Physical activity may not be key to obesity epidemic
January 6, 2009A recent international study fails to support the common belief that the number of calories burned in physical activity is a key factor in rising rates of obesity.
Researchers from Loyola University Health System and other centers compared African American women in metropolitan Chicago with women in rural Nigeria. On average, the Chicago women weighed 184 pounds and the Nigerian women weighed 127 pounds.
Researchers had expected to find that the slimmer Nigerian women would be more physically active. To their surprise, they found no significant difference between the two groups in the amount of calories burned during physical activity.
"Decreased physical activity may not be the primary driver of the obesity epidemic," said Loyola nutritionist Amy Luke, Ph.D., corresponding author of the study in the September 2008 issue of the journal Obesity. Luke is an associate professor in the Department of Preventive Medicine and Epidemiology at Loyola University Chicago Stritch School of Medicine.
Physical activity is defined as anything that gets your body moving. U.S. government guidelines say that each week, adults need at least 2 ½ hours of moderate aerobic activity (such as brisk walking) or 75 minutes of vigorous activity (such as jogging). Adults also should do muscle-strengthening activities, such as weight-lifting or sit-ups, at least twice a week.
Physical activity has many proven benefits. It strengthens bones and muscles, improves mental health and mood, lowers blood pressure, improves cholesterol levels and reduces the risk of cardiovascular disease, diabetes, breast cancer and colon cancer.
But Loyola research suggests that weight control might not be among the main benefits. People burn more calories when they exercise. But they compensate by eating more, said Richard Cooper, Ph.D., co-author of the study and chairman of the Department of Preventive Medicine and Epidemiology.
"We would love to say that physical activity has a positive effect on weight control, but that does not appear to be the case," Cooper said.
The recent study included 149 women from two rural Nigerian villages and 172 African American women from the west side of Chicago and suburban Maywood.
Adjusted for body size, the Chicago women burned an average of 760 calories per day in physical activity, while the Nigerian women burned 800 calories. This difference was not statistically significant.
Diet is a more likely explanation than physical activity expenditure for why Chicago women weigh more than Nigerian women, Luke said. She noted the Nigerian diet is high in fiber and carbohydrates and low in fat and animal protein. By contrast, the Chicago diet is 40 percent to 45 percent fat and high in processed foods.
Results of the new study are similar to those of a 2007 study of men and women in Jamaica. Researchers from Loyola and other centers found there was no association between weight gain and calories burned during physical activity.
"Evidence is beginning to accumulate that dietary intake may be more important than energy expenditure level," Luke said. "Weight loss is not likely to happen without dietary restraint."
Source: Loyola University
Nov 23, 2009 |
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I recommend The Metabolic Typing Diet for more information.
Just look at their hilarious numbers: Chicago women burn 760 calories, Nigerian women: 800 calories a day.
Do you think Nigerian women go and eat several Big Macs every day? A single Big Mac has 590 calories and over half of your daily value of saturated fat in it:
http://www.nutrit...s/6220/2
Eat 3 of them, plus several servings of potatoes fried in fat (fries), plus several cups of sugar water (coke), and it's no wonder there's an obesity "epidemic".
You eat >2000 calories (and bad ones too, that can't be processed easily and stick around), and burn 760 of them... uh, what do you think would happen? Your body can only poop so much of it out, it's not gonna magically disappear, the laws of physics won't allow it! :-p
You burn calories just sitting, so the actual figure is higher, but it's a shame that the article didn't mention what that was, as that's the most important figure: how many calories did these women use up total per day, and how much did they take in.
What your ancestors adapted to eat 50,000 years ago is the diet you should eat for optimum health.
So eat healthy (fruit, Veggies, etc.. etc..)and exercise.
BTW the occasional Big Mac and fries won't kill you, and if you like them, will make life more enjoyable. If I eat junk, then I exercise more.
It's simple, from the market perspective the best food products are those which not only taste best but also induce people to eat as much of them as possible. The food products today on the market evolved towards that goal so they
1. Contain plenty of easily accessible energy to make them tasty
2. Might have altered nutrient compositions to avoid inducing the feeling of satiety after eating
Now 1 is obvious and it certainly plays a part in the problem but 2 is more complex. I don't know to what extent such tricks are successful and I don't know if there are companies doing it on purpose, but it certainly is a possibility so it should be further investigated in the face of the obesity epidemic.
How tricking satiety could be done, for example let's consider sugars but it is just an example and the same principle can be employed with aminoacids and fats also.
Foods contain various sugars but the two most common are glucose and fructose, lets say that both make food equally sweet but fructose is only 20% as effective at inducing the feeling of satiety. Now lets say natural foods have roughly equal amounts of the two, but thanks to modern processing capabilities we can produce foods with artificially raised fructose content and lowered glucose content. Such foods will be just as sweet and tasty as natural ones but they will be much worse at inducing satiety making you eat much more of them.
Foods altered that way will be more successful from business POV and might even displace their natural versions from the market.
Now THIS IS ONLY A HYPOTHETICAL EXAMPLE, I don't know how fructose compares with glucose in reality or if it's being used that way.
One thing to note is that if such tricks do work the food products will evolve to take advantage of them even if they are not consciously designed to do it, market forces will do the trick either way.
All this means American women who want to be as slim as Nigerian women need to cook their own food from raw products.
I would like to see studies conducted on the quality of foods people eat, especially since this is what this research's conclusion alludes to.
And to the commenter who basically said that it is unfair to compare women in North American women to African women because conditions are so much more harsh in Africa, I will say that your belief is very skewed. Africa is a huge continent and living conditions vary. Nigeria is hardly the hot bed of stressful living conditions. Maybe if this study compared Congolese or Sudanese women to those in Chicago then I would agree.
I'm reminded of a comment a very Western friend of the family made years ago after her rather plump daughter returned from living in Africa looking akin to a stick figure - "If you want to lose weight, go to Africa!" Or at least take up their dietary habits according to this study.
I understand a study like that exists in Australia. It would also be interesting to compare genetic ancestry to diet.
That's my weight goal but I'm a 6'3" male.