Taxation of the fat content of foods for reducing their consumption and preventing obesity or other ealth outcomes
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The issue: Overweight and obesity are increasing worldwide and are considered to be a major public health issue of the 21st century. Introducing taxation of the fat content in foods is considered a potentially powerful policy tool to reduce consumption of foods high in fat or saturated fat, or both.
What did the authors do? They searched for studies up to September 2019 that looked at the effects of a tax on the fat content of foods. They were interested in how a tax affected the: total amount of fat, and saturated fats eaten; total calories eaten; calories eaten from all fats and saturated fats; and rates of overweight and obesity.
What studies did they find? Authors found only two studies from Denmark, conducted during 2011 to 2012. One looked at how a tax on some high-fat foods affected household demand for them; the other looked at information on supermarket sales for certain high-fat foods (minced beef, cream, and sour cream). They compared their results with data from before the tax started.
Both studies looked at a small number of foods that people bought, but not what foods people ate. They didn't measure how much total fat or saturated fat were eaten.
What are the results of the review? If the amount of foods bought reflected the amount of foods eaten, then taxing the fat content of certain foods:
· might reduce the total amount of fats eaten by 41.8 grams a week for each person in a household, in one study of 2000 households; and
· might reduce the amount of saturated fats eaten (in minced beef and cream), in one study of 1293 supermarkets.
No studies measured the effect of taxing the fat content of foods on calories eaten, on obesity or overweight, or on total food sales.
How reliable are these results? The authors are not confident in the results because the evidence is only from two studies; and these studies only measured a small number of foods bought, and did not measure foods eaten.
The results were from observational studies, in which researchers observe the effect of a factor (such as taxation) without trying to change who does, or does not, experience it. Observational studies do not give as reliable evidence as randomized controlled studies, in which the treatments people receive are decided at random.
What the authors said: The authors did not find enough reliable evidence to find out whether a tax on the fat content of foods resulted in people eating less fat, or less saturated fat. They did not find any evidence about how a tax on the fat content of foods affected obesity or overweight.
The results of this review will change when further evidence becomes available.
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