Why Losing Weight Feels Impossible: The Science Behind Your Struggle

Losing weight is tough, and unfortunately, your body is working against you at every turn. As a biological machine, your body operates according to the laws of thermodynamics, requiring energy and raw materials to function, which is why you need to eat. The energy from food is measured in calories, and you need a specific amount to fuel your internal systems. Your brain processes thoughts, your heart pumps blood, your digestive system processes food, and your immune system defends against threats. Additionally, you use your muscles to move.

The more strenuous the activity, the more calories you burn. For example, an hour of walking burns around 260 calories, moderate swimming burns 430, biking 600, and running 700. If you consume more calories than you expend, your body stores the excess as fat. One kilogram (or two pounds) of fat is roughly 7,000 calories. It seems straightforward: to lose weight, you need to burn more calories than you consume, thus converting fat back into energy.

The Myth of the Workout

We often believe that exercising is a surefire way to lose weight. However, this isn’t entirely accurate. Recent studies have shown that the amount of calories burned through exercise is often less significant than we think.

A few years ago, scientists compared populations in industrialised societies, who typically sit a lot, to hunter-gatherer communities, who are much more active. For instance, the Hadza people in Tanzania walk an average of 9 kilometers a day, engaging in activities like hunting, gathering, and collecting water. Despite their high activity levels, the Hadza burn the same number of calories per day as the average person in an industrialised country: about 1,900 calories for women and 2,600 for men. This paradoxical finding suggests that the total number of calories burned daily is relatively stable regardless of activity levels.

Active people who exercise regularly do burn slightly more calories than those who are inactive, but the difference is often minimal – sometimes as little as 100 calories, equivalent to a single apple. It turns out that your body has a fixed daily calorie expenditure that it aims to maintain, regardless of lifestyle. If you want to gain muscle by lifting weights, you need to eat more to build and sustain that muscle. But overall, your body's total calorie budget remains fairly constant.

Why Your Body Sabotages Weight Loss

When you start working out regularly, your body might compensate by making you less active in other areas of your life. You might take the elevator instead of the stairs, sit more when socialising or sleep longer, effectively balancing out the extra calories burned through exercise. This subconscious adjustment can hinder weight loss efforts.

Initially, if you drastically change your sedentary lifestyle and start exercising without increasing your caloric intake, you will burn more calories and lose weight. However, this effect is short-lived. Over time, your body adapts, reducing the extra calories burned until it returns to its original calorie budget. This adaptation explains why the weight loss from exercise alone often plateaus after a few months.

Why Exercise is Still Important

Your body has a hardwired daily activity budget that evolved when humans had to move a lot for survival. In times of abundant food and voluntary exercise, your body reallocates unused energy to other systems. This can lead to negative outcomes, such as increased chronic inflammation and stress.

When your immune system detects an injury or infection, it triggers inflammation, a crucial response that can cause damage if not managed efficiently. Chronic inflammation is linked to serious diseases like cancer and heart failure. With excess calories available, your immune system may overcommit to inflammation, exacerbating these issues.

Additionally, your body produces hormones like cortisol, the stress hormone. While essential for survival in acute situations, excess cortisol from chronic stress can lead to numerous health problems, including mental health issues. Our ancestors needed this hormone to handle sudden bursts of activity, but in modern sedentary lifestyles, it can be harmful.

Exercise helps restore physical balance, reducing chronic inflammation and stress, improving heart health, and potentially easing depression. While it might not be a magic bullet for burning fat, regular exercise offers significant health benefits and contributes to a higher quality of life.

Why Humans Are So Hungry

Our ancestors had to work hard for calories, sometimes moving long distances to find food. If extra movement burned significantly more calories, it could lead to a cycle of starvation. Thus, humans evolved to move efficiently without burning excessive calories. This efficiency helped ensure survival during times of food scarcity.

Today, the obesity epidemic is primarily driven by overeating rather than inactivity. Humans have evolved to crave calories because of our energy-hungry brains and dependent children. The human brain consumes about 20% of our resting calories, twice as much as our closest ape relatives. This high demand for calories helped us become efficient calorie harvesters, but in modern times, it has contributed to overeating.

In ancestral societies, members would share food, ensuring no one went hungry. This social behavior, coupled with our efficient calorie harvesting abilities, is deeply ingrained in us. However, in today's world of abundant food, this trait has turned against us, leading to overproduction and overeating.

While exercising may not help you lose as much weight as you hoped, it is crucial for maintaining balance in your body and preventing many diseases. By understanding the complexities of weight loss and the role of exercise, you can adopt healthier habits and enjoy a better quality of life.