Fruit Juice
Fruit juice might seem like an easy addition to a smoothie, especially if you're hoping for a fruitier flavor and need some extra liquid for the smoothie texture.
Unfortunately, adding fruit juice to a smoothie is a bad idea--particularly if you are hoping to lose weight. Fruit juice is not as filling as fruit, meaning you will most likely be hungry again soon.
Plus, according to UC Davis Health, "The more concentrated sugar and calories in fruit juice can lead to obesity and inappropriate weight gain."
Not only are juices higher in sugar, they also contain less of the healthy nutrients you might be hoping for by incorporating more fruits into your diet.
For example, according to Healthline, "In one study, store-bought orange juice had 15% less vitamin C and 27% less folate than home-squeezed orange juice."
That's not all. There are also less antioxidants.
Healthline continues, "One study found that — compared to unprocessed orange juice — pasteurized orange juice had 26% less antioxidant activity immediately after heat processing and 67% less antioxidant activity after about a month in storage."
Although you may be able to avoid this with hand squeezed OJ, that is not very time sensitive--and you would be better off just adding oranges to your smoothie and skipping the juicing step altogether.
With that in mind, keeping fruit juices out of your smoothies is a good idea, especially for those who want to lose weight.
Instead, stick to adding whole fruits to your smoothie, and opt for something like oat milk to get the texture right.