Key Findings
This study found that consuming a high polyunsaturated fatty acids (PUFAs) diet may alter appetite hormones associated with hunger and satiety (3). The fatty acid profile was particularly high in alpha-linolenic acid (ALA). The clinical trial included 26 healthy, sedentary adults aged 18 to 35 years. Before the start of the intervention, the participants consumed a 3-day lead-in diet, representative of the average U.S. diet (providing 29%, 31% and 40% of energy at breakfast, lunch and dinner respectively). After the pre-diet, participants were divided into two groups and received either a PUFA rich diet (% energy from fatty acid – 21% PUFA including about 6.8% ALA, 5% saturated fatty acids [SFA] and 9% monounsaturated fatty acids [MUFA]) or a control diet (% energy from fatty acid – 7% PUFA, 13% SFA, 15% MUFA) for seven days. The control diet had the same macronutrient and fatty acid breakdown as the lead-in diet. PUFAs were provided by foods such as walnuts, salmon, tuna, flax seed oil, grapeseed oil and canola oil. The participants on the PUFA diet also consumed an additional 3g/d of combined eicosapentaenoic acid (EPA 2157 mg/day) and docosahexaenoic acid (DHA 843 mg/day). After a 7 day period, fasting concentrations of ghrelin, PYY, insulin and leptin from pre- to post-diet intervention were assessed. The results showed that the PUFA rich diet led to a significant decrease in fasting ghrelin concentrations (a decrease in the range of 200 pg/ml compared to the pre PUFA rich diet) and a significant increase in fasting PYY concentrations (increase in the range of 30 pg/ml). There were no changes in fasting insulin or leptin (a satiety hormone release by adipose tissue), and no change in any fasting hormones for the control diet. The postprandial response to the high fat meals showed a significant greater PYY response after the 7 day PUFA-rich diet. A subjective visual analogue scale (VAS) was used to measure hunger and fullness. No changes in VAS were found. The results showed that consuming a PUFA-rich diet favourably alters some hunger and satiety hormone responses but does not significantly alter subjective rating of hunger or fullness. Combined with participants’ feedback, the researchers concluded higher PUFA levels were more likely to leave consumers feeling full.
ABSTRACT
OBJECTIVE: Determine subjective and physiological appetite responses and ad libitum intake to high-fat (HF) meals rich in either monounsaturated (MUFAs), polyunsaturated (PUFAs), or saturated fatty acids (SFAs) in women with obesity. METHODS: In this single-blind crossover study, three HF meals (70% of energy) rich in MUFAs, PUFAs, or SFAs in 16 women with obesity were tested. At each visit, anthropometrics and a fasting blood sample were collected. Participants then consumed one of the HF meals, and postprandial blood draws and visual analog scale (VAS) measures were collected over 5 h. An ad libitum buffet lunch was provided 5 h after the HF meal. RESULTS: Decrease in ghrelin was significantly greater for PUFA (P < 0.05) and MUFA (P < 0.01) vs. SFA while the increase in peptide YY was significantly greater for PUFA vs. both SFA and MUFA (P < 0.05). Change in glucagon-like peptide-1, VAS measurements, or total energy consumed at the buffet showed no differences between HF meals (ns). CONCLUSIONS: Fatty acid composition differentially affected physiological markers of hunger and satiety. However, it was unable to show changes in subjective appetite ratings or changes in energy intake when alterations were made to fatty acid composition from an acute HF meal.
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