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Busted: Debunking the most contentious weight loss myth once and for all

When it comes to healthy, sustainable weight loss, is the old theory it's simply about "calories in, calories out" true?
When it comes to healthy, sustainable weight loss, is the old theory it's simply about "calories in, calories out" true? Health and fitness expert Kelsey Ellis says it's more nuanced, as she busts this top weight loss myth.

A 2021 survey from the Agri-Food Analytics Lab at Dalhousie University, reported that 42% of Canadians have unintentionally gained weight during the pandemic. Chances are, like many Canadians this past year, you’ve considered pulling out the scale and setting a goal of getting back to your pre-pandemic body weight.

Before you embark on your weight loss journey, let’s unpack the most contentious, yet basic, weight loss strategy – calorie counting. Is it really the most effective way to lose weight and is it really as simple as calories in versus calories out? Let’s find out.

Just eat less and move more, right?

When you type ‘how to lose weight’ into any search engine, counting calories is likely the first strategy that pops up and looks something along the lines of a simple math equation – calories consumed must be less than calories expended in order to achieve weight loss.

Weigh loss seekers are often encouraged to eat less and move more to create a calorie deficit. But this process is often oversimplified and misguided because there are a number of factors that can influence your body’s energy balance. Calorie consumption aside, hormonal imbalances, metabolic disorders and psychological factors such as stress and sleep quality play a large role in weight management.

What role does absorption play?

Even if we remove the influence of hormones, stress and sleep from the equation, calorie trackers themselves are largely inaccurate. On average they can be off as much as 20-30% due to large margins of error. Whether that be because either the user under or over estimates their portions or that in general, it is nearly impossible to detect the energy of food with complete accuracy. Even if you were to weigh and measure every bite of food you ate, there would still be a discrepancy in their true caloric value.

While in theory two medium-sized apples of equal weight should have the same energy; variety, age and soil quality can impact the nutritional level and quality of each one. No two apples are the same (unless they were genetically engineered to be of course).

Even if you were able to perfectly detect the nutritional content of a food before you ate it, there is no guarantee that it will be fully digested and absorbed by your body. Each person’s body varies greatly in terms of energy absorption largely due to the genetic makeup of our microbiomes (ie. gut bacteria), age, medication use and exposure to chemical compounds that deregulate absorption of other nutrients.

Food types and the way foods are prepared can also influence their bioavailability and absorption. Acidic foods tend to absorb more slowly while low fibre foods absorb much quicker. Cooking, blending or chopping foods can also change the speed and quality of their absorption. For example, if you were to record a whole banana as part of your smoothie into your food tracker, this would be slightly inaccurate as the calories absorbed from the blended banana would be different that those of a banana in its whole form.

So, does calorie counting work?

Maybe, but not as well as you might think due to the inconsistent nature of it. If you’ve had calories in versus calories out as the most powerful weight loss strategy drilled into your head for years, it’s important to be aware of its limitations. It’s easy to feel like you’ve failed at something so simple when in reality, there is a lot more going on behind the scenes.

Focusing on healthy lifestyle changes such as improving your sleep quality, eating more nutritiously (in terms of quality instead of quantity) and engaging regularly in low intensity exercise can be a more sustainable and effective approach to weight loss long term.