First published by Spectator Health in August 2016
Three years ago, a study found that people in Britain drink considerably more than they say they do. It became an international news story even though it is common knowledge among researchers that drinkers greatly under-report their intake.
This week a report
found that people in Britain eat considerably more than they say they
do. This, too, has received an enormous amount of news coverage despite
the fact that anybody who has spent more than five minutes with the data
knows that under-reporting is endemic in this area too.
In the case of alcohol, we don’t need surveys to tell us how much
we’re drinking because we’ve got the tax receipts. All we have to do is
estimate how much has been spilled or abandoned and we can work out
average intake with relative ease.
Food is more difficult. We have surveys showing what people say they
eat and we have surveys showing what people say they bought, but people
cannot be trusted to recall what they have eaten and a lot of food is
thrown away. If we took the Living Costs and Food Survey at face value,
the average Briton eats only 2,192 calories a day. This is implausible
when 25 per cent of us are obese. (The government recommends men and
women eat 2,500 and 2,000 calories a day respectively).
All sources are agreed on one point, however: we are eating fewer
calories as a fat nation than we did as a slim nation. World War Two
rations were designed to give civilians 3,000 calories a day. In the
late 1940s, scientists found
that people lost weight if they got less than 2,900 calories a day. A
survival diet 70 years ago would be an obesogenic diet today.
It is safe to assume that calorie consumption rose when rationing
ended, although statistics are thin on the ground until the Living Costs
and Food Survey started up in 1974. In its first year, this survey
reported that 2,534 calories per day were consumed in the home (it did
not look at eating out). By 2012, with eating out now included, this had
fallen to 2,192 calories.
The exact numbers found in these surveys are misleading due to under-reporting, but the trend is clear. The Institute for Fiscal Studies has written about these data before, as have I for the Institute of Economic Affairs.
Not everybody is convinced, however. The Behavioural Insights Team —
commonly known as the Nudge Unit and now privatised — yesterday released
a report claiming that ‘calorie consumption has not significantly decreased over time’.
Their argument is that under-reporting is endemic and has got worse
in recent decades. They suggest several reasons why people today might
be more inclined to forget or lie about what they have eaten, such as
the tendency of obese people to under-report more than slim people and
the general awareness of obesity as a health issue. These are worthwhile
considerations and I agree that they have played a part, but
researchers are well aware of them (they are mentioned in both the IFS
and IEA reports). In my view, it is very unlikely that they can explain
all of the self-reported decline in calorie consumption, let alone that
they have masked a rise in calorie consumption. The self-reported
decline is just too steep.
With the exception of the mavericks at Public Health Collaboration,
nobody seriously believes people are consuming 400 fewer calories than
they did in 1974. The question is whether we are eating more calories
than they did back then. The Nudge report accepts that we are not.
Instead it says that, after correcting for under-reporting, ‘the decline
since 1974 is a lot smaller than previously stated — around 200kcal per
day compared to around 400kcal’.
This is an important finding because it confirms people are eating less today than we did forty years ago. Given that obesity rates were very
low in the 1970s, it leads to the obvious conclusion that a decline in
physical activity, not an increase in food intake, has driven the rise
in obesity. But this is the opposite of the Nudge Unit’s thesis and so
they spend several pages trying to debunk the notion that people are
less physically active than they used to be.
This is the weakest part of the report because they resort to a tactic used by our old friend Aseem Malhotra
and use leisure time exercise as a proxy for physical activity. Surveys
show an increase in the number of people who follow the Chief Medical
Officer’s recommendation of exercising for 30 minutes five times a week.
The data-set only goes back to 1997 and the Nudgers acknowledge that it
contains the same kind of self-reported figures that they have just
criticised, but that is only part of the problem. There is no
contradiction between a third of the population taking part in regular
leisure time exercise and a quarter of the population being obese. They
are not the same people.
Moreover, people only exercise in their spare time when they are not
getting enough physical activity in their daily lives. People did not
need to go to the gym 70 years ago because they had naturally active
lifestyles. Sure enough, there are figures tucked away in the appendix
of the Behavioural Insights Team’s report showing that men expend 100
fewer calories at work today than they did in the early 1980s. Combine
that with the rise in car ownership, the decline of walking and the rise
of labour-saving devices and it is easy to see why physical activity
has declined by 24 per cent since the 1960s, as Public Health England says it has.
Despite torturing the data, the Nudge Unit team fails to extract a
confession. After throwing everything they can at the statistics, the
best they can manage is the claim that calorie consumption has not
fallen as much in the last 40 years as a naive interpretation of food
surveys might suggest. But we are already knew that, just as we know
that people drink a lot more than they say they do. The fact remains
that calorie consumption has fallen over the long term and so has
physical activity. If, as the Nudge Unit admits, we are eating fewer
calories than we did in the 1970s, a decline in physical activity is the
only possible culprit.
The authors of the report seem to believe that there are competing
views on how to tackle obesity with one side claiming that it is futile
to reduce calorie consumption because it has failed to reduce obesity in
the recent past. I’m not sure that is true. It is certainly not my
position. Reducing calorie consumption is as valid an approach as
increasing physical activity. Indeed, reducing calorie consumption might
be a more realistic option for many people. Whether the government has
the ability or mandate to reduce calorie consumption is another issue,
but regardless of where you stand on that question we should not rewrite
history. The notion that obesity started rising after 1980 because the
nation was consuming more and more calories remains a myth.
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