Search Weight Loss Topics:




Jan 1

In Losing Weight, What is More Effective, Exercise or Fewer Calories? – American Council on Science and Health

Of course, anyone that has used these measures will tell you that at some point, the weight doesnt continue to be lost, we plateau, and our bodies adjust to their new circumstances. That adjustment reflects the other science of energy expenditure, the constrained energy model simply put, our bodys metabolism redistributes its energy resources seeking to maintain a set energy level.

A new study in Science Advances seeks to identify which is correct, additive, or constrained.

Some quick background

Our total energy expenditure serves to fuel our growth, reproduction, body maintenance, repairing cells and fighting off infections, and physical activity. Physical activity is active energy expenditure (AEE); all the other energetics can be summed as our resting energy expenditure, REE.

TEE = REE + AEE

REE can be measured by our oxygen consumption and carbon dioxide production while resting. TEE can be measured using double-labeled water (DLW), water that uses heavier isotopes of hydrogen and oxygen that can be traced. [1]

The study

The researchers studied 14 children, age 5 to 12, without medical problems, of an indigenous hunter-gatherer tribe, the Shuar, of Ecuador. Their homes are not accessible by road, there is no running water or health clinics, and electricity is both limited and intermittent. Energetics of children from high-income countries came from published DLW studies of 20 children, ages 5 to 6 in the US, and an additional 20 children, age 7 to 9, from Northern Ireland. Accelerometers, think Fitbits, were used to capture the activity of the Shuar children, the movement of the Western cohort was obtained from studies of Canadian children.

These findings are supportive of a constrained model; you cannot efficiently and equally exercise away what you swallow. The Shuar children spent 72% of their energy on their resting needs, compared to 58% for the control kids. Neither the active energy expenditure nor physical activity were reliable measures among these active children. Where did that additional resting energy go?

It was not a difference in body composition, nor were there high thermoregulatory expenditures; after all, the Shuar were in the tropics. Much of the difference went to fueling the immune system. They found that higher environmental pathogenicity, as exemplified by elevated levels of IgG, the most common class of circulating antibody in humans, could account for some of the resting energy expenditure. Other factors could include the energy cost of movement; it takes more energy to move a fat child than a thin one, as well as circadian alterations in resting energy expenditure, which are higher in industrialized cultures.

There are many pieces of the study that can be picked upon, but the data moves us towards an energy-constrained system, and constraints with adaptation are the hallmark of evolution.

Exercise is essential for our health, so that remains in the mix. But what the study suggests is what we eat has a greater effect on our energy balance than how active we are. So, if you are looking for a new years resolution, consider decreasing portion size as a higher priority than the 500 additional calories you burn walking 10,000 steps especially if those steps take you past the donut shop. After all, you are exercising more and deserve a treat.

[1] For those who want a more satisfying explanation, see thisWikipedia entry.

[2] That would equate to walking at 4mph or riding a bicycle at 10-12 mph.

Source: Constraints and trade-offs regulate energy expenditure during childhood Science Advances DOI: 10.1126/sciadv.aax1065

Excerpt from:
In Losing Weight, What is More Effective, Exercise or Fewer Calories? - American Council on Science and Health

Related Posts

    Your Full Name

    Your Email

    Your Phone Number

    Select your age (30+ only)

    Select Your US State

    Program Choice

    Confirm over 30 years old

    Yes

    Confirm that you resident in USA

    Yes

    This is a Serious Inquiry

    Yes

    Message:



    matomo tracker