Eating macadamias does not lead to weight gain and may benefit certain cardiometabolic risk factors, like unhealthy blood lipid levels, according to a new study (1).

The randomised cross-over trial, involving 35 people, explored the effect of daily macadamia intake on body weight and composition, and other factors like plasma lipids (including total cholesterol and LDL-cholesterol) and glycaemic measures (such as insulin resistance).

About the study:

Study participants were between 40-75 years-old, and had abdominal obesity plus one extra cardiometabolic risk factor.

They ate their usual diet, but added macadamias (making up ~15% of their daily kilojoules, or between 35-59g/day) for eight weeks (‘intervention’ phase), and had another eight weeks without macadamia nuts (the ‘control’ phase).   

The research findings:

The study, by a team from Loma Linda University in California, found that macadamia intake did not lead to changes in waist circumference, body weight or percentage of body fat – despite an average increased energy intake of around 400kJ/day.

Including one to two servings of macadamias a day, even in people above a healthy weight, does not result in weight gain.

And compared to the control diet, consumption of macadamias led to reductions in total cholesterol, LDL (bad) cholesterol and apolipoprotein B (the main protein in LDL-cholesterol), and decreases in average weight and body mass index, although these were not statistically significant.

Macadamia intake did not impact glycaemic parameters, including measures of insulin resistance. 

The macadamia (‘intervention’) diet increased heart-healthy mono-unsaturated fat intake by 11.5%, compared with the control diet – but did not affect saturated fat intake.

A healthy handful (a 30g serve) is around 15 macadamias.

The research was funded by the global macadamia industry, and coordinated by the International Nut and Dried Fruit Council (INC), with the support of the INC World Forum for Nutrition Research and Dissemination.

It has just been published in the Journal of Nutritional Science.

Did you know? Fear of weight gain is a genuine barrier to Australians eating more nuts (2). Only two per cent of Australians eat the target 30g (a handful) a day – meaning that most are missing out on the protective health benefits of nuts (3).