Calories In, Calories Out: Is It Really That Simple?
Calorie counting — a ubiquitous tool in the world of fitness. However, its ability to fully explain the complexities of weight management is up for debate.
If you've ever considered trying to lose weight, or been around someone who has, then you’ve probably been confronted with the “Calories In, Calories Out” (CICO) equation:
Energy balance = Calories In (calories consumed via food and drink) — Calories Out (calories burned through exercise and the basic processes required ot keep you alive)
This seems fairly straightforward, right? Eat fewer calories (one calorie is formally defined as the energy required to raise the temperature of 1 kg of water by 1°C), lose more weight, right? However, many nutritionists and health experts argue that the CICO approach to weight loss is an oversimplification of a complex phenomenon that incorporates multiple factors that influence a person’s weight.
First, let’s make something clear: I take no issue with CICO. The scientific literature shows that there is a huge correlation between tracking progress and success in losing weight. CICO is a unbreakable law of thermodynamics — in fact, it is the successful underpinning of every diet. It’s been consistently shown in study, after study, after study that a caloric deficit is required in order to lose weight, regardless of the diet consumed.
Clearly, CICO is well supported as the fundamental principle behind weight loss. However, whether its possible to strictly adhere to CICO and whether or not it takes the full picture into account is up for debate.
So what are the issues with CICO?
Calorie metrics are skewed at every stage.
In order for CICO to be effectively carried out, individuals need to be able to accurately gauge how many calories they are burning and consuming. It’s questionable if that’s possible when food regulation bodies such as the FDA allow for a 20% variation on calorie labels — meaning your 100 calorie yoghurt could actually be anywhere between 80–120 calories.
Not only that, but commercially-available fitness trackers are ridiculously bad at calculating the number of calories burnt (with a median error rate anywhere between 27.4%-92.6% depending on the device).
The devices aren’t the only ones to blame though — we are too. People on diets underreport their calories consumed (by an average of 31–63%) and overreport their level of calories burnt via exercise (by as much as 126%!). While this effect is less pronounced in fitness professionals, fitness professionals still underreport by 233 calories on average.
The final nail in the coffin? Resting metabolic rate — which is often used to determine your exact caloric targets via free online calculators — often varies by as much as two/three-fold between individuals, even when age, sex and body mass are controlled for.
If the calorie-counting process is fucked on every level, how can people hit proper caloric deficits?
CICO reduces food to its caloric content.
One of the biggest issues with CICO is that it reduces food purely into the calories they contain. However, calories are not made equal. 100 calories of junk food and 100 calories of a well-balanced meal are going to have wildly different effects on our bodies. In fact, our diet needs to contain a variety of nutrients and vitamins — doing so has many benefits, such as improvements to mental health.
CICO, by focusing only on their caloric content, sidelines the nutritional value of foods. It’s true that you’ll lose weight as long as you’re in a caloric deficit, but depriving your body of key nutrients has many detrimental effects. Losing weight is admirable, but it should be done for your health — not at its cost.
Hyper-focus on calories create a dichotomous thinking style — a significant predictor for weight rebound and development of eating disorders. In fact, we see that calorie counting has strong associations with and exacerbates eating disorder symptomology — a worrying correlation.
While CICO is the underpinning principle of weight management, it has a number of key weaknesses. Whilst CICO can and should be used as a guiding principle, a holistic approach must be implemented that promotes sustainable fitness strategies, a healthy relationship with food, a balanced diet and intuitive/mindful eating habits in order to achieve long-term success.
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