An unfortunate fact is that no conversation around food tracking, which is really a form of self-reporting one’s food intake, can be held without addressing the elephant in the room – people are often very poor at reporting their food intake, even when they think they aren’t.
There are two categories of people who misreport their food intake which can each be broken down into subcategories, and we will do our best to cover all of them here after first defining exactly what we are talking about.
Food misreporting is the simple act of putting false information on a food recall or on-going food diary, with the difference being that the former is completed at the end of a given period (so someone might track their food at the end of the day, week or longer by remembering what they had) and the latter is done by ‘tracking as you go’ throughout your day-to-day life.
Most people, when asked, do not believe that they do this but the fact is that almost everyone does.
In nutritional research there was a widely-held belief until recent years that obese people generally did not eat more calories than their lean counterparts, which represented an obvious problem – if people are eating the same amount, how can one of them weigh 50% less than the other? This has led to numerous explanations including uniquely fattening foods, food groups or macronutrients, hormonal problems, an oversimplified idea surrounding genetic factors and much more, but more recent research has unearthed the truth.
In research where overweight or obese people report that they eat a ‘normal’ diet and provide a food diary to prove it, they aren’t reporting the truth regarding what they eat. This can be demonstrated using various techniques including Doubly Labelled Water (DLW) and Indirect Calorimetry (IC). In DLW trials, subjects are given water in which the hydrogen and oxygen have been replaced by different isotopes, and then scientists can measure the clearance rate of these. The rate of clearance allows a researcher to ascertain an individual’s metabolic rate. In IC trials subjects breathe in a special hood which measures their oxygen consumption and ultimately performs more or less the same function.
Thanks to these two techniques it has been possible to ascertain that overweight and obese individuals use roughly as many calories per day as you would expect given their weight, height and activity level – this tells us that they must be eating more than they say they are. But it happens more than you would think even in individuals who are lean.
Looking across all the data, it seems that up to 70% of people misreport up to around 50% of the calories that they really consume, meaning someone eating 3600 calories could report a consumption of 1800. The foods which are typically missed off are those that you would expect, junk food, sweets, baked goods and snack foods, though it’s interesting to note that dietary fat and carbohydrate are both often underreported whereas protein is over reported (or rather foods these macronutrients are contained within are misreported).
This cannot be put down to lack of understanding of the reporting process as subjects in many studies are counselled on how to use the reporting method they are asked to use, and far more crucially it cannot always be put down to lying because subjects misreport even when they know that the researchers will be able to test and find out what the true value is.
Adding weight to the idea that a lot of misreporting is unintentional, is the fact that snack foods are misreported the most, and that those who eat irregular meals as opposed to routine meals at given times are more likely to provide false data. It’s not hard to see why – these are the foods and this is the dietary schedule which is most likely to lead to someone ‘forgetting’ what they have eaten, or simply not tracking their food immediately and unconsciously neglecting to be honest about them later when remembering what they have eaten that day.
So why do people misreport, and what can be done about it?