Fat and fattening: exploding the myths

My Times column on low-fat diets and the evdience
behind them:

The diet police are on the prowl: if you hear a
knock on the door, hide the sugar bowl, the butter dish and the
salt. A draft report from the scientific advisory committee on
nutrition said last week that we should halve our intake of sugar.
The campaign group Action on Sugar wants “a total ban on advertising of
ultra-processed foods that are high in saturated fats, sugar and
salt, and sweetened soft drinks, to protect children”.

I have been curious about this new demonisation of sugar. I now
realise that it conceals a grudging admission that fat is not bad
for you after all, but the experts cannot bring themselves to say
so. There is a strong possibility that the “diabesity” epidemic has
been caused largely by the diet police themselves.

So argues a devastating new book: The Big Fat Surprise by Nina
Teicholz, an experienced journalist who spent eight years tracking
down all the evidence for and against the advice to eat low-fat
diets. She finds that it was based on flimsy evidence, supported by
an intolerant consensus backed by vested interests and amplified by
a docile press. And it made us fatter.

In the 1950s heart disease had come from nowhere to be a big
killer in America, especially of men in middle age. Although we now
know that cigarettes were a huge cause — and the sharp recent
decline of deaths from heart disease is mainly due to people
smoking less, plus better treatments — scientists quickly decided
that eating fat was the cause. Cholesterol clogs arteries, so
eating high-saturated-fat food such as meat, eggs and dairy
products must cause high cholesterol in the blood. Plus, eating fat
makes you fat. Obviously, no?

The chief source of the anti-saturated-fat message was a
politically astute scientist named Ancel Keys. In 1961 he persuaded
the American Heart Association to issue guidelines on saturated fat
intake. The main evidence came from his study of heart disease in
six countries in Europe plus Japan, from which he concluded that
low-fat diets led to less heart disease.

Yet the data in the study were awful, Teicholz says. Keys left
out countries that he knew produced inconvenient results, most of
his low-fat countries were ones still recovering from wartime
starvation, his dietary evidence came from a tiny subset of the men
in his clinical sample, and his lowest-fat diet was from Crete
during Lent, when meat-eating all but ceased. He published results
in obscure German journals. Teicholz told me these were huge
methodological problems, which should have called the entire study
into question.

Even so, the fat effect was weak: an order of magnitude less
than the effect of cigarettes on cancer, for example. Yet it was on
this feeble and dodgy dossier that an entire edifice of advice was
built. Sceptics kept pointing out inconvenient facts, but were
ignored. How come native Americans, Inuit and Masai ate mostly meat
and fat but had almost no heart disease or obesity, while they
immediately got both when they started eating bread and potatoes?
How come controlled trials of veterans and prisoners found that
substituting vegetable oils for animal fats caused no change of
overall mortality rates?

Anyway, we now know it just is not true that eating fat is what
makes you fat. The body does not shunt butter directly to your
thighs; it processes all food and adds to or draws down from fat
reserves based on hormonal signals. Fat has more calories per unit
of weight, but it’s also more satiating. All the best evidence now
suggests that it’s easier to gain weight on a high-carb than a
high-fat diet because the latter is more filling.

The sceptics were silenced by Keys and his allies and howled
down by obedient journalists, a profession in love with
conventional wisdom. Teicholz documents how the fat folk reviewed
each other’s papers, funded each other’s projects and kept the
doubters out, so that they gradually left the field. (Reminiscent
of modern debates on climate change?)

The American Heart Association, built up into a major force with
funding from the vegetable-oil industry, relentlessly pushed the
message that animal fat was bad. The US government issued
guidelines in 1978. We in Europe followed suit, as we tend to do.
And the message was driven home in the culture. Low-fat became a
craze. It still is: look at supermarket shelves.

In the past ten years, study after rigorous study has found that
animal fat per se is not harmful, does not cause obesity, does not
raise the kinds of cholesterol that predict heart attacks, does not
increase death rate and is healthier than carbohydrates. For
instance, one two-year trial in Israel found that a fat-and-meat
“Atkins” diet lowered weight more than either a low-fat or a
Mediterranean diet. As Teicholz puts it in her book: “Every plank
in the case against saturated fat has, upon rigorous examination,
crumbled away.”

Such findings remain too heretical for most diet experts. Those
who make them struggle for years to get published and have to couch
their findings in cautious language. Those such as Teicholz and
Gary Taubes who write books pointing out that this fat emperor had
no clothes are treated as pariahs. If anything, the official
committees of the diet police are doubling down, demanding that we
eat ever less saturated fat.

However, they are also now shifting the emphasis of their
disapproval to sugar. In fact, while the evidence against
carbohydrates in general as the cause of obesity and diabetes is
good, the evidence against refined sugar being peculiarly evil is
not. And there’s a real problem developing. If we are to condemn
carbs and sugar (and therefore fruit), and still condemn fat and
red meat (as Action on Sugar does), then there’s not much left to
eat except sea bass and spinach. Which is not practical.

The message is all stick and no carrot, which is no way to win
people round. So here’s a suggestion for the diet police: put out a
poster saying “We now think you should eat less sugar and bread,
but that you should feel free to eat more eggs, meat and cheese
again (but we might be wrong)”.

The subtitle of Teicholz’s book is: “Why butter, meat and cheese
belong in a healthy diet.” Yesterday I cooked bacon and eggs for my
breakfast. And by the way, I don’t have a vested interest: my farm
has a dairy herd, but then it also grows wheat and vegetable
oil.