You've probably heard that weight is all about "calories in, calories out" throughout your weight loss journey. This theory is based on the idea that you're bound to lose weight if you burn more calories than you eat. From zero-calorie sweeteners to 100-calorie snack packs found in the grocery store aisles, it's hard not to buy into what the food industry is trying to sell us when it comes to this concept. Although the leading cause of weight gain is an imbalance in calories consumed and calories burned, it turns out that this notion of 'calories in, calories out' only addresses one small piece of the puzzle. Weight isn't determined by the number of calories you eat but by how they are absorbed by your body.  The two important factors at play here are your hormones and metabolism. Here are four reasons why weight loss is more than calories in and calories out.

Are 100 calories of broccoli the same as 100 calories of Cheez-It crackers? Not exactly, and here's why: All foods are made up of macronutrients (also known as macros) – protein, fat, and carbs. Your body weight will fluctuate when you consume too much or too little of each macro, even if the calorie count remains the same. It turns out that carbs, proteins, and fats are all converted into energy at different rates.

How you absorb and use energy from your diet depends on what you consume and your body's ability to digest certain foods (hint, hint, gut health). For example, refined or "fast carbs" (like bread, cookies, and cake) take the least amount of energy for your body to burn as fuel, so consuming too many of them can lead to excess weight gain and a slower metabolism.

It’s clear that certain foods can have a significant impact on your metabolism. Ever heard of the hormone known as insulin? Insulin regulates your metabolism and the processes that provide energy to your body.

When your body doesn't effectively absorb energy from the foods you consume, those excess calories are carried into the bloodstream and stored as fat in places you don’t want them (like your liver, skeletal muscle, and pancreas). This has a negative impact on your blood sugar levels and insulin function, which leads to excess weight. When more fat is being stored than used, weight gain happens—which is often a result of too much insulin, or insulin resistance. 

And now, enter your gut microbiome. Your gut microbiome has many roles, and is responsible for how your body uses insulin. Your gut health can become compromised if your body tries to break down foods it doesn't recognize (such as processed, packaged foods and inflammatory fats). This imbalance in gut bacteria can lead to inflammation throughout your body and further trigger insulin resistance–which we know is not a good combination when it comes to trying to lose weight.

As mentioned, your hormones help to regulate your metabolism.  When your body doesn’t properly absorb energy from the calories you consume, there is an overflow of excess energy that is then stored as fat.  Estrogen, testosterone, and progesterone (your sex hormones) fluctuate at different life stages and can impact the rate at which your body is able to burn calories. Another key player in regulating those metabolic processes (including burning calories) is your thyroid. Hyperthyroidism (an overactive thyroid) is a disorder that occurs when the thyroid releases larger quantities of hormones than necessary, which speeds up the metabolism. This can lead to weight loss, increased appetite, anxiety, and diarrhea, and is correlated with a higher resting energy expenditure.

On the other hand, hypothyroidism (an underactive thyroid), does just the opposite. It is correlated with a lower resting energy expenditure which can lead to unusual weight gain, lethargy, depression, and constipation. Both of these hormonal disorders impact the way your body absorbs calories.

Ever heard the advice "eat less, exercise more"? While creating a calorie deficit can help you achieve weight loss, doing so by exercising alone may not be your best bet, and here's why:

Exercise can significantly contribute to overall long-term health, and when coupled with proper dietary intervention can aid in weight loss as well. However, you can't exercise your way out of poor diet choices, and it's best to instead use exercise as a way to leverage your weight loss and to feel great in your body. 

When you think about your weight care journey, you need to look at the whole picture.  Your hormones, gut health, and metabolism all impact the way your body absorbs calories, and they need to be balanced in order to operate efficiently.  Think about the calories from your food choices as fuel, and choose whole, natural, nutrient-dense foods whenever possible so that these systems can continue doing their jobs.