Summary of findings 1. Taxation of the fat content of foods compared to no taxation for reducing their consumption and preventing obesity or other adverse health outcomes.

Taxation of the fat content of foods compared to no taxation for reducing their consumption and preventing obesity or other adverse health outcomes
Patient or population: general population of Denmark Setting: Denmark Intervention: taxation of the fat content of foods Comparison: no taxation
Outcomes	№ of participants (studies) Follow up	Certainty of the evidence (GRADE)	Impact
Total fat consumption	2000 households (ITS design) (1 observational study)	⊕⊝⊝⊝ VERY LOW 1 2	There is very uncertain evidence that taxing the fat content of foods reduces estimated total fat consumption by 41.8 grams per week, per person in a household (P < 0.001).
Total saturated fat consumption	1293 supermarkets (ITS design) (1 observational study)	⊕⊝⊝⊝ VERY LOW 1 2 3	There is very uncertain evidence that taxing the fat content of foods reduces the estimated saturated fat content of sales by 4.2% for minced beef and by 5.8% for cream, and increases the estimated saturated fat content of sales by 0.5% for sour cream. (No measure of statistical precision was reported for any of these results.)
Energy intake	See comment	0 (0)	Not reported4
Overweight	See comment	0 (0)	Not reported4
Obesity	See comment	0 (0)	Not reported4
Total sales	See comment	0 (0)	Not reported4
ITS: interrupted time series
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

¹ Observational studies with an ITS design start out at the level 'low‐certainty'.
² Downgraded 2 levels because of indirectness (calculation of effect estimates were based on a restricted number of food items and sales/purchases of food items was used as a proxy to measure consumption).
³ Downgraded 2 levels because of imprecision (study did not report confidence intervals, P values or any other measure about the statistical precision of the effect estimates).
⁴ No study measured the effects of taxing fat content of food on energy intake, overweight, obesity, or total sales.