A report in the New England Journal of Medicine is getting a lot of press mainly because of it's refutal of a purported myth about sex and calorie burning. Sex works good for headlines and attention grabbing.
I'll bust the so called myth busting. The report is partially almost accurate in a sort-of-maybe way.
I don't know what the intention of the report was, but most of the conclusions it draws are contrived and not evidence based. Which is a rather pathetic irony since the study authors are fairly boisterous about presenting their report as being a myth buster pointing out common myths about weight loss and weight gain.
The report identifies "7 obesity-related myths":
Small changes in exercise or food consumption will add up over time resulting in weight loss.
They challenge the idea that if someone burns 100 calories in a day that over 35 days they will lose a pound of fat, apparently debunking the "myth" that 3500 calories equates to a pound of fat.
It is true that, in isolation, if someone were to eat 100 calories less or burn off 100 calories more every day that no actual weight change may occur. A person might even gain weight.
Here's how the reports take on this is sneaky..
The reality is a significant caloric deficit is required to lose fat. Nothing else can cause fat loss.
Will eating 100 calories per day less do this? Not if a person is overeating by 300 calories per day and they cut back by 100. They'd still be overeating by 200 calories per day.
Pretty sneaky. Because this is true, these researchers can make the claim that a small reduction in calories added up over time wont cause weight loss.
They also make the point that if you do reduce calories in - out so you do have a long period of caloric deficit and you do lose weight, the rate of weight loss will eventually level out because when you weigh less your caloric needs are less so what was a calorie deficit when you were heavier is no longer a calorie deficit at a lighter weight.
Therefore, these researchers say, it is a myth that sustained caloric deficits cause sustained weight loss.
You know that feeling when someone says something that is a flat out lie, but at the moment you can't say anything about it, and you feel that stressed, anxious feeling in your gut? You want to expose the liar, but you can't?
Thats what I feel when I'm typing out what these researchers reasoning is. I hate that feeling. Fortunately I can say something about this flat out, and utterly bizarre lie.
First, a person who is losing weight consuming fewer calories than expended is obviously successfully losing weight. There is no myth here.
Second, if by the time what amounted to a deficit now becomes equal calories in - out the person still needs to lose weight, the obvious course of action is to eat less or exercise more to create a caloric deficit again.
For example, if a person weighed 250 lb. and with their daily activity needed 2500 calories per day to maintain their weight, eating 2000 to 2300 calories per day would provide a reasonable caloric deficit and they would lose weight.
Once they lost around 20 lb. though, they would have less mass to push around for the day so their calories needed to maintain weight would no longer be the same as when they weighed 250 lb.
The 2000 - 2300 calories per day would need to be adjusted to account for the weight loss, if more weight loss was needed. 1800 calories per day might be the new daily intake they need.
Here's the reality check that this report failed bring to readers attention:
It's already known that a persons mass, how much they weigh, is a primary variable in figuring out how much food energy they need to consume. Obviously if someone weighs less the daily needs value for a previous heavier weight would no longer apply. We know this. There is no myth here.
The only grain of truth is that it is unrealistic to expect dropping 20 calories from your daily intake is going to add up to any significant weight loss. Don't be thinking that not putting a spoonful of sugar in your coffee is going to translate into real weight loss over time.. it wont. The amount is too small. The normal variability of how much we eat and move in a day is far greater than 20 calories, so we can't add up small calorie changes over time.
Myth about myth, busted.
Establishment of realistic weight goals
Apparently because they found two studies where some people lost weight with aggressive weight loss goals, that somehow nullifies all those who have successfully lost weight with smaller more achievable goals.
The reality is that for most people, small, moderately challenging goals over longer periods result in greater long term success than trying rapid weight loss.
For the majority of people smaller goals, like losing 5 - 6 pounds every month or two provides a better result that trying for 2 pounds every week.
It's great that some can have success with a more aggressive approach and if someone has the personality type that can do this, that's great, but more people lose weight successfully more slowly over longer periods.
Myth of myth, busted.
Weight loss readiness
If people have been thinking about weight loss for a long time but never acted on it, but then reached a state where they felt motivated to act on losing weight, their "readiness" does not guarantee success in weight loss.
No, it isn't a guarantee of success, it's a guarantee of a start.
This one is so twisted. It doesn't even make sense. I really have to wonder what is on these researchers minds to even say what they said about this. It's non sequitur.
There is no claim that state of readiness guarantees weight loss success, so it can't be claimed that this is a myth.
If a person feels ready to start losing weight on their own or to seek help in doing so, they should.
Phys-ed classes in school wont cause weight loss.. they're too short and the intensity is too low
This doesn't sound like myth busting. This sounds like pointing out a problem with not exercising enough. Also, it doesn't matter how much kids exercise in phys-ed class, if any person, child or adult, eats more than they burn off, weight loss will not occur. So if 400 calories is burned off in Phys - ed but a 1000 fast food lunch is consumed making for a calorie surplus for the day, the Phys - ed class wont have an obesity preventative affect. But this doesn't mean Phys -ed can't be part of the solution.
This one is almost agreeable. We shouldn't believe that a gym class will resolve childhood obesity.
A more complete approach of teaching the values of healthy living choices including eating less and getting the right amount of exercise is the right idea.
It isn't really a myth that phys - ed can't work though.
Breast feeing prevents obesity
Ok, this is a myth. Breastfeeding alone is too small a variable over a child's development to be a singular preventer of obesity.
Sex burns lots of calories
It depends. The researchers cited old studies that measured intimacy lasting about six minutes. If that's your metric then, no, sex will not be a big calorie burner.
Even if the deed is done for longer periods, on average the total calories burned during sex is not very high.
So this one is true, sex, on average, does not burn off a lot of calories, but, I'm sure there are some exceptions..