Juicing fruit and vegetables is a popular way to get a get a quick ‘health fix’, but does come with the downside that they are less filling than eating the solid foods in the first place.
Eating more fruit and vegetables is the foundation stone of any healthy diet. One popular way to consume them is through juices. The one clear downside from drinking fruit and vegetables compared to eating them is the loss of fibre and other nutrients found in the skin and pulp. Juices though can be a quick, convenient and tasty way to get some of the health benefits of fruit and vegetables which is certainly better than not eating them at all.
One other potential downside to drinking rather than eating fruits and vegetables, is that the juice may not be as filling as eating solid food. It is also easier to drink the equivalent of many pieces of fruit in a few seconds when eating the same amount would take a lot longer, meaning there is more chance of over-consuming unneeded kilojoules.
To see if juices can lead to differences on appetite and later food consumption compared to solid food, 34 healthy lean and overweight people took part in a 21 week study . At different stages in the study, each person consumed a similar amount of fruit and vegetables (1680 kJ in total) daily in either solid (raw) form or as juices. No other changes to the participants’ diets were made.
When tested in a food laboratory, people who were overweight reported being significantly hungrier after a standard meal when consuming the juice in the lead up to it, compared to when they ate whole fruit. The post-meal hunger feelings of people of a healthy body weight where unaffected by the form of the fruit they consumed.
Having fruit in either solid or juice form before a meal though did mean less of the following meal was eaten, which is to be expected. Where it gets interesting though is that significantly less food was eaten in the meal by people who ate solid fruit before the test meal compared to those that had the juice.
Looking at how much food was eaten over the entire day, people who were obese ate significantly more food overall when they were drinking juice compared to eating solid fruit.
What it all means
This study gives some important clues to how consuming kilojoules in liquid form can be different from eating solid food. The overall effects of juice compared to solid foods on feelings of hunger and fullness were small overall, but the key aspect was that this was magnified in people who were overweight. For someone who is battling to keep their weight in check, then one positive change to make is to eat your fruit and vegetables from a plate, not a glass
Confused about the mixed soup of nutrition messages being stirred through the media? Tim maintains an active nutrition blog at www.thinkingnutrition.com.au  where you'll find the latest nutrition research and controversies discussed in straight forward language, distilling out what you need to know for your better health.