Importance of high vegetable consumption in controlling weight
This project aimed to provide further scientific evidence on the role of vegetable consumption in weight loss. Food and nutrition scientists worked together to show that vegetables contain bio-active components (phytochemicals) that may influence the development of fat cells, they have a large bulk and low energy density that enables a greater feeling of fullness when eating compared to other food types in the same amounts, and they form an integral part of a healthy diet for weight loss. Analyses of Australian vegetables confirmed their phytochemical composition, and the foods analysed were found to be popular with participants in the weight loss trial (especially lettuce, potato, broccoli and onion). The satiety benefits were best when vegetables were prepared in larger pieces, and these effects supported the role of vegetables as good choices for snacks between meals. A bitter taste did not seem to have an effect on how much a person eats, but the volume of vegetables did. Participants in the year-long dietary trial were not hungry on a high vegetable diet and appeared able to continue the healthy eating plan with relative ease. They were able to keep off around 6 kg of body weight, and reduce waistlines at the same time. Future research can be developed from what was learnt here. Weight loss occurs when total energy (calories) consumed is less than energy expended. It is difficult to attribute weight loss to a single food group when this is a total diet effect, but we can combine knowledge to argue why vegetables are so valuable in this scenario. We can target more of the type of vegetables that are known to have greater levels of certain phytochemicals (e.g. chlorogenic acid) and growers can look to those vegetables and new cultivars. Future research can work on better biomarkers of vegetable intakes (for example from urine samples), that enable us to link weight loss effects with higher vegetable intakes, and we can be more targeted in our dietary advice for this purpose. We also need to know more about the effects of cooking and storage. We need to work out more ways to incorporate vegetables into every meal of the day, as well as snacks, to assist people in increasing their levels of vegetable consumption overall, and to be confident in preparing a wide variety of vegetables for all occasions.