Kategori: Underreporting

Obviously! Obesity is a remarkably simple problem to solve. Eat less and move more. When energy expenditure exceeds energy intake, you lose weight. Many people claim to have tried eating less and exercising more and claim that it does not work. As this would be a violation of the laws of thermodynamics it is quite unlikely.

Not only do overweight people claim to break the fundamental laws of nature they also constantly lie about how much they actually eat.

Elaine Prewitt and coworkers examined the effect of a 37%-fat (HF) diet for 4 weeks followed by a 20%-fat diet (LF) for 20 weeks on body composition and weight in 18 premenopausal women with body mass index (BMI) of 18-44. They found that

Despite adjustments in energy intake to maintain weight throughout the study, by the end of the LF period, energy intake had increased significantly in comparison with the HF diet (119% of the HF intake, P < 0.0001). 

The authors knew what kind of people they were dealing with and wrote

We have no means of assessing the degree of food waste by subjects when meals were taken out but there was no reason to attribute the magnitude of energy increase we observed to overreporting of dietary infractions. By contrast, one would expect the subjects, particularly obese subjects, to underreport extra foods eaten.

W. Daniel Schmidt and coworkers exercised overweight women. All study groups were put on an energy restricted diet. The control group only dieted without changing exercise routines, but somehow they didn’t lose any weight. The authors write:

The fact that the control subjects in our study did not lose weight is perplexing and conflicts with other research that generally supports weight loss with caloric restriction [17, 18]. One explanation may be that subjects simply underreported the amount of calories consumed, thus making this an issue of noncompliance. 

Not only are fat people liars, but fat people on low fat diets are the worst. James Krieger, everyone’s favorite researcher, suggests that:

…subjects on low-fat diets systematically underreport energy intake compared with subjects on low carbohydrate diets.

In support of his theory he cites a study where weight loss from a low fat diet did not turn out as predicted.

Fat people on low fat diets are not only the worst liars around, they are also not very smart. Kelly A. Meckling and coworkers compared a low fat diet to a low carbohydrate diet in overweight men and women. They write:

Energy restriction alone predicted a weight loss of 5.5. and 6.9 kg, respectively, in the LF and LC groups, which was close to the observed values of 6.8 and 7 kg for the same groups. Slight differences, particularly for LF subjects might be explained by underreporting of habitual diets, as the subjects became better able to estimate their intakes and keep better food records as the trial proceeded. 

Those put i a low carb group obviously nailed the food reporting task right away, even before they actually were put on the diet, and missed the predicted weight loss by a mere 100 grams.

Everyone knows low fat fatties are the worst. Thermodynamics applied to food and the body is very simple, yet predicted weight loss are often not achieved by low fat fatties.

Writes Jennifer B Keogh and colleagues (when a low carb group lost more weight than a low fat group in their study):

Greater weight loss with a low-carbohydrate diet than with a conventional low-fat diet has been reported previously (2– 4, 57). Subjects in these studies reported similar energy intakes despite differences in weight loss, which suggests that the conventional diet group underreported their intake (3, 4, 57).

A group of Dutch researchers set out to test the extent of underreporting in 30 obese men. Their conclusion:

Total underreporting by the obese men was explained by underrecording and undereating. The obese men selectively underreported fat intake.

Not only did these men lie about how much they were eating, they didn’t even eat as much as they should have. They underrate. Those bastards!

If by chance you are wondering if the methods of the Dutch researchers were bulletproof, they weren’t. Still…

It is possible that overweight people under report more than lean people. But people seem to think that the under reporting somehow is the reason they are fat. They don’t know how much they eat and so they stuff themselves and grow fat. It is also possible that low fat diets does not work very well and that the human body is more metabolically complex than the simple energy calculations used predict.

But if overweight people do really under report more than «normal» weight people, are they then fat because they under report and lie, or are they perhaps under reporting because they are fat and afraid of being stigmatized as gluttonous and desperately trying to keep some of their dignity?