A gut health scientist and dietitian has a simple rule for making balanced, tasty smoothies

A smoothie freshly blended by Megan Rossi.

Megan Rossi Fruit is nutritious but can be high in sugar.

When you blend fruit for a smoothie, it's easy to eat more portions than usual without feeling full.

Gut health scientist Megan Rossi has a special trick for finding the right balance.

Life can be tough for those of us who are partial to a smoothie but guided more by what's stuck to the bottom of the crisper drawer than any recipe.

One day, you pile your blender with fruits of every colour but get a sugar high like you've drunk a Frappuccino .

The next, you mix up kale, spinach, and celery, and pinch your nose to drink down the sludge that tastes like nothing but also dirt.

Megan Rossi, a gut health scientist , dietitian, and regular smoothie-drinker, has a simple rule that takes the guesswork out of creating a balanced smoothie: She simply adds two vegetables for every one type of fruit.

"Instead of it being too fruit-focused, I make it balanced with the veg," Rossi, a postdoctoral research fellow at King's College London, told Business Insider.

Rossi likes to have a smoothie in the afternoon as a snack and a quick way to eat around 10 extra grams of fiber a day.

Rossi eats around 50 grams of the hearty stuff daily because research suggests it can lower the risk of type 2 diabetes, colon cancer, and cardiovascular disease.

" Fiber is beneficial because it doesn't feed the human part of us.

It feeds the bacterial part of us.

And when the bacteria eat the fiber, they produce all these amazing chemicals which help things like our mental health, keep our gut lining strong, regulate our appetite, our hormone balance ," Rossi said.