The amount of fat we eat is the most important factor controlling hunger
and appetite. This finding is linked to the observation that as countries
grow richer, the national consumption of fat eventually levels out at around
40 per cent of the nation鈥檚 total energy intake.
鈥楾here seems to be an inherent tendency for free-choice diets to stabilise
at around 40 per cent energy from fat, so long as economic development allows,鈥�
says Martin Wiseman, head of the Nutrition Unit in Britain鈥檚 Department
of Health. Speaking at a conference in Reading, Berkshire, on fat and the
diet, Wiseman presented data from seven countries that supported the view
that as nations become richer, fat consumption edges up towards the 40 per
cent mark.
Japan, for example, where fat intake has traditionally been very low,
is now speeding towards the plateau. A survey of 20 000 Japanese published
this month by the country鈥檚 Health and Welfare Ministry, showed that fat
forms 25.7 per cent of the diet. In 1955 this figure was only 8.7 per cent.
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Wiseman speculates that the so-called 鈥榝at factor鈥� governing appetite
may have given humans some kind of evolutionary advantage in the past. People
with the most stored fat would be more likely to survive food shortages
than their leaner cousins. But, says Wiseman, such an adaptation may be
less healthy in today鈥檚 times of abundant food.
The new evidence supporting the 鈥榝at factor鈥� theory comes from John
Blundell, a reader in biological psychology at the University of Leeds.
He carried out a study in which he monitored the diet of two dozen active
young men. As part of their diet, the men ate special breakfasts which included
scones that were high, medium or low in fat.
Blundell concealed the amounts of fat in the three kinds of breakfast
by substituting to differing degrees real fat with Olestra, a sucrose polyester
that mimics fat but is not digested and contains no calories.
He found that subjects on the low-fat diets developed hunger pangs sooner
than those eating fat-rich diets, and they eventually began to make up their
calories by eating more carbohydrate, particularly in their evening meals.
He concludes that the calories in fat do help to satiate and suppress
appetite, but that the effect is not immediate, 鈥榮uggesting a post-absorptive
action鈥�. In other words, eating fat does not immediately satisfy hunger,
but it will restrain your calorie intake in later meals.
Wiseman said that whether the fat factor theory proves correct or not,
Britons still eat far too much fat. Only one-third of Britons have been
able to limit their energy intake from fat to 35 per cent, as recommended
by the Department of Health鈥檚 Committee on Medical Aspects of Food Policy
(see 鈥楤ritain鈥檚 deadly diet鈥�, New 女生小视频, 11 May).
