Why you won't lose weight with exercise alone

-

 

Why you won't lose weight with exercise alone





Exercise by itself isn't always enough to take off the weight. Now, evidence reported in the Cell Press journal Current Biology on January 28 helps explain why our bodies adapt to higher activity levels so that people don't necessarily burn extra calories even if they exercise more.

The results suggest it's time to rethink the effect of physical activity on daily energy expenditure, the researchers say. They are also a reminder of the importance of diet and exercise in supporting weight loss goals.

"Exercise is really important for your health," says Herman Pontzer of the City University of New York. "That's the first thing I mention to anyone asking about the implications of this work for exercise. There is tons of evidence that exercise is important for keeping our bodies and minds healthy, and this work does nothing to change that message. What our work adds is that we also need to focus on diet, particularly when it comes to managing our weight and preventing or reversing unhealthy weight gain."

After a few months, people who start exercise programs to lose weight often see a decline in weight loss (or even a reversal). Large comparative studies have also shown that people with very active lifestyles have similar daily energy expenditure to more sedentary populations.

Pontzer says this really hit home for him when he was working among the Hadza, a population of traditional hunter-gatherers in northern Tanzania.

"The Hadza are incredibly active, walking long distances each day and doing a lot of hard physical work as part of their everyday life," Pontzer says. "Despite these high activity levels, we found that they had similar daily energy expenditures to people living more sedentary, modernized lifestyles in the United States and Europe. That was a real surprise, and it got me thinking about the link between activity and energy expenditure."

To explore this question further in the new study, Pontzer and his colleagues measured the daily energy expenditure and activity levels of more than 300 men and women over the course of a week.

The data they collected saw a weak but measurable effect of physical activity on daily energy expenditure. Further analysis showed that this pattern was only held among subjects on the lower half of the physical activity spectrum. People with moderate activity levels had somewhat higher daily energy expenditures--about 200 calories higher--than the most sedentary people. But people who fell above moderate activity levels saw no effect of their extra work in energy expenditure.

"The most physically active people expended the same amount of calories each day as people who were only moderately active," Pontzer says.

The researchers say it's time to stop assuming that more physical activity always means more calories. There might be a "sweet spot" for physical activity--too little and we're unhealthy, but too much and the body makes big adjustments to adapt.

Pontzer and his colleagues now plan to study how the body responds to changes in activity level. They'll start by looking for other changes--for example, in immune function or the reproductive system--that might explain how the body adapts to greater physical demands without consuming extra calories.

Story Source:

Materials provided by Cell Press. 


Comments

Post a Comment

Popular posts from this blog

PEOPLE WITH OBESITY BURN LESS CALORIES DURING THE DAY

-
Image
  PEOPLE WITH OBESITY BURN LESS CALORIES DURING THE DAY Building on prior studies with healthy-weight participants, the new research includes different body sizes.         New research indicates that weight influences how and when bodies burn energy. An Oregon Health & Science University study published in the journal  Obesity  found people who have a healthy weight use more energy during the day, when most people are active and eat, while those who are obese spend more energy during the night when most people sleep. The study also found that during the day, those with obesity have higher levels of the hormone insulin -- a sign that the body is working harder to use glucose, an energy-packed sugar. "It was surprising to learn how dramatically the timing of when our bodies burn energy differed in those with obesity," said the study's first author, Andrew McHill, Ph.D., an assistant professor at the OHSU School of Nursing and the Oregon Institute of ...
Read more

WHAT CAUSES ITCHING, AND WHAT STOPS IT?

-
Image
  WHAT CAUSES ITCHING, AND WHAT STOPS IT?         It can be a relief to scratch the occasional itch, but when itch gets out of control, it can become a severe health problem. How does the body know when to stop? Scientists at UC San Francisco are getting close to an answer. In a breakthrough that could transform how doctors treat conditions from eczema to allergies, they have discovered a feedback loop centered on a single immune protein called IL-31 that causes the urge to itch and dials back nearby inflammation. The findings, published on October 13th in  Science Immunology , lay the groundwork for a new generation of drugs that interact more intelligently with the body's innate self-regulating ability. Previous approaches suggested that IL-31 signals itch and promotes skin inflammation. However, the UCSF team discovered that nerve cells, or neurons, that respond to IL-31, triggering a scratch, also prevent immune cells from overreacting and causing more ...
Read more

A VEGAN DIET IMPROVES CARDIOVASCULAR HEALTH, ACCORDING TO A NEW STUDY

-
Image
  A VEGAN DIET IMPROVES CARDIOVASCULAR HEALTH, ACCORDING TO A NEW STUDY         In a study with 22 pairs of identical twins, Stanford Medicine researchers and their colleagues have found that a vegan diet improves cardiovascular health in as little as eight weeks. Although it's well-known that eating less meat improves cardiovascular health, diet studies often need to be enhanced by genetic differences, upbringing, and lifestyle choices. By studying identical twins, however, the researchers were able to control for genetics and limit the other factors, as the twins grew up in the same households and reported similar lifestyles. "Not only did this study provide a groundbreaking way to assert that a vegan diet is healthier than the conventional omnivore diet, but the twins were also a riot to work with," said Christopher Gardner, Ph.D., the Rehnborg Farquhar Professor and a professor of medicine. "They dressed the same, they talked the same, and they had a banter ...
Read more