TODAY   |  February 02, 2013

Popular weight loss myths debunked

A new report looks at commonly held beliefs about weight loss, and reveals that age-old assumptions about slimming down could be wrong. “Turns out sex doesn’t burn a lot of calories,” said Dr. Lori Mosca. TODAY’s Erica Hill interviews her.

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>>> if you're one of the millions of people who struggle with your weight, new findings show the problem may not be you. turns out some commonly held beliefs about what it takes to slim down and stay that way are wrong. that's according to a report published in the "new england journal of medicine." dr. lori maska is director of cardiology at new york presbyterian hospital . nice to see you. it's always nice to know it's not our fault, right?

>> absolutely.

>> let's look at some of these commonly held beliefs. and find out whether or not they're true. we hear a lot that a rapid weight loss doesn't stick. if you lose that 100 pounds, chances are you're putting it back on right away, and this can lead to yo-yo dieting s. that true?

>> a lot of research stems back to the 1960s when rapid weight loss had some adverse associations with it. so doctors tend to recommend slower weight loss . but new research really shows that there's tremendous individual variability. and actually some people that have rapid weight loss actually sustain it much longer than those who do not. in fact, i have to tell you in my clinical practice, it really helps people to get a jump-start. you know, they feel good. they get that positive feedback . and they can stay with the program a little bit longer.

>> it's a great motivator personally and when you hear feedback from other people. a lot of times you're told you should set realistic weight loss goals. even if you have to lose 50 pounds, maybe start out with 25 so it doesn't feel so overwhelming.

>> right. and i have to confess, i'm a person that has always promoted realistic goals amongst my patients. but we are a high achieving society. we're all individuals and many of us respond to raising that bar higher. we don't treat our kids all the same, our patients the same, athletes the same. people are motivated in different ways. don't be discouraged. you know, if you really want to set a high goal for yourself, go for it. you might actually be very successful.

>> all right. also, there's a lot of talk about gym class or physical education in schools which we've seen cut in a lot of school districts because of budget issues. there's a belief that these classes can actually lead to weight loss . i find that surprising.

>> well, i'm concerned about this myth. i think that we have to keep in mind and underscore the -- that gym class in their current form, they're not like in the old days when you got to play. many of our physical education classes now are filled with learning rules, writing about how you feel about this sport, you know, we need to ingrain habits in kids early. and even though our research doesn't show that the current form of physical education classes is associated with weight loss , it's not sensitive enough to see the changes in body composition. more importantly, erica, it builds confidence in kids to actually have lifelong habits of physical activity . so we have to keep in mind what our end goal here is.

>> that's what's important, to instill that goal in kids. just to get moving every day so they carry it through their adult life.

>> absolutely. as you know, it's a lifelong struggle for many people trying to lose weight .

>> in terms of getting moving. there's talk about whether sex is a good workout. a good calorie burner. what is the verdict?

>> right. it turns out that sex doesn't burn a lot of calories. and this is really in line with a lot of recent research dispelling old myths that we need a lot of high-intensity, short bursts of activity. what we're seeing now is in order to lose weight , we need long, duration, high intensity. the average person, a sexual bout is six minutes. if this is your form of physical activity for six minutes, you have to increase the time you spend.

>> we'll have to leave it