Summary
This pilot study examined whether oleic acid (OA), the primary fat in olive oil, and linoleic acid (LA), the main fat in seed oils, have different effects on appetite and metabolic hormones in overweight and obese individuals. Eight participants consumed three test meals on separate occasions—a high-carbohydrate control meal, a high-OA meal, and a high-LA meal—each providing 30% of daily energy intake. Appetite ratings and metabolic hormones were measured for just over three hours after each meal.
While all meals initially increased fullness, differences emerged in appetite regulation and hormonal responses. The control and high-OA meals reduced participants’ anticipated food intake, indicating better satiety, whereas the high-LA meal did not. Notably, the high-LA meal significantly increased ghrelin, the hormone that stimulates hunger, suggesting a quicker return of appetite. It also caused an acute rise in resistin, a hormone associated with impaired insulin signaling and metabolic dysfunction.
Overall, the findings suggest that linoleic acid may promote hunger and adverse metabolic signaling compared with oleic acid, which appeared more neutral or favorable for appetite control. Although preliminary and based on a small sample, the study supports the idea that the type of dietary fat—not just total fat intake—can influence appetite regulation and metabolic health.
PMID: 30261617
DOI: 10.3390/nu10101376
Abstract
Despite the abundance of plant-derived fats in our diet, their effects on appetite, and metabolic markers, remain unclear. This single-blinded 3-way cross-over pilot study aimed to investigate the ability of the two most abundant dietary plant-derived fats, oleic (OA) and linoleic (LA) acids, to modulate postprandial appetite and levels of circulating appetite and metabolic regulators in overweight/obese individuals. Meals were a high-carbohydrate control, a high-OA or a high-LA meal, and provided 30% of participants’ estimated energy requirements. Meals were consumed after an overnight fast, with blood samples collected over 3¼ h. Appetite parameters were assessed via a validated visual analogue scale questionnaire. Hormones and other circulating factors were quantified using multiplex immunoassays. Eight participants (age 45.8 ± 3.6 (years), body mass index 32.0 ± 1.3 (kg/m2)) completed the study. All meals significantly increased fullness and reduced desire to eat. The control and high-OA meals significantly decreased prospective food intake. The high-LA meal increased ghrelin levels (p < 0.05), a hormone which encourages food intake. This was coupled with a significant acute increase in resistin levels, which impairs insulin signaling. Taken together, this study indicates that in overweight/obese individuals, high-LA meals may promote excess energy intake and alter glucose handling, though a larger cohort may be required to strengthen results.
Naughton SS, Hanson ED, Mathai ML, McAinch AJ. The Acute Effect of Oleic- or Linoleic Acid-Containing Meals on Appetite and Metabolic Markers; A Pilot Study in Overweight or Obese Individuals. Nutrients. 2018 Sep 26;10(10):1376. doi: 10.3390/nu10101376. PMID: 30261617; PMCID: PMC6213143.