The Four Components of Metabolism
Metabolism is defined as the bodily processes needed to maintain life. But when you hear the word “metabolism” used today, it’s usually in reference to weight issues. You may hear someone say, “I can’t lose weight because I have a slow metabolism.”
While there’s some truth to this, other factors — such as how much you eat and exercise — play a much bigger role in your weight than your metabolism does. And while it’s true that how much lean body mass you have can affect how many calories you burn at rest, its effect is limited — in part, because you can build only so much lean muscle by strength training.
There are four main components of metabolism which you should be aware. They include:
- RMR (Resting Metabolic Rate)
- Activity Level
- The Thermic Effect Of Food
- NEAT (Non-Exercise Activity Thermogenesis)
Let’s look at each of these individually.
1. RMR (Resting Metabolic Rate)
Resting Metabolic Rate has been discussed earlier. Of importance to remember is that RMR accounts for about 60-75% of total daily energy burn depending upon how active an individual is. Being such a huge component of metabolism, it pays to devote time and energy to keep it optimized.
The higher the RMR, the easier to lose weight and maintain weight in the future. Those who are very active and have a high degree of lean muscle mass will always have a higher RMR value than those who are less active with less muscle. Lean muscle mass determines 74-80% of the RMR value.
2. Activity Level
The daily activity level of an individual also is instrumental in establishing their RMR. Burning calories is the key. This is achieved by exercising at the gym or playing a game of soccer. All of these activities contribute to the daily calorie burn. The more intense an exercise, the more calories it will burn. (Additionally, the higher it may boost the RMR, as noted earlier)
This is the part of the daily energy burn that can fluctuate the most between individuals, and as well as on a day-to-day basis with the same individual. For example, if one day an individual is highly active and the next day they are not, a significant difference in total daily burn rate is seen. Usually, this will account for up to 15-30% of the total energy expenditure for the day.
3. The Thermic Effect of Food (TEF)
The thermic effect of food (TEF) refers to how much energy is used during the process of digestion (the breaking down of the foods eaten). An average mixed diet consisting of a balanced ratio of carbs, proteins, and fats will account for about 10% of the total calorie burn. If a higher protein diet is eaten, it can be assumed the TEF is a little higher. This is because protein-rich food is the most energy-costly to break down and digest. Therefore they will spike the metabolic rate the most.
One reason referring a client to use a high protein diet as a weight-loss strategy results in fewer net calories overall, thus favoring fat loss. It should also be noted that some research does suggest that the thermic effect of food may be higher in those who are already lean compared to those who are overweight. Therefore if an individual is already lean, this may make it easier to stay lean.
4. NEAT
The last component of metabolism to be discussed is referred to as NEAT (non-exercise activity thermogenesis). Essentially, these are movements that individuals make that are not planned but are done spontaneously, often without realizing.
Ever notice how some people cannot stop moving? They have to constantly be pacing, jiggling their foot, tapping their fingers, or so on? This is all classified under NEAT. This element of metabolism is heavily based on genetics. Some people naturally move more, and thus but more calories over the course of the day. Others move less, and as such, burn fewer calories.
Remember, every little bit of activity will add up, so any little movement counts. This generally accounts for about 5% of one’s total daily expenditure, so not very high. In those frequent movers, however, it can be higher, accounting for 10% or more in some instances.
One additional interesting thing to note is that for many people, dieting impacts this. When an individual is on a very low-calorie diet, they naturally tend to move less as their body is trying to conserve fuel. Likewise, when they are eating more food, such as in the case of overconsumption, they will ramp up their NEAT activity, trying to burn off that extra energy.
Those who are the high movers typically ramp up NEAT so much, this may offset some of the excess calories they consume and making it unlikely they experience weight gain. This is a factor that many people overlook, but one that can have a significant influence over body weight.