Such diets allow individuals to consume only liquid-based foods like juices, smoothies, soups, and protein drinks or supplements. But dietitian Jazlina Syahrul said while this approach can lead to significant weight loss and calorie deficits, long-term adherence may pose serious risks to both physical and mental health, especially if the diet is not properly planned or monitored by healthcare professionals.

She noted that inadequate protein intake can lead to muscle loss, causing one’s metabolic rate to decrease and making long-term weight loss more challenging.

“Liquid diets may also increase the risk of deficiencies in essential vitamins and minerals such as iron and calcium, while prolonged calorie restriction may lead to extreme fatigue, dizziness and reduced concentration,” she told Bernama.

“Furthermore, the lack of fibre in a liquid diet can also result in constipation and intestinal health problems,” she added.

She acknowledged that for some people, a liquid diet can help establish healthier eating habits before transitioning to a more balanced diet. However, one of its biggest challenges is the lack of eating satisfaction as it does not provide the chewing sensation needed for psychological fulfilment and appetite control.

“Without professional supervision, an unbalanced liquid diet may lead to nutrient deficiencies, including protein, vitamins and minerals. This could also result in rapid weight regain once an individual returns to his or her regular diet,” Syahrul noted.

Meanwhile, Dr Shanthi Kishnasamy, a senior lecturer in dietetics, expressed concern over the abundance of meal-replacement products on the market that have not been approved by the health ministry.

“This diet is not sustainable in the long run. Most individuals try it for a short period before stopping, leading to the ‘yo-yo’ effect where weight is lost and then regained,” she said.

Shanthi said liquid diets are usually prescribed as meal replacements for patients undergoing bariatric surgery – usually for a two-week period, during which they are given liquid food five to six times a day before the procedure.

For sustainable weight loss, Shanthi recommends focusing on calorie reduction by controlling portion sizes, adopting a diet rich in fruits, vegetables and whole grains, and increasing physical activity.

“It is better to follow the health ministry’s ‘quarter-quarter-half’ concept, a simple method to properly portion meals and ensure all essential food groups are included in each serving,” she added.

With this approach, half of your plate is filled with vegetables and fruits, a quarter with carbohydrates, and the remaining quarter with protein.