Links Between Dietary Fat & Obesity
Prevalence of Obesity
The prevalence of obesity is increasing worldwide, which indicates that
the primary cause of obesity lies in environmental and behavioral changes
rather than in genetic modifications. Among the environmental influences,
the percentage of fat energy of the everyday diet and the lack of physical
activity are two important factors, which contribute to explain the rising
prevalence of obesity. In this review, several lines of evidence are presented
to illustrate why dietary fat does affect obesity development. There are
four factors which support a link between dietary fat and obesity development:
High Fat Diet & Obesity
The thermic effect of nutrients, expressed as percentage of their energy
content, is 2-3 percent for lipids, 6-8 percent for carbohydrates and
25-30 percent for proteins. This means that the efficiency of nutrient
utilization (calculated as 100 percent, ¾ the thermic effect of
the nutrient) is higher for fat than for carbohydrate or protein. Postingestive
fuel selection favours the oxidation of dietary proteins and carbohydrates,
whereas dietary fats are preferentially stored as triacylglycerol in adipose
tissue. Alcohol, by inhibiting lipid oxidation, indirectly favours the
storage of dietary fats.
High-fat diet promotes excessive energy intake by passive over-consumption;
the fat-induced appetite control signals are too weak or too delayed to
prevent excessive energy intake from a fatty meal.
The only proof that dietary fats contribute to weight gain is to test
the long-term effect of ad libitum low-fat diets. Most studies on low-fat
diets show that they induce a modest weight loss in obese individuals,
but their long-term effect from a public health perspective is limited,
probably due to a low compliance to the dietary advice.
Source: International Journal of Obesity
(2002)
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