Relationship of the Reported Intakes of Fat and Fatty Acids to Body Weight in US Adults.

Key Findings:

This study assessed associations between different fatty acids and obesity status among humans in observational studies.  The authors examined the extent to which reported intake of selected fatty acids, from 24-h dietary recalls, were associated with the prevalence of obesity. Fat intake was derived from reported food intake from NHANES diet recalls (2005–2012). Protein, total fat, total saturated fat (as well as long-chain saturated fatty acids 14:0–18:0), and MUFAs were positively associated with BMI. Lauric acid (a medium-chain saturated fatty acid, 12:0) and total PUFAs (as well as all individual PUFAs) were not associated with BMI. Non-Hispanic blacks showed positive associations between BMI and total PUFA (including LA and ALA). No relationship between long chain n-3 and BMI were noted as the intake of LCn-3 in this data is very low.  An increased β-oxidation of unsaturated lipids is related to reductions in body fat mass. These findings support those of experimental studies that demonstrate fatty acid-dependent associations between dietary fatty acid composition and body weight. Future changes in fatty acid intake, as a result of changing consumer food preferences or industry reformulation of fats and oils, may change the association of dietary fat and oil intake to BMI.

ABSTRACT

Dietary fat composition may modulate energy expenditure and body weight. Little is known about the relationship between fatty acid intake and body weight at a population level. The purposes of this study were to compare intakes of energy, macronutrients, and individual fatty acids across BMI categories (1) for the US adult population and, (2) by sociodemographic groups. Reported dietary intake data from the National Health and Nutrition Examination Survey (NHANES) and What We Eat in America (WWEIA) surveys in the years 2005-2012 were analyzed. Overall, we found that the reported intake of carbohydrate, protein, total fat, total saturated fat (as well as long-chain saturated fatty acids 14:0-18:0), and monounsaturated fatty acids (MUFAs) were positively associated with BMI; while lauric acid (a medium-chain saturated fatty acid, 12:0) and total polyunsaturated fatty acids (PUFAs) (as well as all individual PUFAs) were not associated with BMI. Non-Hispanic black individuals demonstrated a negative association between BMI and energy intake and a positive association between total PUFAs, linoleic acid (LA), α-linolenic acid (ALA) and BMI. Individuals with less than a high school education showed a negative association between BMI and DHA. Mexican-Americans reported intakes with no association between BMI and energy, any macronutrient, or individual fatty acids. These findings support those of experimental studies demonstrating fatty acid-dependent associations between dietary fatty acid composition and body weight. Notably, we observed divergent results for some sociodemographic groups which warrant further investigation.