Do you ever wonder why you handle dieting much different than those around you?

A few years ago I began a diet along with a friend of mine, let’s call him Dean. We both ate the exact same foods, at the times, and did the same things. Given the similarities in our approach, you’d expect that our reaction to this diet would be quite similar, but it turns out this is often not the case.

While we both provided our bodies with the new challenge of a limited amount of energy aka calories, our bodies had two completely different way to handle this challenge.

I quickly learned that while my desire to move doesn’t drop while dieting, my appetite increases drastically. On the other hand, for Dean, his body’s first reaction to a caloric deficit is to limit his desire to move and exercise. Interestingly, unlike me, Dean’s appetite doesn’t really change much while dieting.

This brings me to the main message in this article:

Our bodies have different ways of reacting to a caloric deficit. It responds by altering either side of the energy balance equation and often both sides at once.

Energy Balance

The energy balance equation is a way of depicting the way our bodies deal with a finite number of calories. Your body wants to maintain homeostasis, and so if energy is off of balance from either side, your body will make adjustments to correct this imbalance. The most obvious example of this is a decrease in metabolism while dieting, but keep in mind, the reverse is also true while gaining weight.

The basic equation looks like this:

  • At bodyweight set point:  Energy In = Energy Out 
  • Dieting:  Energy In < Energy Out  
  • Bulking: Energy In > Energy Out

As you can see, the energy balance equation can be affected by changes in both the energy-in side and the energy-out side. 

Here are some things that your body may do in an attempt to maintain homeostasis:

Energy In

Directly: Increase Hunger, Decrease Hunger, Slow down or speed up digestion to absorb more food 

Indirectly: raise/lower interest in other biological functions such as sex.

Energy Out

Directly: Lowers/Raises Body Temp, Uses Less/More Energy for Digestion (gut motility rate), Produces Less/More Hormones, Changes in non-exercise activity thermogenesis (NEAT) 

Indirectly: Alter Neurotransmitters to Influence Behavior ( e.g. predisposition to be active, etc.)

There are many factors that can influence the energy balance equation, but I’m sure you understand my point– Not only can the body adjust the energy balance equation from either side, but it can do each in an endless combination of ways.

Energy-in vs Energy-out?

Those who explain dieting and losing weight as simply calories in vs calories out are missing this important concept. The body does not work in an isolated system. This means that an adjustment in one area (e.g. change in caloric intake) will lead to changes in another area (e.g. metabolic rate).

While many proponents of the calories in vs calories out model might recognize that this occurs, they underestimate how many factors are at play, as well how strong some bodies fight to balance the energy equation. You shouldn’t suspect anything different from your body–its goal is to keep you from “starving”, no matter what.

Now Let’s Compare My body’s reaction to Dean’s

My bodies first reaction to dieting is to correct the problem from the energy-in side of the equation by means of additional hunger, rather than changing the energy expenditure side of the equation.

Ironically, it may even increase my energy expenditure by creating an increased desire to move. In essence, my body is risking those lost calories with the hopes that this will increase my chance of finding food. For instance, the lower my body fat becomes, the more my desire to run and exercise increases.

My buddy Dean’s body, on the other hand, doesn’t bother with altering the energy-in side but rather limits the energy out. As you can see in this example, the way you respond to a caloric deficit can usually be categorized into one of several subtypes.

Four Subtypes

Hibernator: Fights back against caloric deficit by lowering energy expenditure, but experiences very little change in hunger. e.g. my buddy Dean

Desperate Hunter-Gatherer: Fights back against energy expenditure by increasing the drive for food, even if it increases caloric expendicture in the process. e.g. Me

Unlucky Souls: Get both tired and hungry while dieting.

Unicorns: Get neither tired nor hungry until very low body fat levels. This latter bunch are often the fitness models that seem to be able to stay super lean year-round.

As well as any combination of these to one degree or another.

Not Simply a Fast Vs Slow Metabolism

Don’t make the mistake of simplifying it as those with a fast metabolism vs a slow metabolism because it’s more complex than that. For instance, while one individual might be more resistant to weight loss than another, this resistance may actually allow him or her to maintain normal function in other areas such as appetite or sex drive. The opposite can also be true; another individual’s body may maintain a higher level of caloric burn, but sacrifice those important functions in the process.

I used to think that I would prefer that latter scenario because at least you could stay lean, but after living in that state for six years, I’ve come to the realization that this state can be just as bad if not worse.

Takeaway

We all have a limited number of calories to allocate to the various functions of our body. When we aren’t dieting, there are enough calories to fulfill every function, however, when we diet, our bodies must decide how to best “spend our calories”. Our genetics and our environment are what determine which areas will be affected.

There is however one surefire way to not have negative symptoms from caloric restriction– Don’t Diet!