Metabolism

What is metabolism, the easiest way to explain it is the fire within. Metabolism is the sum of the chemical reactions that occur within each cell of a living organism and that provide energy for vital processes and for synthesizing new organic material.

So what does all this science mumbo jumbo means?

The best way to describe it is if food is fuel and your metabolism is the engine, how well does that engine utilize that fuel. Back in the day of hunter-gatherers, you wanted a very efficient engine operating under a deficient food intake. Resources were limited, and food was not guaranteed, much less having three meals a day with snacks.

A tribe in Tanzania, the Hadza tribe, still hunt and gather food for their survival. They are active from sun up to sundown, hunting, and gathering. A recent study found that the average calorie burn of an adult male was about 2,600 Calories. Yes, that is pretty close to my maintenance calories, and I am sedentary for my job.

High-Efficiency Engine Vs. Low-Efficiency Engine

The study concluded that the human metabolism is very malleable; it adapts for survival. Hormone secretion changes to adjust to the new environment; hormones are chemical messengers that help regulate processes in our bodies. Everything works in harmony to ensure your survival.

There are stories about POWs that survived on as little as 500 Calories a day. Notice the word there survived; we need to learn how to THRIVE.

There is much talk about a broken or slow metabolism. So what does this mean exactly? A slow metabolism can be considered a point where your calories to gain weight are at or below your Total Daily Energy Expenditure (TDEE) or even in a worse spot below your RMR. Before I continue, let me define what TDEE is. To calculate TDEE, you first need to determine your RMR Resting Metabolic Rate. RMR is the energy your body needs to survive if you slept all day, no activities. To calculate this value, we will use the Mifflin St Jeor:

Men: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5 

Women: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161

To get to TDEE, we have to have an activity multiplier. In simple terms, if you have a sedentary job, your multiplier is 1.2, and if you are a highly active person plus having a very physically demanding job, 1.9. There is a crude way to the same approach, get your daily calories and divide by your weight. If the number is below 12 and you gain weight, there is room to improve your metabolism.

What causes a slow or broken metabolism?

First off, your metabolism is not slow or broken. It is doing what it suppose to do with the inputs we are giving it. Those inputs are the calories we eat and the activity we do. Imagine losing weight and creating the calorie deficit; you start cutting down your calories and doing long steady-state cardio sessions (i.e., running). Then you get to a plateau. Naturally, you start doing more and eating less. Before you know it, you constantly reduce calories and increase activities for months and ends. In this scenario, the metabolism would ramp down for survival under TDEE or even RMR.

It's all fine and dandy but now what does it mean to me? 

If we bring back the analogy of the engine. Let's hypothetically say that your metabolism has slowed down that eating at RMR, you gain weight. This would be the equivalent of your buying fuel, and they sell it by the gallon. You buy two gallons, but your engine only uses 1.5 gallons, now that extra half a gallon goes on reserve, in the form of fat, due to the scarcity of fuel.

In the opposite scenario, your metabolism is at nominal TDEE. You buy fuel for your engine, and you buy 5 gallons of fuel, and your engine uses 4.5 gallons; now that extra half a gallon has a more minor impact because the engine will burn through fuel due to the higher demands of the engine. That additional half-gallon will be used regardless, stored as fat and/or glycogen.

The storage of the additional fuel as fat or glycogen is dependent on the type of exercise used to maintain your body composition. Low-intensity steady-state cardio is a fat-fueled (oxidative) activity in the body that will do what it can to be more efficient at this activity. Your body will adapt by eliminating muscle, as it is not conducive to the training and a very expensive (calorie-wise) tissue to maintain. In return, it will focus on storing fuel for the activity in the form of fat. 

This adaptation happens by building more extensive storage of glycogen, more muscle. In comparison to a glycogenic exercise, sprinting. The glycogenic fuel activity will last the most 80 seconds of continuous effort. 

Below is the perfect visual example of a marathoner and a sprinter.

Marathoner (smart car) vs Sprinter (4x4 Truck)

We can draw a clear idea of what steps will be needed to recover the metabolism. For the sake of simplicity, let's take the example from above, chronic under eater, and the only form of exercise is long intensity steady-state cardio. The obvious thing to do is counter-intuitive: start increasing the daily calories. The degree of increase would be determined by the state of the metabolism and the rate at which the client would like to get back to nominal, eating at TDEE and not changing weight. Having the awareness upfront that weight gain is very likely to happen during this process. In parallel, the exercise will be addressed by eliminating the LISS activities and replacing them with weight training. 

In other words, we are in the process of changing the capacity of the fuel tank and the engine itself. 

The time of metabolic restoration will be proportional to chronic undereating and overtraining. 

Those two items are the main items that will get your metabolism restored as a fuel-burning machine. Granted, there are more details in the calorie prescription, such as macronutrient balance, stress management, and recovery. 

In modern life, where food is very accessible, what kind of engine would you like to have?