A small UK trial found that daily consumption of avocado changed abdominal adiposity distribution among females, but had no influence on glucose tolerance in either men or women, found a study in The Journal of Nutrition.
One hundred and five adults with overweight and obesity participated in a randomised controlled trial that provided one meal a day for 12 weeks. Women who ate avocado as part of their daily meal had a reduction in deeper visceral abdominal fat.
The study was led by Naiman Khan, an Illinois professor of kinesiology and community health, and funded by the Hass Avocado Board.
“The goal wasn't weight loss; we were interested in understanding what eating an avocado does to the way individuals store their body fat. The location of fat in the body plays an important role in health,” Khan said.
“In the abdomen, there are two kinds of fat: fat that accumulates right underneath the skin, called subcutaneous fat, and fat that accumulates deeper in the abdomen, known as visceral fat, that surrounds the internal organs. People with a higher proportion of that deeper visceral fat tend to be at a higher risk of developing diabetes. So we were interested in determining whether the ratio of subcutaneous to visceral fat changed with avocado consumption.”
The participants were divided into two groups. One group received meals that incorporated a fresh avocado, while the other received a meal that had nearly identical ingredients and similar calories but no avocado.
At the beginning and end of the 12 weeks, the researchers measured participants' abdominal fat and their glucose tolerance, a measure of metabolism and a marker of diabetes.
Female participants who consumed an avocado a day as part of their meal had a reduction in visceral abdominal fat — the hard-to-target fat associated with higher risk — and experienced a reduction in the ratio of visceral fat to subcutaneous fat, indicating a redistribution of fat away from the organs.
However, fat distribution in males did not change, and neither males nor females had improvements in glucose tolerance.
“While daily consumption of avocados did not change glucose tolerance, what we learned is that a dietary pattern that includes an avocado every day affected how people store body fat in a beneficial manner for their health, but the benefits were primarily in females,” Khan said. “It's important to demonstrate that dietary interventions can modulate fat distribution. Learning that the benefits were only evident in females tells us a little bit about the potential for sex playing a role in dietary intervention responses.”
The researchers said they hope to conduct a follow-up study that would provide participants with all their daily meals and look at additional markers of gut health and physical health to get a more complete picture of the metabolic effects of avocado consumption and determine whether the difference remains between the two sexes.
“Our research not only sheds a valuable light on benefits of daily avocado consumption on the different types of fat distribution across genders, it provides us with a foundation to conduct further work to understand the full impact avocados have on body fat and health,” said study co-author Richard Mackenzie, a professor of human metabolism at the University of Roehampton in London.
“By taking our research further, we will be able to gain a clearer picture into which types of people would benefit most from incorporating avocados into their diets and deliver valuable data for health care advisers to provide patients with guidance on how to reduce fat storage and the potential dangers of diabetes,” he said.
Researchers at the University of Florida and Eastern Illinois University also collaborated on this work.
Study details
Avocado Consumption, Abdominal Adiposity, and Oral Glucose Tolerance Among Persons with Overweight and Obesity
Naiman A Khan, Caitlyn G Edwards, Sharon V Thompson, Bridget A Hannon, Sarah K Burke, Anne D M Walk, Richard W A Mackenzie, Ginger E Reeser, Barbara H Fiese, Nicholas A Burd, Hannah D Holscher.
Published in The Journal of Nutrition on 9 September 2021
Abstract
Background
Although intake of Hass avocado has been cross-sectionally linked to lower abdominal obesity, knowledge of the effects of avocado consumption on abdominal adiposity and glycemic outcomes remains limited.
Objective
The effects of avocado consumption on abdominal adiposity, insulin resistance, oral-glucose-tolerance test (OGTT), and estimated β-cell function were evaluated.
Methods
A total of 105 adults aged 25–45 y (61% female) with BMI ≥25 kg/m2 were randomly assigned to an intervention (N = 53) that received a daily meal with 1 fresh Hass avocado or a control (N = 52) that received an isocaloric meal with similar ingredients without avocado for 12 wk. DXA was used to assess the primary outcomes of abdominal adiposity [visceral adipose tissue (VAT), subcutaneous abdominal adipose tissue (SAAT), and the ratio of VAT to SAAT (VS Ratio)]. Fasted glucose and insulin were used to assess the primary outcomes of insulin resistance (HOMA-IR), and insulin sensitivity (Matsuda index) and β-cell function (Insulinogenic index) were estimated using an OGTT. Changes between groups were compared using an ANCOVA. Secondary analyses were conducted based on sex.
Results
The control group exhibited a greater reduction in SAAT [–54.5 ± 155.8 g (control) compared with 17.4 ± 155.1 g (treatment), P = 0.017] and increase in VS Ratio [0.007 ± 0.047 (control) compared with –0.011 ± 0.044 (treatment), P = 0.024]. Among females, the treatment group exhibited a greater reduction in VAT [1.6 ± 89.8 g (control) compared with –32.9 ± 81.6 g (treatment), P = 0.021] and VS Ratio [0.01 ± 0.05 (control) compared with –0.01 ± 0.03 (treatment), P = 0.001]. Among males, there was no significant difference between groups in changes in abdominal adiposity or glycemic outcomes.
Conclusions
Daily consumption of one fresh Hass avocado changed abdominal adiposity distribution among females but did not facilitate improvements in peripheral insulin sensitivity or β-cell function among adults with overweight and obesity.
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