption rate and physiological effects of these two foods couldn’t be more different.
Nuts have fat that is held in fibrous cell walls that do not break down during digestion, so whereas we absorb the majority of the calories in a piece of pizza, we do not absorb around 20% of the calories in nuts. The high fiber level of nuts keeps us full for longer than the low fiber content of pizza, which makes us want another slice as soon as we eat it.
When Our Bodies Break Down the Formula
The “calories in, calories out” formula fails miserably because it does not take into account the fact that the body’s control systems change in response to a decrease in caloric intake. While the formula may help people lose weight at first, it has systems in place to make sure they gain it all back even when they cut back on calories.
To be more specific, your body perceives a danger to its life when it detects a continuous decline in the number of calories you take in. To counteract this danger, our bodies go into autopilot mode and begin to cut back on energy expenditure, including lowering our metabolic rate. Our evolutionary lineage includes hunter-gatherers, whose bodies adapted this reaction to stave off starvation during times of food scarcity. Studies have shown that our bodies strive to stay at a certain weight, called our “set point weight,” no matter how much or how little exercise or healthy food we consume.
As we cut calories in anticipation of future calorie decreases, our bodies manage biochemical signals from the brain and hormones to preserve fat stores, protecting our set point.
There are multiple pathways the body takes to accomplish this, and they all have an impact on the “calories in, calories out” calculation:
- Lower metabolic rate: Cutting calories to lose weight causes the loss of both fat and muscle. The metabolic rate drops as one would expect it to due to a loss of muscle mass, but the extra 15% drop in metabolism throws the “calories in, calories out” calculation for a loop. Our metabolism doesn’t get back to normal even when we gain back the weight we lost. Reducing caloric expenditure while at rest changes the equation since our thyroid gland malfunctions and secretes fewer hormones when we cut back on meals.
- Changing the way we utilize energy: We burn less energy at rest when we cut back on calories and begin to lose weight because our bodies shift their energy source from fat to carbs and keep their fat stores.
- Supervising the adrenal gland’s activity: In response to physical stress, such as calorie restriction, our adrenal glands secrete the hormone cortisol. Our bodies alter their fat processing, storage, and burning mechanisms when cortisol levels in the blood are high.
In a cunning move, our bodies also set in motion reactions that encourage us to eat more calories to put the weight back on, such as:
- Modifying the hormones that induce hunger: When we cut back on calories and starve our body, our hormones react differently, making us feel full on less and wanting to eat more.
- Influencing the way our brains work: We lose some control and judgment over the food choices we make when we cut back on calories because our hypothalamus, the brain region responsible for controlling appetite and emotional eating, is less active when we do so.
Because it simplifies the complicated process of measuring energy expenditure and intake, the “calories in, calories out” formula for weight loss success is a fiction. Even more crucially, it disregards how our bodies react to calorie restriction. So, while the mixture may help you lose weight temporarily, it’s likely that you’ll put it all back on.
Calorie monitoring can lead to an unhealthy connection with food and remove the joy from eating, which is the opposite of what it aims to achieve. It might become much more challenging to reach and stay at a healthy weight when that happens.
Following healthcare providers’ evidence-based programs and making small, sustainable adjustments to your lifestyle are the best ways to lose weight and keep it off for good.