Understanding Calories

The underlying cause to today’s current obesity epidemic is believed to be an energy imbalance between calories consumed verses calories burned. We are consuming too much food, and we are not moving enough. The prevalence of obesity in Australia is reaching an all-time high, with ‘2 out of 3 Australian adults considered overweight or obese.’ (1) We are told the solution is easy: just eat less, and exercise more. But I don’t think it’s that simple. If it came down to just eating less and moving more, I do not think we would be facing this growing epidemic. According to Professor Richard D Feinman from State University of New York Downstate Medical Centre, ‘different foods affect our bodies in different ways, with different types of food having different metabolic pathways that affect our hormones that regulate our appetite.’ (2) Proponents of this ‘calories in versus calories out’ way of thinking assume that the only thing that matters when it comes to weight loss is calories. It completely disregards the ‘metabolic and hormonal impact’ (2) food has on our us. When it comes to weight loss and maintenance the different types of foods we consume in our diets are just as important to consider, as is the amount of calories we are digesting. Calories are the most basic form of food that makes up our macro and micro nutrients... Simply put, a calorie is a measure of energy, where “energy is defined as the capacity of a system to do work.” (3) Our bodies need energy to perform every day functions such as eating and digesting food. Different types of calories offer different amounts of energy, with differing capacities for work. Not all calories are created equal. Carbohydrates, Fats and Proteins are our main macronutrients. With our bodies processing these macronutrients in distinct ways, these foods affect our ability to gain, lose and manage our weight in contrary ways. Let me explain. Our metabolic pathways require more energy to digest protein than it does the fats and carbohydrates. ‘Our bodies use about 30% of its energy to break down 100 calories of protein, just for digestion, compared to only 10% of its energy to digest 100 calories of carbohydrate.’ (4) Furthermore, carbohydrates use less energy to be stored, compared to protein, and therefore we are more likely to store carbohydrates as energy. Protein costs the body more energy to store. 100 calories of one type of macronutrient can therefore end up with a higher net of total calories in the long term, as it may be stored more easily. It is important to also note that the effect of calories can depend on other lifestyle factors, such as what they are eaten with, and when they are eaten, as well as genetics and overall health. Consuming different macronutrients can affect our weight more so than just restricting them. In a study by Nordmann AJ et al (2006), the Cochrane Collaboration search strategy was used to identify trials comparing the effects of low-carbohydrate diets versus low-fat diets in overweight individuals. The participants were all on the same total calories, but with different types of calories. Those assigned to low-carbohydrate diets lost more weight than those on low fat diets, with a weighted difference of a loss of 3.3kgs compared to a loss of 2.4kg, respectively. (5) Different types of calories from different sources have different effects on our body, and our metabolic pathways and appetite hormones. Although total calorie intake is essential for weight maintenance, counting calories alone is not always enough for weight loss. 1. AIHW 2015. Australia's welfare 2015. Australia's welfare no. 12. Cat. no. AUS 189. Canberra: AIHW. 2. Feinman and Fine Nutrition Journal, 2004, BioMed Central Ltd. 3. Authority Nutrition 2012-2016. 4. Barr SB, Wright JC. Postprandial energy expenditure in whole-food and processed-food meals: implications for daily energy expenditure. Food Nutr Res. 2010 Jul 2;54. 5. Nordmann AJ et al Arch Intern Med. 2006;166(3):285-293. Contributed by: Tammy Kacev

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