Popular Conditions & Diets
For years and years, counting calories has been the predominant nutrition conversation. Especially for weight loss, “going on a diet” has been synonymous with eating less, based on the supposedly tried-and-true wisdom that moderating consumption is the only way to lose weight.
However, where the messaging to count calories once had a complete monopoly over every discussion of unwanted weight gain, from personal challenges to the global obesity conundrum at large, that monopoly is no longer.
To be sure, there is still no shortage of voices incessantly doubling down on the mantra that caloric deficit is all there is to weight loss. However, unlike the bygone era where calories reigned supreme, there is now also a plethora of opposing health authorities who say something else. This age-old argument is unlikely to end any time soon.
But really, all nutrition polemics and Twitter feuds aside, the primary problem with advising people to eat less to achieve weight loss is that it just isn’t helpful. North Americans have been told, en masse and individually, to moderate calories and get more exercise for decades. And, fast food chains now dutifully report calorie counts of every menu option so consumers are properly informed. But despite it all, the continues to skyrocket with .
A calorie is a unit of energy. To measure the caloric value of a given food, it is burned in a contained lab environment as scientists measure the amount of heat released.
Overfeeding studies, where subjects are fed thousands of extra calories to examine weight gain, have shown only marginal increases in body weight as more is burned off in other creative ways. Starvation studies have shown the opposite: when the body gets less energy, it expends less. As for exercise, many are still surprised to learn that for all its excellent health benefits, weight loss isn’t really one of them.
Part of the issue, as clearly identified in starvation studies as in miserable anecdotes of ‘going on a diet,’ is hunger: eating less makes you hungry, and moving more makes you hungry. The concept of ‘working up an appetite’ is intuitive for a reason!
A significant issue with caloric thinking is logic: energy balance doesn’t explain causality. We can say that one person consumes and stores more calories than another, but this would be that a rich person is rich because they make a lot more money than they spend or that a room is crowded because more people enter than leave.
Imagine explaining to an alcoholic that the reason they are an alcoholic is that they drink too much. This would come across as some sarcastic joke. It would be a description of alcoholism, but it would do nothing to explain real causality, and as a substitute for advice, it would be useless or even insulting.
And yet, this is precisely the messaging that obese people are provided. In the infinitely more meaningful biological and psychological territory of why someone is compelled to overeat, why their body stores more calories as fat tissue, or what to do about any of it, thermodynamics have little value to offer.
The age-old mantra that obesity is just caloric excess is now so routinely challenged by opposing voices that it is clearly not the overbearing hegemony it once was. Either the calories in, calories out model has been altogether disproven, or the situation is, at the very least, much more complicated.
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This begs the question of whether the entire human population is a lost cause of low willpower—we just can’t seem to stop ourselves from eating too much—or whether the monotonous advice to eat less and move more is itself a dead end.
By the 1980s, North Americans were thoroughly aware of an overarching prime directive to reduce fat intake. While the nutritional guidelines that told us to do so were mainly focused on preventing heart attacks, it was also clearly understood that controlling fat intake and our waistline were one and the same project. Why?
Of course, because of calories: a gram of carbohydrates contains 4g of calories, a gram of protein contains 4g of calories, too, but a gram of fat contains 9g of calories—more than double.
Therefore, any calorie-centric way of moderating food intake will necessarily discriminate against fats. Blue Menus, low-fat dairy, and cholesterol-free packaged foods became fairly synonymous with ‘going on a diet’ or living a healthy, weight-healthy lifestyle.
But it didn’t work. On a population level, it even had the opposite impact: the dawn of the low-fat era marked the dawn of the obesity epidemic with remarkable correlation. They began at the same time.
The calories-in, calories-out model of weight gain, also known as the energy balance model, is premised on the idea that the energy we consume (through the food we eat) minus the energy we expend (through physical activity) is equal to the body fat we accumulate.
This perspective assumes energy coming in and energy going out are independent of one another. It assumes that we could spend more calories through exercise and take less by eating less food, putting ourselves in the famous ‘caloric deficit,’ and confidently expect to lose a predictable, mathematically calculable amount of weight.
However, the human body is an intricately regulated system- it doesn’t just pour extra calories into fat stores. Energy from food is used in many ways beyond physical movement, most of which are involuntary. These include heat production, mental activity, heart rate, detoxification, digestion, and breathing. Such sophisticated homeostatic mechanisms explain why many people can take in ‘extra’ calories without gaining unwanted weight.
This is also why reducing caloric intake can lead to reduced caloric output: the body will naturally use less energy in a variety of subtle and creative ways when it is receiving less.
Of course, natural regulation does have limits: anyone force-fed enough will gain some weight, and anyone starved will lose some. This is the truth that calories offer, the proof of their relevance. But how relevant is that fact in the real world, where humans have a choice over their consumption patterns?
What people who struggle with unwanted weight gain and those who stay effortlessly slim no matter how they feast have in common is the body’s thermostat-like mechanism that keeps them at a seemingly predetermined set point. When the diet (or the experiment) is over, they generally return to their natural range.
When the body uses more energy, it calls for more through hormonal hunger signals. The prescription to eat less and move more is almost definitely a prescription for feeling constantly unsatisfied.
This can be downright torturous and places all the emphasis on the individual to evoke herculean willpower to override their natural impulses. They may feel like a failure for being unable to override their humanity when, really, they were set up to fail.
Calories are units of energy descending from German physics experiments in the 19th century that were carefully conducted in closed mechanical systems. However, they do not account for a system like a human body in free dialogue with its surroundings. And they certainly don’t account for hormones; while eating may be a free, conscious decision, the impulses that make us want to eat (hunger) and abstain from food (satiety) are governed by hormonal cues that caloric thinking just can’t explain.
A perfect example of hormonal influence is insulin. Physicists were measuring the calories of different foods long before we understood insulin. Since then, we have learned that elevated insulin makes it difficult to mobilize and burn fat stores in the body, a truth that underpins another conception of obesity called the carbohydrate-insulin model.
While there is evidence for and against the carb-insulin model, it does at least offer an explanation of why some people store more energy in their bodies than others based on what they eat.
The million-dollar question, obviously, is why some people struggle with obesity, and others don’t. A cruel irony is that while energy balance is presented as a fundamental law of thermodynamics, it inevitably leads to the more intangible and psychological question of why some people lack the willpower to control themselves. It is essentially victim-blaming cloaked in science-speak.
A more recent and humane line of thought points the finger not at people but at processed foods, which are increasingly accused of hijacking our reward centres to addict us or trick us, into overeating. However, this admits a crucial contradiction to strict energy balance thinking, which is that what we eat matters, not just how much.
To be sure, some people do win in the calorie-counting field, becoming independently capable of portion control combined with exercise to control their weight. However, these individuals are the exception, not the rule. For the rest, we can either take the fairly cold stance of blaming a great swathe of humanity for failing to apply energy balance or admit that this advice doesn’t really serve the majority of people, most of the time.
It has been thoroughly demonstrated that increased calorie intake and weight gain are not directly related. In some cases, calorie intake can even decrease while gaining weight. Notably, obesity is a significant problem even in places where undernutrition is commonplace. Clearly, calories are not the whole story, and there is something else going on that they can’t seem to explain.
But even though the world of dieting is much more varied than it used to be, caloric thinking is still very much around. While many of us are focused on what we are eating instead of simply how much, others insist that energy balance is all there is.
Fortunately, at least one unifying theory of weight gain has emerged, thanks to a fascinating paper published in the International Journal of Obesity in January 2024. The authors discuss four different models of obesity, including energy balance and the carbohydrate-insulin model. Refreshingly, this perspective holds that differing models of obesity are not mutually exclusive: they all have some truth and utility without necessarily explaining everything.
Perhaps this is exactly the type of nuanced thinking we need to overcome tribalist divides and dogmatic singular explanations. More importantly, perhaps it paves the way for advice that can actually be useful to real people in the real world.
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