This review focuses on the possible association between types of
fatty acids and weight change. It examines the
biological plausibility underlining these associations and the evidence obtained to date from clinical trials and epidemiological studies. Animal studies have shown that dietary short- and medium-chain
fatty acids compared to long-chain
fatty acids appear to promote
weight loss. Similarly,
monounsaturated fatty acids (MUFAs) appear to favor
weight loss compared to
saturated fatty acids (SFAs) in human studies. The structure of
fatty acids seems to affect their degree of oxidation and deposition. Although results are conflicting, human studies follow the general trend reported in animal studies. These trials suggest that some
fatty acids are prone to oxidation and some others lead to fat storage when comparing isocaloric diets. For instance, n-3
polyunsaturated fatty acids (PUFAs), eicosapentaenoic and
docosahexaenoic acids are preferentially oxidizied to other PUFA but results remain inconsistent. Epidemiological studies concerning this issue reported that total
dietary fat, which includes MUFA, PUFA, and SFA could increase the risk of
obesity, but results are few and conflicting. The rising
biological plausibility linking
dietary fat quality and risk of
obesity, together with the rather recent addition of
fatty acids content in food composition tables, support the need for major epidemiological studies in that area.