A randomized 3x3 crossover study to evaluate the effect of Hass avocado intake on post-ingestive satiety, glucose and insulin levels, and subsequent energy intake in overweight adults

BACKGROUND: The behavioral outcome of food ingestion is a complex process that involves psychological and biological factors. Avocados are nutrient dense with properties that may favorably impact energy balance. This study sought to evaluate if incorporating approximately one half of a Hass avocado by addition or inclusion into a lunch meal will influence post-ingestive satiety, glucose and insulin response, and subsequent energy intake among overweight adults. METHODS: This was a randomized 3x3 single-blind crossover design study with 26 healthy overweight adults (mean ±SD age 40.8±11.0 years and BMI 28.1±2.4 kg/m(2)). Participants consumed a standardized breakfast followed by 1 of 3 lunch test meals [Control (C), avocado-free; Avocado Inclusive (AI); and, Avocado Added (AA)]. Participants rated five appetite sensations using a visual analog scale (VAS) before lunch and at specific intervals over 5 hours following the start of the test meal. Blood glucose and insulin were measured before lunch and at specific intervals over 3 hours following the start of the test meal. Mixed models were used to compare differences among the 3 test meals, and the area under the curve (AUC(0-xh)) was computed for the VAS and biological measures. RESULTS: There were significant differences in the AUC((0-5h)) for the self-reported feelings of satisfaction (P=0.04) and desire to eat (P=0.05) in the mixed model analysis. Compared to the C test meal, the AA test meal increased satisfaction by 23% (P=0.05) and decreased the desire to eat by 28% (P=0.04) for the AUC((0-5h)). For the AUC((0-3h)), the AA test meal increased satisfaction by 26% (P=0.02) and decreased the desire to eat by 40% (P=0.01) as compared to the C test meal. Compared to the AI meal, the AUC((0-3h)) for blood insulin was higher in the C and AA meals (P=0.04 and P=0.05, respectively). CONCLUSIONS: The addition of approximately one half of a Hass avocado at a lunch meal can influence post-ingestive satiety over a subsequent 3 and 5 hour period in overweight adults. A caveat to these findings is that the avocado contained an additional 112 kcal, which may have accounted for the observed increase in satisfaction and decreased desire to eat. Future trials are warranted to evaluate the effects of avocado intake on weight management in adults of varying BMIs and among insulin resistant individuals.