Counting calories is rather imprecise, but is in fact necessary in altering body composition.
Simply put, those aiming to lose fat must consume fewer calories than they expend.
However, this equation is not always as simple as it seems. In order to lose one pound of fat, 3500 kcal must be burned through exercise, food restriction or a combination of both (1,000 calories equals one kcal). Most individuals will track their calories via an app such as MyFitnessPal, as well as their activity levels through heart rate monitors, ultimately hoping to be somewhere south of their maintenance needs for the day. I cannot argue that this is a sound approach to start, but it is not sustainable over the long term, nor is it highly accurate.
What are our energy requirements?
Energy requirements vary person to person, with countless variables such as age, gender, genetics, and goals to account for. If a person wants to find out what they require to maintain their current body weight, they need to first find their basal metabolic rate. Take your current weight, multiply it by 10 and you will get a relatively close number. From there, you multiply your BMR by your daily activity level. Many calculators vary with this equation, but most commonly a sedentary individual would multiply BMR by 1.2, a moderately active person would multiply BMR by 1.5 and a very active person would multiply BMR by 1.75. For a 150 pound moderately active man, his BMR would be around 1,500 kcal (assuming 150 multiplied by 10) multiplied by 1.5 for moderate activity, equating to about 2,250 kcal required daily to maintain his weight.
Where things get complicated
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In theory, the mathematical approach to calories in calories out should provide an easy route to manipulate body composition. However, this couldn’t be further from the truth. Those who claim “a calorie is a calorie” are simply misinformed. The thermic effect of food plays a large role in absorption and assimilation of nutrients. Essentially, every food requires a certain amount of energy to digest and process. Highly processed, nutrient void foods (i.e. chips, candy, soda) require little energy to digest and can be rapidly absorbed whereas fibrous vegetables, animal proteins and other whole foods take a significant amount of energy to process. A 100 kcal handful of almonds will use about 20 percent of its energy to be absorbed, whereas a 100 kcal cookie will only use about 5 percent.
To further complicate matters, nutrition labels are notoriously imprecise. These can be off by as much as 15 percent one way or the other. A 500 kcal snack could contain nearly 575 kcal without you even knowing. In addition, the preparation of food alters its caloric density. Well-cooked meats will contain more calories as they are more highly absorbable in comparison to something like a rare steak. Lastly, calories burned through exercise vary by movement efficiency and your current body weight. If you started training for a marathon as a 200-pound novice, ultimately getting down to 180 pounds and falling into an intermediate category, you may notice a plateau. This is because you burn fewer calories through exercise as your movement efficiency has increased, and you are lighter overall. Caloric needs must be adjusted in conjunction with weight loss in order to continue seeing results.
This may seem overwhelming and rather difficult to quantify, however, the soundest approach to nutrition and body composition change in my opinion is consuming nutrient dense minimally processed foods that satiate you. From there, have a ballpark estimate of your daily caloric needs as well as roughly the amount you are burning through exercise.
If you wish to lose weight, start with a modest 500 kcal daily deficit and work your way from there. To gain weight, an additional 200-300 kcal is a good starting place. The are obviously gross explanations of energy expenditure/requirements in human physiology, however I hope this provides a basis and platform with which you can work from. Thanks for reading as always.
Jimmy Pritchard has a Bachelor in Science in exercise science from Colorado Mesa University and is a certified strength and conditioning specialist through the National Strength and Conditioning Association. He is the director of strength and conditioning at Ski & Snowboard Club Vail. Contact him at 970-331-3513 or jpritchard@skiclubvail.org.
