Study provides new evidence that exercise is not key to weight control

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Credit: Peter Griffin/Public Domain

An international study led by Loyola University Chicago is providing compelling new evidence that exercise is not the key to controlling weight.

Researchers who studied young adults of African descent from the United States and four other countries found that neither physical activity nor were associated with . The study is published in the journal PeerJ.

"Our study results indicate that physical activity will not protect you from gaining weight," said lead author Lara R. Dugas, PhD, MPH. Dugas is an assistant professor in the Department of Public Health Sciences of Loyola University Chicago Stritch School of Medicine.

Physical activity has many proven health benefits, ranging from reducing the risk of heart disease, diabetes, and cancer to improving mental health and mood. People who are physically active tend to be healthier and live longer. But while physical activity burns calories, it also increases appetite, and people may compensate by eating more or by being less active the rest of the day.

Some experts have suggested that a decline in physical activity, especially in the workplace, has been a key contributor to the obesity epidemic. But research such as the new Loyola study, in which physical activity is objectively measured and participants are followed over time, has not found a meaningful relationship between weight gain and physical activity.

The Loyola study is one of the primary outcomes of the Modeling the Epidemiologic Transition Study (METS). Researchers followed 1,944 adults aged 25 to 40 living in five countries: the United States, Ghana, South Africa, Jamaica and Seychelles (an island country east of Africa). The American participants live in Maywood, Illinois, a suburb of Chicago. Participants are predominantly of African descent and represent a broad range of social and economic strata. Principal investigator of METS and senior author of the Loyola study is Amy Luke, PhD, professor and vice chair of Loyola's Department of Public Health Sciences.

Previous research has found that when people are asked about their physical activity, they tend to overstate the amount they do. To provide a more objective measure, participants wore tracking devices called accelerometers on their waists for a week. The devices measured the wearers' energy expenditure and step count. Researchers also measured participants' weight, height and body fat. After an initial exam, participants were asked to return after one and two years.

At the initial visit, Ghana participants had the lowest average weights (139 pounds for both men and women) and Americans averaged the highest weights (202 pounds for women, 206 pounds for men). Ghanaians also were fitter than Americans. Seventy-six percent of Ghanaian men and 44 percent of Ghanaian women met the U.S. Surgeon General's physical activity guidelines, while only 44 percent of American men and 20 percent of American women met the guidelines. The guidelines recommend doing at least two and a half hours of moderate-intensity aerobic exercise (such as brisk walking) per week.

Surprisingly, total weight gain in every country was greater among participants who met the . For example, American men who met the guidelines gained a half pound per year, while American men who did not meet the guideline lost 0.6 pounds.

Researchers did not find any significant relationships between sedentary time at the initial visit and subsequent weight gain or weight loss. The only factors that were significantly associated with weight gain were weight at the initial visit, age and gender.

The study was funded by the National Institutes of Health. It's titled "Accelerometer-measured is not associated with two-year weight change in African-origin adults from five diverse populations."

In addition to Dugas and Luke, other co-authors of the study include Liping Tong, PhD, Ramon A. Durazo-Arvizu, PhD, David A. Shoman, PhD, Guichan Cao, MS, and Richard S. Cooper, MD, all from Loyola and researchers from the University of Wisconsin-Madison, Kwame Nkrumah University, Lausanne University Hospital, Seychelles Ministry of Health, University of West Indies, University of Cape Town, University of Cambridge and Norwegian School of Sport Sciences.


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Activity trackers are ineffective at sustaining weight loss, study finds

More information: Lara R. Dugas et al, Accelerometer-measured physical activity is not associated with two-year weight change in African-origin adults from five diverse populations, PeerJ (2017). DOI: 10.7717/peerj.2902
Provided by Loyola University Health System
Citation: Study provides new evidence that exercise is not key to weight control (2017, February 1) retrieved 22 February 2019 from https://medicalxpress.com/news/2017-02-evidence-key-weight.html
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Feb 01, 2017
Does anyone but me think this is junk science as a result of "publish or perish"? This study has to have bias in it somewhere.

Feb 01, 2017
@JamesG
One thing wasn't mentioned but should be mentioned by this article is that food will provide you with more calorie than the calorie you can burn thru exercise. So the only way to lower your body weight is to eat less, that's the only way.

Feb 01, 2017
This comment has been removed by a moderator.

Feb 01, 2017
"But while physical activity burns calories, it also increases appetite..."

.....well who'da thunk? DON'T EAT THE COMPENSATING CALORIES demanded by increased appetite after exercising!!!!!

I have lost as much as 10 pounds in 2-3 days simply from being too busy to come back to the house to eat lunch because I was so busy cutting firewood at the far end of our property 1/2 mile away, eating was too much of a bother to take the time for. I fill up on water or lemonade to keep hydrated & eat a granola bar & I make it through a busy day like this never thinking about my appetite. The thing is, it is true weight loss, it sometimes takes me two weeks to get the weight back because I was burning calories from the fat content of my body & not from food I was ingesting.

All anyone needs to do is balance their calories & your body figures it out without any input from your appetitte.

Feb 01, 2017
@xponen -- You got it buddy. I am a big believer in exercise, but the gym owners won't tell you that eating less is the only way to lose weight. I think exercise is pretty much a wash as far as helping, because it does increase appetite, but also increases endorphins and neurotransmitters that might help with willpower.

Feb 01, 2017
In other words the starving can do just as much work as the well fed because the amount of calories you burn has no significance. Elite athletes, who typically eat two to four times as much as normals and don't gain weight, are not staying slim through their exercise and the sudden weight gain they experience when they retire from elite sport is just a coincidence.

When you are due to work more you need not eat more, or anything at all for that matter, because according to the article there is no relationship between exercise and weight ~ weight is entirely proportional to what you eat and apparently has no relationship to the energy you burn, so as long as your weight is between max and min by BMI you need not bother eating or changing your diet with work load...obviously athletes and heavy labouring workers have been misguided for these past few centuries...

For their next article they might address the question "do we really need to breathe?

Feb 02, 2017
@JamesG
The only way to lower your body weight is to eat less, that's the only way.


Totally agree! Self-discipline is needed. And this way can be very, very difficult.


Feb 02, 2017
Totally agree! Self-discipline is needed. And this way can be very, very difficult.
......from the tone of your post you must obviously be someone who has firsthand experience with this being so "difficult".



Feb 02, 2017
In other words the starving can do just as much work as the well fed because the amount of calories you burn has no significance. Elite athletes, who typically eat two to four times as much as normals and don't gain weight...


Try exercising as much as elite athletes and you'll see why.

Compare and contrast: you have 2x50 lbs weights or about 45 kilos. You bench-press it up by 3ft ~ 90cm and repeat it 2 x 12 times. How much work have you done?

The potential energy gain of the weight is E=mgh which comes out as ~398 Joules per lift, times 24 is ~10 kJ which is one small bite of a Mars bar (938 kJ per 53 gram bar)

Even if you take the metabolic efficiency into account, all the "fat burning for repairs" and multiply the energy consumption by 4x, one set is still just half a Mars bar. You need to do a tremendous amount of work to burn significantly more energy.

A person can easily eat much more than they are capable of working off. You just run out of hours in a day.

Feb 02, 2017
"while physical activity burns calories, it also increases appetite, and people may compensate by eating more or by being less active the rest of the day"

-which is common behavior among hunter gatherers. The chase, the kill, the feast, the nap.

"American men who met the guidelines gained a half pound per year, while American men who did not meet the guideline lost 0.6 pounds"

-It does not say whether this was from muscle, which weighs more than fat.
only way to lower your body weight is to eat less, that's the only way
I think research into the gut biome is going to tell us a lot about how we use the stuff we ingest, why we seem to want more of it than past gens, and why we are fatter than them.

Tropicals generally eat more sugary, fatty foods but in the wild there is less of it to eat. Their gut biome adjusted to make the most of what they ate, and to store the excess because the supply was intermittent.

Biomes can be transferred and inherited.

Feb 02, 2017
The potential energy gain of the weight is E=mgh which comes out as ~398 Joules per lift, times 24 is ~10 kJ which is one small bite of a Mars bar (938 kJ per 53 gram bar)
Numbers are nice but they don't take into account whether excess food is stored or expelled. This depends in part on whether the gut biome is configured to digest it efficiently or not.

If it is used to digesting complex carbs and proteins instead of fats and sugars, it will pass this stuff without digesting it.

Feb 02, 2017
Saccharomyces boulardii and bifidobacterium longum in supplement form are thought to help adjust the gut biome to displace the biota that favor simple fats and sugars.

Feb 06, 2017
Numbers are nice but they don't take into account whether excess food is stored or expelled. This depends in part on whether the gut biome is configured to digest it efficiently or not.


Human digestive efficiency is fairly good. What you don't digest the bacteria tend to turn in to gas and stomach cramps. "Expelled" food tends to mean diarrhea or greasy stool in practice, which I suppose is a fairly regular event for people who overeat.


Feb 07, 2017
@Eikka
There's also anecdotes of runners accidentally defecate during running. Apparently the motion during running help with "expelling" food.

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