Despite the skyrocketing popularity of weight-loss drugs such as semaglutide (Wegovy, Ozempic) and tirzepatide (Zepbound, Mounjaro), following an appropriate eating plan remains foundational to weight loss and management, according to presenters in a special session, “When, what and how of nutritional therapy,” at the European Association for the Study of Diabetes (EASD) 2025 Annual Meeting in Vienna.

The newest drugs are not widely available in many parts of the world and may come with side effects. In addition, patients are advised to take the drugs as part of an overall weight-loss program that includes diet and exercise. For these reasons and others, including patient preference, non-drug options are still very much needed.

Researchers discussed some of their latest work on nutrition therapy, including both expected and surprising findings.

5:2 Meal Replacement Wins in China

Among Chinese adults with overweight and obesity and early type 2 diabetes (T2D), a 5:2 intermittent fasting meal replacement (5:2 MR) intervention improved both glycemic outcomes and weight loss in the short term compared to metformin or empagliflozin. Therefore, this approach should be considered as a “strong first-line treatment option,” Dongni Yu, MD, of Beijing Hospital and the Chinese Academy of Medical Sciences, told meeting attendees.

Yu reported on exploratory outcomes related to the EARLY randomized, active-controlled trial, conducted in nine centers across China. The presentation focused on an analysis of body composition and abdominal fat distribution outcomes in 85 participants in one of the centers.

Per protocol, participants were randomly assigned to receive metformin (n = 28), empagliflozin (n = 28), or 5:2 MR (n = 29) for 16 weeks. Body composition was assessed using the InBody device, and energy spectrum CT was used to measure abdominal fat distribution.

Compared with the metformin and empagliflozin groups, the 5:2 MR group showed the most significant reductions in BMI (least-squares mean, -3.41 kg/m²), waist circumference (-8.83 cm), waist-to-hip ratio (WHR; -0.04), waist-to-height ratio (WHtR; -0.05), body fat percentage (BF%; -4.84%), abdominal cross-sectional area (ACSA; -66.05 cm2), subcutaneous fat area (-58.27 cm2), and liver-to-spleen ratio (0.43).

In addition, changes in BMI in that group showed linear associations and significant positive correlations with changes in WHR, WHtR, BF%, and ACSA.

“The structured nature of meal replacement may be a key factor in its success and safety,” suggested Yu, “but there are some limitations, such as single center, small sample size, and short-term study.” 

Time-Restricted Eating or Individualized Guidance?

Evelyn Parr, PhD, senior lecturer at Australian Catholic University in Melbourne, Australia, reported unpublished findings of her group’s work comparing outcomes of time-restricted eating (TRE) vs individualized dietetic guidance (IDG) on various measures of cardiometabolic health. 

An earlier randomized controlled trial by the group showed that, among patients with T2D, TRE was noninferior to IDG for reducing A1c, and that body mass was also reduced with both strategies. 

In her EASD presentation, Parr gave results of a study using a similar protocol in a larger group of adults with overweight or obesity at risk for developing T2D, according to the Australia-specific AUSDRISK score. The trial included 247 participants, with 124 randomized to TRE and 123 to IDG. TRE participants had a 9-hour eating window, with the latest eating occasion at 7 pm.

The intervention was delivered in five consultations to ensure it was implementable in Australia. “We mirrored what is available under a chronic disease management plan, where Medicare subsidizes five consultations in a 12-month period,” Parr explained. “For the 8-month follow up period, we provided text-message support to the individuals relative to the type of guidance that they received — TRE or IDG.”

The primary outcome was the change in A1c at 4 months. At that point, “unfortunately, we saw no difference between the two groups, and neither group improved their A1c,” Parr said. “This was slightly disappointing when you put in 3 years work to do this.”

Furthermore, when looking at secondary outcomes, there was no difference between the groups in terms of weight loss — about 2-3 kg each, she said — although participants managed to maintain the loss even after support was withdrawn. No between-group differences were seen in the percentage of lean muscle loss, which generally is around 20%-25% of total weight loss. BMI was reduced at 4 months, and that reduction was maintained, but there were no additional benefits between 4 and 12 months.

“We think TRE might be a pragmatic and feasible short-term alternative when participants or patients can't access dietetic support, or when they're resistant to dietetic support and need an alternative option to get them going,” Parr said.

It might also serve as a way for people at risk of diabetes to “scaffold into dietary changes,” she added. “What I mean is we had participants who, after a couple of consultations about TRE, wanted to know what foods they might change [to potentially improve results],” but the dietitians couldn’t respond because of the constraints of the trial.

One attendee suggested the finding might point to the importance of incorporating dietitians early on into the TRE intervention in future studies.

Mediterranean or Australian Diet?

Robel Hussen Kabthymer of Monash University, Melbourne, Australia, presented findings from his group’s randomized controlled trial comparing the effects of the Mediterranean diet vs the Australian Guide for Healthy Eating (AGHE) on body composition and glucose metabolism. The full study was recently published online in Diabetes, Obesity and Metabolism.

“Most studies investigating the potential benefits of the Mediterranean diet have been conducted among individuals with comorbidities such as T2D and obesity,” Kabthymer said. Those studies showed that the Mediterranean diet can reduce waist circumference and body fat percentage and improve muscle mass.

However, he said, few studies have been conducted among individuals without overt metabolic disorders, which might reveal whether the diet also has the potential to prevent both diabetes and obesity.

Therefore, his group undertook an 8-week trial among generally healthy individuals with a BMI above 18.5 comparing the effects of the Mediterranean diet to the AGHE diet.

They excluded individuals with chronic diseases, especially related to metabolism; pregnant or breastfeeding mothers; those with psychiatric disorders or eating disorders with unstable weight; and those who used medications directly or indirectly related with obesity or metabolism.

Participants following the AGHE received guidance in an hour-long session with a dietitian regarding the quantities and servings of each food group, tailored to their sex and age range.

The Mediterranean diet plan was derived from the Mediterranean Diet Model in Australia. Participants received a detailed sample Mediterranean meal plan, recipes, and educational material to assist with adherence. 

The researchers found that, compared to the AGHE, the Mediterranean diet resulted in a significant decrease in waist circumference (-1.3 cm), BF% (-1.8%), resting metabolic rate (-17.9 kcal/day), and fasting insulin concentration (-1.2 μIU/mL), along with an increase in body lean mass percentage.

“Our findings support the use of the Mediterranean diet in improving health outcomes related to obesity and metabolism, especially to prevent them before they happen,” Kabthymer said. “And it might also imply the need for translating some of the Mediterranean diet principles into our Australian dietary guidelines, although further evidence is still needed to cement the findings of our study.”

The presenters reported no conflicts of interest. 

Marilynn Larkin, MA, is an award-winning medical writer and editor whose work has appeared in numerous publications, including Medscape Medical News and its sister publication MDedge, The Lancet (where she was a contributing editor), and Reuters Health.