Eating Less and Moving More: Why It’s Not That Simple

Egg, asparagus, and tomato on a plate.

In a world increasingly marked by convenience foods and sedentary lifestyles, obesity has staked its claim as one of the defining health crises of our era. Many might think the solution is as simple as ‘eat less, move more.’ This is rooted in the concept of maintaining a calorie deficit: burn more calories than you consume.

However, modern science suggests calorie deficit, while theoretically sound, may not be the magic bullet we once believed. Not only can drastically reduced caloric intake lower one’s metabolism, making it harder to shed weight in the long run, but it can also lead to nutritional deficiencies and heightened feelings of deprivation. The human body is a complex machine, and the path to optimal health might be more intricate than a basic math equation.

Our health is like a jigsaw puzzle, and while calories are an important piece, it’s the combined understanding of nutrition, gut health, and eating psychology that paints the complete picture.

How calorie deficit works

Calorie deficit boils down to a simple mathematical principle: you must burn more calories than you consume. It can be achieved in two primary ways–either by consuming fewer calories than your body burns or by increasing your physical activity to burn more calories, or ideally, a combination of both.

How to calculate calorie deficit

To calculate a calorie deficit, the first step involves determining daily calorie requirement. This requirement is based on several individual factors, including height, weight, sex, age, and activity level. There are numerous formulas available to estimate this daily energy expenditure, with the Harris-Benedict Equation and the Mifflin-St Jeor Equation being among the most commonly used.

Once daily maintenance calorie intake has established, people can then decide on the size of the deficit they wish to create, which is often influenced by the desired speed of weight loss. Subtracting calorie deficit goal from the daily maintenance number gives people the number of calories they should consume daily to achieve that deficit.

For those who prefer a more streamlined approach, many online calculators simplify this process by completing both steps simultaneously, offering a user-friendly interface where users input their details and immediately receive the calorie recommendations based on the chosen deficit.

The Struggles and Triumphs of Calorie Deficit

Here lies the crux of the problem: human beings are remarkably poor at accurately accounting for the food they consume. Add to this the intricate metabolic intricacies that evolution has bestowed upon us, and the energy we expend becomes a conundrum that’s nearly impossible to decipher. When asked to recall their daily diet, the results are often skewed by significant margins. Recent studies indicate that adults underreport their actual food intake by a staggering 29%—that’s the equivalent of omitting an entire meal from one’s daily recount!1

That isn’t where the story ends. There are manifold reasons why the simple act of counting calories can mislead many on their weight loss journey. A dedicated individual embarked on a journey to shed some pounds, meticulously trimming her caloric intake. Her efforts bore fruit as the scales tipped in her favor, showing a significant weight loss. However, as time went on, she encountered a challenge; even while maintaining her tried-and-true diet, her weight loss came to a standstill before she could reach her desired goal.

Kevin Hall, a renowned researcher from the National Institutes of Health, offers insight into the phenomenon. Firstly, as one drops weight, the now-smaller body requires less energy. Thus, the calorie deficit that was once driving weight loss starts to narrow, leading to a plateau. Secondly, weight loss can inadvertently boost one’s appetite, posing additional challenges in preserving that vital calorie deficit. For those facing such a stall, reigniting the weight loss process requires establishing a new calorie deficit.

Reframing the Calorie Deficit Discourse

1. Our Body’s Remarkable Response to Calories

Calorie intake and expenditure are interdependent variables, continuously adjusting to maintain the body’s energy balance. It’s tempting to believe that merely counting calories is the key to weight management. Yet, our bodies are finely tuned systems that adjust to caloric changes with impressive efficiency.

When we reduce our caloric intake, a mechanism called adaptive thermogenesis or metabolic adaptation kicks in2, leading to decreased resting metabolic rate and, thus, minimal weight loss. This process can be likened to a thermostat adjusting to maintain room temperature. Similarly, as we gain weight by consuming more calories, our bodies require more energy to support this added tissue. It is a natural survival instinct in humans to store energy against the possibility of starvation and a low food supply, even though this is not related to current circumstances.

Still, it’s important to emphasize that this adaptive thermogenesis continues for successful weight losers, which is not a bad news, right?

2. The Secret Drivers of Our Daily Energy Expenditure

It’s a widespread belief that our body’s energy expenditure is fairly constant and only spikes when we exercise. Imagine a car that only guzzles gas when it speeds up, but otherwise sips it steadily. Our bodies, however, are not that straightforward.

The total energy expenditure is a beautifully complex interplay of multiple factors, not just physical activity. This includes the Basal Metabolic Rate (BMR)—the energy required to keep our bodily functions running even when we’re at rest, the Thermic Effect of Food (TEF)—energy used to digest, absorb, and metabolize food, and the often underestimated Non-Exercise Activity Thermogenesis (NEAT)—energy expended during non-exercise movements like fidgeting or even standing3.

So, while the sweat and burn from a workout session are definitely crucial, it’s essential to remember that the body’s intricate symphony of energy use goes way beyond the treadmill. Let’s not oversimplify this marvel of human physiology; after all, every twitch, thought, and taco has its part in the energy equation.

3. Hormonal Shifts in the Weight Loss Journey

Have you ever wondered what exactly triggers that growling in your stomach or that sudden urge for a midnight snack? Our bodies operate on a sophisticated system of overlapping hormonal signals that help us determine when to eat and when to put the fork down. Before you even consciously register hunger or satiety, your body is sending a barrage of hormonally-mediated messages that influence these feelings4. But these hormones don’t just play a role in how much we eat; they also dictate how we expend energy, influencing both the “Calories In” and “Calories Out” equations.

Contrary to popular belief, obesity is not simply a result of consuming too many calories. It’s a more intricate hormonal disorder, where the delicate balance of these signaling molecules is disrupted. This perspective shifts the narrative from counting calories to understanding and balancing our body’s hormonal orchestra.

4. Not All Calories Are Made Alike

Even though two distinct foods might contain the same number of calories, they can have different effects on our bodies. Different foods, each with their unique nutrient profiles, influence our metabolism in various ways. Take, for instance, the contrast between consuming 20 calories from sugar and 20 calories from olive oil. When we eat sugar, our blood glucose levels spike, prompting our pancreas to release insulin. In contrast, consuming olive oil doesn’t have a significant impact on either blood glucose or insulin levels.

Insulin is a crucial hormone that our body produces to regulate blood sugar levels. It acts as a gateway, facilitating the transfer of sugar from our blood into our cells, where it can either be used immediately for energy or stored for later. When there’s an abundance of glucose in the bloodstream, such as after consuming sugar, insulin ensures this glucose is absorbed into the cells for energy or storage5. Consequently, consuming 20 calories from sugar might increase the risk of weight gain compared to taking in the same number of calories from olive oil.

Thus, it’s essential to understand that not all calories have the same potential impact on weight.


Achieving a healthy weight goes beyond merely counting calories. Truly understanding and prioritizing your overall health is the key to a sustainable, fit, and lean physique. It’s essential to mindfully consume nutritious foods, stay active, and nurture your mental well-being. The difference truly lies in the complete approach taken.


  1. Orcholski, L., Luke, A., Plange-Rhule, J., Bovet, P., Forrester, T. E., Lambert, E. V., Dugas, L. R., Kettmann, E., Durazo-Arvizu, R. A., Cooper, R. S., & Schoeller, D. A. (2015). Under-reporting of dietary energy intake in five populations of the African diaspora. The British journal of nutrition113(3), 464–472. ↩︎
  2. Camps, S. G., Verhoef, S. P., & Westerterp, K. R. (2013). Weight loss, weight maintenance, and adaptive thermogenesis. The American journal of clinical nutrition97(5), 990–994. ↩︎
  3. National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Food and Nutrition Board; Committee on the Dietary Reference Intakes for Energy. Dietary Reference Intakes for Energy. Washington (DC): National Academies Press (US); 2023 Jan 17. 4, Factors Affecting Energy Expenditure and Requirements. Available from: ↩︎
  4. Schwartz, M. W., Woods, S. C., Porte, D., Jr, Seeley, R. J., & Baskin, D. G. (2000). Central nervous system control of food intake. Nature404(6778), 661–671. ↩︎
  5. Schwartz, M. W., Figlewicz, D. P., Baskin, D. G., Woods, S. C., & Porte, D., Jr (1992). Insulin in the brain: a hormonal regulator of energy balance. Endocrine reviews13(3), 387–414. ↩︎


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