Intended for healthcare professionals

Views And Reviews Taking Stock

Rammya Mathew: Liquid diets offer promise, but we still need upstream solutions

BMJ 2019; 364 doi: (Published 03 January 2019) Cite this as: BMJ 2019;364:k5340
  1. Rammya Mathew, GP
  1. Wembley Park Drive Medical Centre, London
  1. rammya.mathew{at}
    Follow Rammya on Twitter: @RammyaMathew

When discussing dietary changes with patients I’m often greeted with blank expressions. It may seem simple in theory: eat healthy whole foods with less refined sugar and, dare I say it, fewer carbohydrates. But people find it hard to know where to start when it comes to modifying their diet, and they often have a sense of apathy about being able to lose weight.

The idea of using low calorie, ketosis inducing, liquid diets to lose weight has been trending for some time. Critics argue that such diets are unsustainable1 and unlikely to solve the growing obesity epidemic.2 Yet the results of two recent studies have suggested otherwise.34 Trial participants who restricted their oral intake to about 800 calories a day on a liquid diet achieved significant weight loss at 12 months, and an impressive 46% also achieved remission of type 2 diabetes.4

It’s not surprising that participants lose weight when restricting their calorie intake so drastically. But is there an advantage to taking such an aggressive approach versus standard dietary advice?

People find it hard to know where to start when it comes to modifying their diet

My sense is that, for some people, a liquid diet has the advantage of taking away the complexity of knowing which foods to eat, how much, and how often. The fact that it offers quick, noticeable results also instils a sense of “I can do this.”

Once people realise that they can lose weight and experience positive benefits to their physical and mental wellbeing, they’re perhaps better placed to take traditional lifestyle advice on board. Those trial participants had foods reintroduced after a period of 3-5 months and still managed to maintain weight loss—so, although liquid diets may be unsustainable in the long term, they may help instigate behaviour change.

At present any promise of a non-pharmacological intervention to reverse type 2 diabetes is certainly welcome news, but it does raise the question of why, as a nation, we understand so little about healthy eating that we need diets prescribed in the form of shakes and soups.

The celebrity chef Jean-Christophe Novelli recently spoke out about the need to reintroduce home economics lessons in schools so that young people might learn to cook healthy food. Could it be that the solution to the obesity crisis lies in the classroom rather than the consulting room?

Equipping people with the knowledge to make the right choices, and the skills to live and eat healthily, must be a better option in the long run than cultivating a growing dependence on liquid diets, slimming pills, and bariatric surgery.


  • Competing interests: I have read and understood BMJ policy on declaration of interests and declare that I have no competing interests.

  • Provenance and peer review: Commissioned; not externally peer reviewed.


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