The Myth of Calories In and Calories Out for Weight Loss
Most of us probably believe that weight loss is simply about cutting calories. Calories in and calories out are all that matters, right? Wrong. How about just eat less and exercise more? Nope. The calories in and calories out theory argues that if you take in more energy (food) than you expend (through exercise and daily movement), you will gain weight. Yes, you need a caloric deficit to lose weight. There's no getting around the physics of that, but while calories count, they may not be the only factor to consider in your weight loss efforts. While tracking calories and macros can be helpful, it's not an exact science.
If the calories in and calories out only model worked, the fat would melt off at a consistent rate and we'd lose all the weight we want just by cutting calories. The reality is that the amount and type of calories we eat affect the amount of energy that our body expends. Have you ever gone on a diet and lowered your calories just to hit a plateau eating the same number of calories a day? When we restrict calories, the body can defend its weight by lowering its resting metabolic rate. To keep that weight loss going, you may need to continue to lower those calories.
In addition, whole foods take more energy to process and digest than processed foods; and, they are more nutrient dense. A study was done where people ate either a "whole food" sandwich (high grain/fiber bread with cheddar cheese) or a "processed food" sandwich (white bread with cheese slice product) where the calories were the same. The people who are the whole food sandwich expended more calories (energy) after they ate their sandwich than those who ate the processed food product. This means their metabolism was burning at a higher rate.
Think about it, 100 calories of Oreo cookies is not going to have the same effect on the body as 100 calories of salmon. Those cookies will spike your blood sugar and make you "hangry" an hour later. The salmon will keep you satiated and feeling fuller longer. It provides healthy omega-3 fats and protein, but those cookies? No healthy fats or protein in there. What we eat also has an affect on our hormones which can affect how we use or store energy. Ghrelin, your hunger hormone, tells your brain when to eat and when to stop. This can be affected by the food we eat.
How we feel after we eat is important to consider as well. What makes up those calories can determine how we feel. If we eat a 100 calorie snack of cookies, we are not to going to feel as well as we would have if we ate 100 calorie snack of steak. How you feel is important because if what you ate wasn't great for you and you don't feel well (perhaps you are tired or having a blood sugar spike or crash) that may lead to things like cravings and snacking behaviours that are not supportive of long term sustainable weight loss.
We believe that if we cut 3500 calories from our diet that we will lose a pound, but this may not always be the case. Other factors like sleep, body size and stress can have an impact on weight loss. You could have your diet dialed in but if your stress levels are off the charts and you are not sleeping, you may have difficulty losing weight. How much processed food you eat can also have an impact on weight loss (re: the conversation about the metabolic effects of food in the sandwich example above). Those people who eat a processed food diet are more likely to over eat. When matched for macronutrient intake, people who eat more processed foods are more likely to snack and may eat up to 500 additional calories a day than those who eat a whole foods diet. And an interesting thing to know: the calorie count on that box of crackers is allowed to be up to 20% off the mark. That means that the 200 calorie serving could be as much as 240 calories.
In the end, calories do matter, but the quality of food and lifestyle factors like sleep and stress will have an impact on your weight loss efforts. Choose something sustainable and consider how you want to feel.