Calories and Energy Balance
Energy balance and thermodynamics is the primary factor involved in increasing, maintaining, and decreasing body fat. When you look at the full energy balance picture, it helps explain why the simple idea of calories in vs calories out can actually be complex, and why different people of the same size may have different calorie needs. Sometimes we hear that bodies are machines. But we are much more than that. We are multifaceted systems that have the amazing ability to self-regulate and respond dynamically to external and internal factors. So, the following information starts out seeming simple, but as you continue to read about the factors involved on both sides of the energy balance equation, you'll quickly see why determining an individuals calorie needs is not black and white.
There are two sides to the equation when it comes to maintaining your current body weight:
Calories In —— Calories Out
If those things are equal than your body weight stays the same (but water weight and current food in the system will fluctuate throughout the day and week- so even if you are in a maintenance state, your scale weight will fluctuate by at least a little)
Some people get really worked up about this and say that this isn’t how it works- that there is much more involved then simply Calories in and Calories out. And to a degree, they are very much right. But those other factors they have in mind are all subsets of Calories in and Calories out. Let’s review the factors that affect both sides of this energy balance:
Factors affecting Calories/Energy In
Appetite: this can be greatly affected by your hormones. Thus why many women see a spike in appetite when on their period. Also, when cortisol is elevated your appetite increases. Cortisol will likely elevate when your stress level rises and you are low on sleep. Bottom line: when appetite increases, it’s more difficult to keep control of your food intake.
Environmental Factors: These are often things that effect mindless eating- such as long duration social functions surrounding food, distractions of watching tv and sporting events while snacking, quick food availability at home and convenience stores, etc.
Psychological Factors: hyperpalatable foods are in abundance nowadays. These are foods that are fatty, salty, sweet, and/or with refined carbs. Foods such as donuts, chips, sugar sodas, fries, etc are very calorie dense (low volume, and high calories) and lead us to crave more and provide little nutritional benefits. They tend to actually increase our desire to eat and thus quickly overeat without us knowing (unless we are being very attentive to our daily intake). Also, our mental and emotional state will quickly affect our ability to make good food choices. When depressed, lonely, stressed, we often reach first for the most hyperpalatable foods.
Metabolizable Energy: This is a big factor that can seem to muddle the energy balance equation. But in fact, this is PART of the equation. Every individual metabolizes the food and types of food they intake differently. Meaning- some people have very efficient bodies that USE and absorb more of the food they intake than others. So, ironically, more EFFICIENT bodies may also struggle more with weight loss. Because their body actually digests and metabolizes more of their food than someone else with a less efficient system. Also, some types of food are more digestible than others. A Twinkie, for example, will be quickly used and metabolized by the body (so good for quick energy but not much else!). Wh