Calories: does everybody lie?
This is the credo of House, the central character played by Hugh Laurie in the award winning television series. It’s a phrase Dr Gregory House constantly uses in the show. Now a UK study into calorie consumption as reported by the British public suggests he might be onto something.
The report, Counting Calories, How under-reporting can explain the apparent fall in calorie intake, published earlier this week by The Behavioural Insights Team suggests Britons are serially under-reporting their daily calorie consumption, pointing out scientific and economic data showing people eat 3,000 calories, compared to the 2,000 cited in official surveys. This is important as official figures are potentially misleading policymakers attempting to curb obesity, while of course it could also help explain rising obesity levels, despite decades of official surveys saying people are eating less. A link to the full report can be found at the conclusion of this article.
Where was Moses when the lights went out?
Like Moses, it seems UK government statisticians have been in the dark for a very long time about the true levels of calories shifted by their fellow citizens on a daily basis. Several official surveys, including the National Diet and Nutrition Survey and the Living Costs and Food Survey, suggest the amount of food people eat and buy has gone down in recent decades – while obesity rates continue to rise. This suggests that at the very least they need to get out more, as a mere glance at any High Street in the UK will bear witness to the burgeoning numbers of the overweight and obese.
But hunched over their computer screens, they may have concluded that the decline in levels of physical activity was the main cause of the growth of obesity, an important point in discussing and determining a national policy response. This report fortunately sets the record straight.
Why are the official government statistics not plausible?
Two main reasons are cited for why national surveys under-estimate true calorie intakes:
- The reported level of calorie consumption is too low to sustain our current weight, even with minimal activity. As a nation we would be losing weight, not gaining it.
- The studies using Doubly Labelled Water, the gold standard for measuring energy expenditure, indicate that as a population we are consuming 30-50% more calories than the levels reported in official statistics.
It’s also noted that data from a commercial source – the Kantar Worldpanel – indicates a rise in calorie purchases over the past ten years.
Further, reductions in physical activity do not provide a realistic explanation for the change in weight, while calorie intake appears to have fallen because under-reporting has increased over time.
Five main reasons are put forward why under-reporting may have increased:
- increasing levels of obesity (since obese people are more likely to under-report their intake)
- increased desire to lose weight (since this is associated with increased under-reporting)
- increased snacking and eating outside of the home
- falling survey response rates
- growing discrepancy between reference data (used to calculate calories) and true portion sizes or food energy density
Together, these factors point towards a serious increase in under-reporting. For my own part, I suspect the final point will have been one of the most important in the growth of under-reporting increasing over time, as the gap in quality of energy-dense, nutrient-poor processed foods versus real food reference data will have grown wider as increasing amounts of sugar, salt and trans-fats have crept into the processed food ingredients along with other potentially noxious additives. Time and again my experience is people completely underestimate the calories contained in even small portions of ready meals or takeaways in comparison to Real Food.
The good news is government statisticians have responded positively, with it reported that the way calorie data is collated will change. In the context of the government’s childhood obesity strategy, ensuring we have accurate measures of calorie intake is especially important, so this is a big step in the right direction. But perhaps the most important conclusion is that although attempts to increase physical activity should be part of the policy mix for obesity, they should not act as a distraction from the central importance of reducing calorie consumption.
I would go a step further: increased education about the nature of food and the importance of what we actually consume should be the priority. We have passed the point of simple calorie reduction being sufficient to fight the obesity crisis. Examining what we actually eat is much more important than a policy simply targeting levels of calories consumed or energy burned. Real Food and improved tracking of nutrition must be the focus to providing a genuine solution.
Just as in every episode of House, the truth came out in the end – hopefully it will ultimately help set us free from the obesity trap. However, I’m inclined to give the public the benefit of the doubt when it comes to questioning their honesty. Ignorance about the calorific value of processed foods and takeaways, plus growing portion sizes, are more likely the cause of underestimation than wilful blindness or lies. But is this not even more scary, pointing to an even bigger educational challenge around food and obesity than already envisioned?
The Behavioural Insights Team
Counting Calories – How under-reporting can explain the apparent fall in calorie intake
Hugo Harper and Michael Hallsworth
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