What is a calorie?
Calories. You know they exist, but you can’t see them and you’re not exactly sure how to define them either. So that’s where we’ll start.
What is a calorie?
A calorie is the basic unit of measuring energy. According to the law of thermodynamics, energy can not be created or destroyed. It can only be converted from one form of energy to another. Your body uses the chemical energy you consume (food) in calories and turns it into kinetic energy so that you can walk, breathe, and scroll through this post.
Losing weight is just about calories in vs calories out (CICO)….right?
Although nutrition experts on both sides agree that to lose weight one must eat less than is needed to maintain their weight, there is disagreement around ‘calories in vs calories out’. Some claim it’s as simple as “eat less, move more”. On the other side of things, critics say that it’s more complicated than that because CICO does not account for hormone imbalances, insulin resistance, PCOS, and other conditions that affect metabolism.
CICO is an unofficial way to describe energy balance though the systems involved tell a more detailed story. Your brain sends and receives messages with your gut, hormones, organs, muscles, bones, fats, and more to help balance “energy in” and “energy out”. It is necessary to mention leptin and ghrelin while on the topic of energy balance. Leptin and ghrelin are two of the many hormones that affect energy intake and hunger. They both send signals to the part of the brain called the hypothalamus. Leptin, in short, is designed to tell you when you are full and to stop eating. Ghrelin on the other hand, tells us to consume food when we have low energy and promotes fat storage when needed. Many obese individuals suffer from leptin resistance which alters the signaling process. The brain doesn’t respond to leptin signals, so it thinks it’s okay to continually overeat. This makes it easier to overeat and store fat. So it’s not quite as simple as “just eat less”.
The most direct factor that influences “energy in” is food consumed. Indirect factors include appetite, calories absorbed (your body does not absorb everything you consume), and factors such as sleep, stress, mindset, and self esteem. “Energy out” includes energy burned at rest which depends on body size, muscle mass, hormonal status, dieting history, chronic disease (ie PCOS, hypothyroidism etc), genetic factors, age, and sleep quality. This also includes energy burned through exercise, non-exercise activity, and metabolizing food.
If your goal is weight loss and you’re just not seeing results, you need to decrease energy in, and increase energy out. However, there is more to consider. It may require you to dig a little deeper and ask yourself the following:
1. How is my sleep quantity and quality?
2. What is the quality of the food I’m eating?
3. Could I be moving a little more throughout the day? (Ex: park farther away, go for lunchtime walks, take the stairs)
4. Should I consider tracking my food intake via hand portions or measuring?
5. What are my daily stress levels like? Am I incorporating methods to reduce my stress when possible?
As mentioned above there are many factors that we should take into account when discussing calories. Below are two common frustrations my clients have mentioned regarding calories and weight loss:
“I’m tracking my food and I’m eating x amount of calories and I am STILL not losing weight!”
There are a couple of aspects to consider with this complaint:
1. People often underestimate their caloric intake. They underestimate portions, and they don’t track little bites of food here and there throughout the day (hoping that if they forget to track it, it didn’t happen). For example, they took a spoonful of peanut butter thinking it was 1 tablespoon (90 calories), but it was actually 3, so they just tripled the amount of calories they thought they consumed. They also don’t record food measurements at the moment and forget to log it later. Chances are, if they wait to log something it will be inaccurate.
2. People overeat on the weekends. We get it, life is stressful and by the time the weekend rolls around they want to grab drinks with friends. Or they get invited to a favorite brunch spot on a Sunday and just can’t resist. But does all this REALLY make that big of a difference?
As much as I’d love to tell you it doesn’t matter, it does. Let’s say that you’re in a caloric deficit and allotted 1500 calories per day which is 10,500 calories per week. You go out on a Friday night and have a couple drinks, have a big lunch on Saturday, and attend that brunch on Sunday. You consume an additional 4,000 calories Friday through Sunday. You’ve canceled out your calorie deficit bringing your daily calories to 2,071.
3. People will add back in the calories they “burned” during exercise. This is a very common and honest mistake clients will make. The idea of ‘earning’ calories is not only misleading, but it could result in dangerous behavior change because it turns exercise into a punishment. If you workout with the only goal to burn as many calories as possible, you end up exercising for far too long daily, having a potentially damaging effect on your health and relationships and not moving you closer to your weight loss goals. You’d end up exercising all day everyday just to be able to eat, which is unhealthy and unsustainable. Sounds unreasonable doesn’t it? Being in a calorie deficit means that you consume less calories than your body needs to maintain its current weight. While resistance training promotes muscle gain, and cardio supports heart health, the foundation or weight loss is consuming fewer calories than your body needs for weight maintenance.
Using the information above as an example, your calories are set to 1500 per day (in a deficit) which we know is 10,500 weekly. You go to the gym and have a great workout and your smart watch says that you burned 600 calories (Which is problematic because fitness trackers are wildly inaccurate in terms of calories burned). You go into your food logging app, and adjust the calories to say 2,100. The math checks out, right? You burned 600 extra calories so now you can have two dinners! Wrong. If you did this 5 days per week, your daily calories would jump to 1,928, so you’d no longer be in a deficit.
“My hormones are out of wack”
People (especially women) think they gain weight simply because of their hormones. They chalk it up to ‘getting older’. You don’t gain weight because of your hormones, you gain weight because your hormones affect your energy balance.
For example, the thyroid hormone (T3) can affect energy expenditure and for people with a low thyroid hormone this can affect BMR up to 25%. (BMR refers to Basal Metabolic Rate which is how many calories you expend at rest). This might mean that for someone who has a BMR of 1600 calories, their true BMR is actually 1200 calories.
All this means is that your hormones are affecting “energy out”. Your “energy in” and “energy out” has changed. IF this is because of hormones, you can make adjustments to your nutrition, exercise, and any other lifestyle changes.
Any hormone that impacts weight loss will do so by changing energy expenditure or energy intake.
As you now realize, calories and weight loss are a complicated story, and I've only addressed a few factors in this post. Nonetheless, I hope understanding the science behind calories, you’ll feel more confident should you choose to start a weight loss phase.
