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Juicing and smoothies: what plant based doctors say
Juicing and smoothies on a plant based diet: what McDougall, Esselstyn, Barnard, Goldhamer and other doctors say, where they agree and differ.
Updated . For education only, not medical advice.
Our view
Juicing and blending both start from whole plants, but they change them: a juicer throws most of the fiber away, and a blender breaks it up so the food no longer needs chewing12. Goldhamer and McDougall both see juice as a step away from whole food that makes it easier to take in more calories than the fruit or vegetable itself would give34.
We give most weight to the low-fat clinicians who have fed patients this way for decades, and for everyday eating they point the same way: eat the plant whole and chew it1456. Neal Barnard and Hana Kahleova are milder about pure fruit juice, citing studies in which it went with weight loss or lower heart risk, so juice remains a real point of debate rather than a settled harm78.
Juice also has narrower uses among these doctors: Goldhamer’s center gives mostly vegetable juices in juice fasts, Doug Lisle has suggested a short juice fast to reset the taste buds, and Peter Rogers drinks beet juice before exercise91011.
Where they agree
Most of these doctors put the whole food first: Esselstyn’s FAQ says not to juice, Ornish told readers with diabetes in 2014 to pick the whole fruit, and even Barnard, lenient on juice, said in 2024 that eating the fruit itself is best11213. Rogers agreed in 2026 that whole foods beat blended ones14.
They also agree that fiber is the reason: Esselstyn’s FAQ says fruit sugar loosed from its fiber gets absorbed too quickly, Ornish wrote that fiber slows the climb in blood sugar, Barnard explained in 2020 that blending an apple digests it partly in advance, and Rogers said in 2026 that a smoothie loses most of its fiber1121516.
Fullness is the other shared worry: McDougall cited a 1977 experiment in which apple juice went down eleven times faster than whole apples, satisfied less and raised insulin more, and Novick used the same apple comparison in a 1999 column176. Lisle told of a Goldhamer patient whose weight loss stalled until he gave up the gallon of apple juice he was drinking each day18.
Where they differ
The doctors split on four points: whether pure fruit juice is a problem at all, whether smoothies still count as whole food, when juice has a use, and what risks come with some juices and machines1922021.
Fruit juice and weight
McDougall concluded in 2007 that trading whole food for its juice will, at the least, favor weight gain, and in 2024 he said juicing sends insulin higher422. Novick wrote in 2011 that juice on average carries about as many calories and as much sugar as soda, and a year later he named liquid calories as something to cut or strictly limit when weight loss stalls2123. Barnard took the other side in March 2024: Harvard data tied citrus juice, not only whole citrus, to weight loss, its glycemic index is modest, and he found juice not guilty719. Kahleova sits between them: in 2022 she set fresh squeezed juice apart from sugary drinks with little juice in them while warning that people drink too much, and in 2024 she pointed to studies in which pure fruit juice lowered heart risk248.
Smoothies
Esselstyn’s FAQ says to avoid smoothies because pureed food skips chewing, and in a 2023 talk he asked heart patients to chew their greens six times a day rather than drink them225. Lisle argued in 2016 that grinding food makes it about 12.5% cheaper for the body to digest, which in effect raises its calorie density, and Chef AJ cited that figure in 2022 when she advised against smoothies for weight loss2627. Others are more relaxed: Kahleova in 2022 counted a whole fruit smoothie among the better options because it keeps the fiber, Rogers said in 2026 that a blender is welcome if it gets someone eating more plants, and Goldhamer uses smoothies to help underweight patients gain28145. On fiber Rogers disagrees with Kahleova, saying in 2026 that blending strips most of it out16.
Juice as a tool
Goldhamer draws a line between fasting, which at his center means water alone, and juice fasting, which he regards as a form of feeding29. In 2025 he said a juice fast works more slowly than water but carries less risk for certain patients, for instance anyone who has to stay on a blood thinner, and said his center’s juices are mostly vegetable with a little fruit, watermelon with celery for example209. In a 2019 talk Lisle suggested two or three days on juice, carrot and apple for instance, to give the taste for fat and salt a rest10. Ornish said in 2014 that one of his studies pointed to a glass of pomegranate juice each day as possibly starting to undo heart disease within months, and Rogers drinks beet juice before workouts and long talks3011.
Risks of juices and machines
Novick wrote about arsenic in apple juice in 2011 and in 2012 named apple and grape juice among foods high in it2131. Rogers grew uneasy about carrot juice in 2025 after reading that one large bottle held some 800% of the recommended daily vitamin A, a vitamin that builds up in body fat3233. He also warned in 2022 that loud juicers and blenders can hurt hearing, and in 2026 that plastic blender jugs shed microplastics, so he prefers glass3435. McDougall’s 2007 newsletter added a cost point: pricey exotic juices such as goji and noni had almost no human research behind them, while cheap cranberry juice had more36.
What each expert says
JMJohn McDougall
In his December 2007 newsletter on juicing, McDougall argued that Western illness comes from excess rather than missing nutrients, so a bottle of extra vitamins cannot fix it37. In his judgment juice has left the category of whole plant foods, and choosing it over the fruit or vegetable tends to add weight4. Speaking with Chef AJ in 2024, he said juicing frees more calories along with the vitamins and raises insulin22.
Esselstyn’s FAQ, as read in 2026, rules out juicing and smoothies alike: juice because fruit sugar without its fiber is absorbed too fast, smoothies because blended food is never chewed12. In a 2023 talk he wanted heart patients chewing leafy greens six times a day, not drinking them25.
Barnard is the most forgiving on juice: in March 2024 he rated canned concentrate and fresh squeezed citrus juice about equal and cleared juice of blame, citing Harvard data on weight loss719. In his 2024 Power Foods talk he still put the whole fruit first13. In 2020 he explained that a blender does part of the digesting ahead of time, so the sugar in fruit enters the bloodstream sooner15.
Ornish’s view depends on the juice: in a 2014 column for readers with diabetes he advised the whole fruit over its juice, because its fiber makes blood sugar climb more gently12. In a 2014 program video he said his own study found that a daily glass of pomegranate juice might start to undo heart disease in a matter of months30.
For everyday eating, Goldhamer said in 2024 that juicing fruit strips its fiber and makes overeating easier, and that people trying to lose weight do better on whole food, while smoothies can help the underweight gain35. In clinical fasting he treats juice as a gentler option than water alone, with juices made mostly from vegetables209.
Rogers called juicing overrated in 2022, something people hope will solve everything fast, though it may help a little at first, and he dislikes the noise of the machines34. In 2026 he said whole foods beat blended ones, but a blender that adds more plants is welcome, preferably with a glass jug1435. He drinks beet juice before workouts but turned wary of carrot juice in 2025 because of its vitamin A1132.
To Novick juice is processed food: in 2011 he wrote that it is no health food and on average matches soda for calories and sugar21. His 1999 fiber column used the apple comparison, in which the juice is gone in seconds and hunger returns far sooner than after the whole fruit6. His 2012 tips for a stalled diet told readers to drop caloric drinks or keep them to a minimum23.
On a 2022 episode of her show Chef AJ said she does not recommend smoothies for weight loss, because liquid calories register less and smoothies tend to hold more fruit than vegetables2738. For anyone who wants one anyway, she suggested keeping it chunky, or blending a mostly vegetable salad smoothie that is closer to gazpacho38.
Kahleova takes a middle position: in 2022 she said freshly squeezed juice differs from sugary drinks, but warned that people overdo it and that boxed juice loses its fiber24. She preferred homemade juice, or whole fruit blended so the fiber stays28. In 2024 she questioned listing pure fruit juice among unhealthy plant foods8.
Lisle sees processing as a calorie density issue: in 2016 he said that fruit put through a blender is not quite the same food, since ground food costs less to digest26. In 2017 he described a Goldhamer patient who stopped losing weight while drinking a gallon of apple juice a day18. In a 2019 TEDx talk he offered a short juice fast as one way to win back taste sensitivity10.
For everyday eating we follow most of these doctors and eat fruits and vegetables whole and chewed rather than juiced or blended145. Whether juice or smoothies suit you, and whether a juice fast makes sense, are questions for your own doctor. This page is education, not medical advice.
Each small number links to its reference below: the video at the exact second, or the page where it was said.