“Eat less, exercise more”
Most of us have heard it and tried it, but most have failed. We try to eat less and go for a run in the morning, but all that happens is we feel exhausted and lethargic all the time until we quit.
A few people are on the other end, deciding to gain weight they eat and eat and eat but get nowhere.
There is a good reason for this seemingly strange phenomenon. We can have difficulty changing our weight because the human body was brilliantly created to be efficient.
We often think of our daily energy usage as being determined by our size and activity level. While those are important factors, it turns out that the largest factor controlling our energy usage is how much energy is available.
Your activity each day actually has a very little impact on your energy usage. Far more important is how much energy you use by merely being alive, what is called your Base Metabolic Rate, or BMR for short.
Let me illustrate…
BMR Isn’t Static
I am a big guy and one web calculator puts my base metabolic rate as 2786 kilocalories per day, for discussion lets assume that that number is correct. Another calculator says that if I jog 2 miles in one hour I will burn 507 kilocalories.
See Also: What is a Kilocalorie (kcal)?
Assuming that I am sedimentary the rest of the day, my jog represents only about 15% of my energy usage for the day. the other 85% of my energy usage is from my BMR.
Most of us have been taught that BMR is fixed in the short term. We are told that any deficit of caloric intake or any exercise will result in weight loss or starvation and any caloric surplus will result in weight gain. Since every pound of fat equates to about 3500 kilocalories, that means that doing my jog for seven days should result in a one pound weight loss.
Interestingly, there is actually a wide range of caloric intake between starvation or weight loss on the one hand and weight gain on the other. The body was created to regulate its energy usage based on what energy is available. There are a number of biological processes that can turn on and off to regulate your BMR. For example:
- Growing hair and nails
- Healing minor injuries and scars
- Maintaining normal temperature in the limbs
- Creating new biological building blocks (called anabolism)
- Breaking down biological building blocks for energy (called catabolism)
- Recycling cell components (called autophagy)
- Making you feel energized or tired
The body is created to seek balance. So, going back to my example, all my body has to do is reduce my BMR by about 19% and it will completely wipe out any weight loss gained from my hour-long jog.
The next morning when I step on the scale I am tired from the jog, lethargic from the reduction in my BMR, and frustrated because my scale reports zero progress toward my weight goal. Does that sound familiar?
Show Me The Science
“I will praise thee; for I am fearfully and wonderfully made: marvellous are thy works; and that my soul knoweth right well.” (Psalm 119:14)
A study conducted by Dr. Stephen Phinney illustrates this point very clearly. Phinney kept two groups of women in a metabolic ward for five weeks all on very low-calorie diets. One group got no exercise while the other spent an increasing amount of time each day on a stationary cycle. The two groups were found to lose weight at the same rate whether they exercised or not.
You see, God made our bodies to be efficient. In times of deprivation, we adapt by reducing energy levels and putting off tasks like growing nails. In times of plenty, we get around to things that take a lot of energy like rebuilding and renewing our internal organs.
And so I will join the psalmist in declaring, “I will praise thee; for I am fearfully and wonderfully made: marvellous are thy works; and that my soul knoweth right well.” (Psalm 119:14)
- Effects of aerobic exercise on energy expenditure and nitrogen balance during very low calorie dieting https://www.metabolismjournal.com/article/0026-0495(88)90011-X/abstract