Discrepancies Between Self-reported and Accurate Caloric Intakes

“I’m eating 1200 calories and I still can’t lose weight.”

“Nothing works for me… I’ve tried everything.”

“Diets just don’t work for me.”

If you’re a coach or someone who has dieted before (successfully), you’ve most likely heard these statements more times than you can count. While some may wind up in these situations where they’re eating little and seeing little to no results (metabolic adaptations due to prolonged dieting efforts), a lot of people may simply be making errors on their end.

This is commonly in the form of underreporting or underestimating just how much one is eating day to day. Tracking to the ounce or gram is very different from estimating (or “guesstimating”) meals when you have no real tracking experience prior.

Alongside this, seeing the calorie counts/macros out in front of you gives you a much better idea of how things add up over the course of the day, rather than keeping ‘mental tabs’ on your meals and omitting little details like your morning coffee or the add-ons in your salad at lunch when you go and estimate later on.

Just how much of an impact can a few errors make? Well, it turns out that these discrepancies can be quite significant. Understandably, errors on this end this would make most of our other efforts and habit changes go to waste. This is especially so since the I’m-eating-less-and-don’t-see-results individuals may be more prone to throwing in the towel before getting to the bottom of the issue.

 

Failing to Lose Weight

There are two primary explanations for why some individuals aren’t seeing success: intaking more total calories than they think and overestimating how much physical activity they are doing. Yep, the opposite happens too! Overestimating energy expenditure is just as much a possibility here. Both of these factors work together to create a caloric deficit.

I’ll spare you from my speech on energy balance, but if you want to learn more make sure to check out our podcast!

Now to answer the question – to what extent does underreporting calorie intake and overestimations of energy expenditure account for the failure to lose weight in those who are supposedly eating 1200 calories or less per day?

 

Underestimating and Overestimating

It should be noted that this population consisted of obese individuals. This, in part, makes sense as participants in this study were screened for having histories of “diet resistance.” This resistance was defined as having a current intake of less than 1200 calories per day, weight stability for the past 6 months, and having a history of failing to lose weight despite following a hypocaloric diet, or in other words, being in a caloric deficit.

16 individuals met these criteria (10 of which completed the study) and made up the diet-resistant group. They each met with a dietitian for instruction on how to record and track their intakes and physical activity. The remaining subjects were used as a control group.

 

Accuracy Testing

Estimation errors are very common, especially for those who are not accustomed to tracking their daily intake and weighing food out. Tracking macros and recording everything you consume, even for a short amount of time, serve as important learning tools for this very reason – we get to see portion sizes in front of us alongside their nutrition information. It gives us a much better idea of how much we’re truly getting every day, this way we can move forward and make informed decisions about our meal choices.

Researchers decided to test the accuracy of the subjects’ portion size estimations. The subjects (the diet-resistant group as well as 10 from the control) were asked to first estimate the size of various standard food items.

To then test the subjects’ reports of their own food intake, a test meal was used under lab supervision. Each group was instructed to eat a given lunch (composed of a variety of foods) until about ~80% fullness. 24 hours later they were then called by an investigator and asked to report the meals they had eaten the day prior as well as the amounts eaten. The results of each subject’s test meal recall were then compared to the weight of the actual amount of food consumed while under standardized conditions.

 

Diet Discrepancies

Differences between the subjects’ estimated and actual intakes were quite large. Subjects in the diet-resistant group reported an average calorie intake within a range of 880-1,176 calories per day. However, their true intake was actually anywhere between 1,500 and 2,500 calories per day. This means that participants significantly underreported their calorie intake by an average of 1,053 calories (or a 31-63% difference). Another interesting finding was that the diet-resistant group wound up overreporting their total energy expenditure/activity level.

This didn’t only go for the diet-resistant group though. The control group also experienced similar discrepancies in their reported intakes and expenditure, albeit just not as significant as the diet-resistant group’s.

Estimates of portion sizes were determined to be accurate and comparable for both groups. Upon having the test meal while under standardized conditions, the diet-resistant group reported an intake about 20% lower than what they actually ate, whereas the control overestimated their intake by 12%.

 

Application

The primary finding of this study is that if you or someone you know is struggling to lose weight despite “doing everything right” and “eating healthy,” you may want to test your accuracy with tracking before deciding that nothing works. It’s a much more common explanation than you may think. The same can be said for cardio and physical activity.

Ultimately the goal here is to have these controllable variables (nutrition, training, cardio) in check before we go and adjust things. As a coach, I’ve seen this happen quite a few times where I need to check in on accuracy/tracking methods and activity in and out of the gym. This covers our bases.

Think about it. If I make changes to your diet/cardio when it’s already unreliable, inconsistent, or inaccurate, we’re making changes based off of false information. This just slows us down in the long run.

Tracking our intakes and keeping tabs on the physical activity we’re doing throughout the process is such an important learning tool. It’s easy to think these things are overwhelming or time-consuming, but a little bit of effort in these areas goes a long way in being able to apply that knowledge long term and make well-informed decisions moving forward, rather than being stuck spinning your wheels.

References:

Lichtman, S.W., Pisarska, K., Berman, E.R., et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. The New England Journal of Medicine. 1992. 327:27