Fact or fiction? Sex burns a lot of calories. Snacking or skipping breakfast is bad. School gym classes make a big difference in kids’ weight.
All are myths or at least presumptions that may not be true, say researchers who reviewed the science behind some widely held obesity beliefs and found it lacking.
Their report in Thursday’s New England Journal of Medicine says dogma and fallacies are detracting from real solutions to the nation’s weight problems.
“The evidence is what matters,” and many feel-good ideas repeated by well-meaning health experts just don’t have it, said the lead author, David Allison, a biostatistician at the University of Alabama at Birmingham.
Independent researchers say the authors have some valid points. But many of the report’s authors also have deep financial ties to food, beverage and weight-loss product makers — the disclosures take up half a page of fine print in the journal.
“It raises questions about what the purpose of this paper is” and whether it’s aimed at promoting drugs, meal replacement products and bariatric surgery as solutions, said Marion Nestle, a New York University professor of nutrition and food studies.
“The big issues in weight loss are how you change the food environment in order for people to make healthy choices,” such as limits on soda sizes and marketing junk food to children, she said. Some of the myths they cite are “straw men” issues, she said.
But some are pretty interesting.
Sex, for instance. Not that people do it to try to lose weight, but claims that it burns 100 to 300 calories are common, Allison said. Yet the only study that scientifically measured the energy output found that sex lasted six minutes on average — “disappointing, isn’t it?” — and burned a mere 21 calories, about as much as walking, he said.
That’s for a man. The study was done in 1984 and didn’t measure the women’s experience.
Among the other myths or assumptions the authors cite, based on their review of the most rigorous studies on each topic:
—Small changes in diet or exercise lead to large, long-term weight changes. Fact: The body adapts to changes, so small steps to cut calories don’t have the same effect over time, studies suggest. At least one outside expert agrees with the authors that the “small changes” concept is based on an “oversimplified” 3,500-calorie rule, that adding or cutting that many calories alters weight by one pound.
—School gym classes have a big impact on kids’ weight. Fact: Classes typically are not long, often or intense enough to make much difference.
—Losing a lot of weight quickly is worse than losing a little slowly over the long term. Fact: Although many dieters regain weight, those who lose a lot to start with often end up at a lower weight than people who drop more modest amounts.
—Snacking leads to weight gain. Fact: No high quality studies support that, the authors say.
—Regularly eating breakfast helps prevent obesity. Fact: Two studies found no effect on weight and one suggested that the effect depended on whether people were used to skipping breakfast or not.
—Setting overly ambitious goals leads to frustration and less weight loss. Fact: Some studies suggest people do better with high goals.
Some things may not have the strongest evidence for preventing obesity but are good for other reasons, such as breastfeeding and eating plenty of fruits and vegetables, the authors write. And exercise helps prevent a host of health problems regardless of whether it helps a person shed weight.
“I agree with most of the points” except the authors’ conclusions that meal replacement products and diet drugs work for battling obesity, said Dr. David Ludwig, a prominent obesity research with Boston Children’s Hospital who has no industry ties. Most weight-loss drugs sold over the last century had to be recalled because of serious side effects, so “there’s much more evidence of failure than success,” he said.
Online:
Obesity info
New England Journal
Health
Sex to burn calories? Authors expose obesity myths
- Health
-
-
Her Doctor Dismissed the Lump in Her Breast
It was on the weekend of my 25th birthday that my boyfriend alerted me to a lump in my left breast. At first dismissive of his concern, I eventually promised to see my gynecologist. I was due for my annual exam anyway.
-
Tenn. hospital treats drug-dependent babies
He's less than two weeks old, but he shows the telltale signs of a baby agitated and in pain: an open sore on his chin where he's rubbed the skin raw, along with a scratch on his left check.
-
‘Fibro Fighter’ struggles with fatigue, debilitating pain
For some people life is a little more complicated than the normal rushing around with kids, doing errands, being on time for work and other everyday routines that consume most of our waking moments.
-
AP Exclusive: Calif. exchange granted secrecy
A California law that created an agency to oversee national health care reforms granted it broad authority to conceal spending on the contractors that will perform most of its functions, potentially shielding the public from seeing how hundreds of millions of dollars are spent.
-
Drugmakers, health groups bring poor girls vaccine
Two multinational drugmakers are teaming up with top global health groups to protect millions of girls in the world's poorest countries from deadly cervical cancer.
-
Study: Fish oil doesn’t help prevent heart attacks
Eating fish is good for your heart but taking fish oil capsules does not help people at high risk of heart problems who are already taking medicines to prevent them, a large study in Italy found.
-
Most and least-fit states in the U.S.
A new report released by the Centers for Disease Control highlights adult fitness levels based on participation in aerobic and muscle-building activities. Find out which states came in with the fittest and least-fit populations.
-
Bashful? Buy the little blue pill online
Men who are bashful about needing help in the bedroom no longer have to go to the drugstore to buy that little blue pill.
-
FDA wants cancer warnings on tanning beds
Indoor tanning beds would come with new warnings about the risk of cancer and be subject to more stringent federal oversight under a proposal unveiled Monday by the Food and Drug Administration.
-
The Lifefirst family
Young Vincent Karolewics dreamed of becoming a naval fighter pilot.
- More Health Headlines
-
Raw: Aerials Show Path of Oklahoma Destruction
Raw: Widespread Destruction in Moore, Okla.
Raw: Massive Funnel Clouds in Oklahoma
Raw: Japan's WWII Atrocities Under Fire in Seoul
Voters Could Elect LA's First Female Mayor
Raw: Rescuers Pull Tornado Survivors to Safety
Oklahoma Gov: 'Hearts Are Broken' After Tornado
Raw: Walking in a Flattened Okla. Neighborhood
Raw: Rescue Workers Search Oklahoma School
Raw: Witness Describes Scene After Okla. Tornado
Raw: Aftermath of Massive Tornado in Oklahoma
Raw: House Burns After Massive Oklahoma Tornado
Raw: Tornado on the Ground in Oklahoma
Split-second Choice Ended With NY Student Dead
White House Backs 'Shield Law' for Media
Wave of Attacks Kills Scores in Iraq
Pug Life on Display at Wisconsin Festival
Company Promises to Make All Snail Mail Digital
Analyst: Tumblr Fills Void in Yahoo's Offerings
