An obesity session at the European Renal Association Congress in Glasgow heard that medications such as the GLP-1 RAs were an important component of care in CKD but that lifestyle change and diet quality were also critical. 

Beyond BMI

Assistant Professor Beatriz Fernandez-Fernandez

Nephrologist Assistant Professor Beatriz Fernandez-Fernadez, from the Universidad Autónoma de Madrid, Spain, emphasised the importance of going beyond BMI in assessing patients.

“We have to assess phenotypes. We should measure waist-to-height ratio. We should measure waist-to-hip ratio. We can measure abdominal fat and body shape index …because that can indicate different obesity phenotypes.”

As an example, she said sarcopenic obesity – excess fat plus low muscle mass – was common in the elderly population.

She said a full assessment included CKD category, cardio-kidney-metabolic risks, frailty, diet quality, medications and barriers to change.

“I have to offer a plan: healthy eating, physical activity, weight loss goals, GLP-1 RAs, treating conditions such as BP and diabetes, behavioural support, bariatric surgery if needed, and of course long-term follow up, and we have to do this as a team. As a nephrologist, I can’t do everything on my own. I need dietitians, I need nurses, I need a psychiatrist sometimes because people just feel very anxious about eating and about lifestyle.”

She said an initial 5-10% weight loss was quite meaningful for metabolic status and for the CKD population. However, advice to “eat less, move more” was insufficient and stigmatising.

“In 2026, the question is not should I use lifestyle, should I use Mediterranean diet, or should I use them together. We have to use drugs, and we have to use behavioural lifestyle change. Why? Because the longer the patient is in their target weight range, the better the results will be.”

“I call this the incretin opportunity, because our patient will have a lot more opportunities to get better, and we have to consider starting these medications when the patient has a BMI of 27 and any obesity-related complications. Do not wait till the patient is more overweight or obese.”

She commented on quality of life results presented earlier in the meeting from the landmark FLOW study of semaglutide in patients with CKD and type 2 diabetes..

“Semaglutide helped those people not only to lose a lot of weight, not only to have a reduction of cardiovascular disease, cardiovascular mortality, of renal mortality, but those people felt better, and if your patient feels better, if they report benefits, they will be more adherent to medication and this will help them in the future,” she said.

Drug pipeline

Professor Hiddo Heerspink

Professor Hiddo Heerspink, from the University Medical Center Groningen in the Netherlands, told the meeting that obesity currently affected about 1 billion people and was expected to impact more than half of the world’s population by 2050.

“The problem is that obesity is one of the main causes of type two diabetes. There are now about half a billion people with type two diabetes, and in 25 years more than a billion people will have type two diabetes.

But obesity’s impact on kidney disease was not just limited to its impact on insulin resistance and type 2 diabetes.

“Obesity affects renal haemodynamics, causes hypertension, and causes inflammation and these effects directly influence microvascular damage, can cause albuminuria, and that leads to kidney disease,” he said.

Professor Heerspink said most relevant drug development since the 1990s had focussed on the GLP-1 RAs but that was all about to change.

“Two years ago we saw the results of the FLOW trial, a clinical trial with semaglutide, and I expect that more of these medications will become available in the next couple of years. I believe that these drugs have profound benefits for the kidney.”

He said tirzepatide, a dual GIP and GLP-1 receptor agonist, had shown to be more effective in lowering HbA1c and body weight compared to any dose of semaglutide.

“Is there then an added value of targeting GIP beyond GLP-1 or is tirzepatide just a very potent GLP-1 receptor agonist and GIP alone has no effect at all?” he asked.

Professor Heerspink said an unpublished study comparing the GLP-1 RA dulaglutide with the GIP receptor agonist macupatide, or a combination of the two molecules, provided some insight.

The study, presented at EASD in 2024, showed that both dulaglutide and macupatide reduced body weight but the combination was much more effective. Meanwhile, the effects on HbA1c did appear not to be additive, suggesting that the GIP appears to have a particular effect on body weight.

He outlined a number of other agents being trialled including cotadutide, survodutide and the ‘triple agonist’ retratrutide targeting GLP-1, GIP and glucagon.

“A press release from two weeks ago shows that in people with overweight or obesity treated for 80 weeks, retratrutide reduces body weight ranging from 19% to 28% or weight reductions of up to 30 kg versus two kg with placebo. These are weight losses in the range of bariatric surgery,” he said.

He said a pre-specified extension out to 104 weeks found retratrutide 12 mg caused a reduction in body weight from baseline of 38.5 kg. Even patients who were switched from placebo at week 80 for 24 weeks on retrutrutide had a 22.6 kg weight loss.

“It’s a very potent drug… but that’s why we should target and uptitrate these drugs stepwise, not only in terms of safety to maximise tolerability, but also to monitor body weight. Importantly, retratrutide has many more effects than only lowering body weight – it reduces HbA1c, reduces systolic blood pressure by 9 – 15 mmHg, reduces LDL cholesterol by about 17%, and in the phase two study reduces UACR by at least 30% and more recent studies suggest even larger reductions,” he said.

Diet quality

Dr Carla Avesani, a renal dietician and researcher from the Karolinska Institutet, Sweden, told the meeting that consumption of ultraprocessed foods was driving obesity around the world.

Their convenience and hyperpalatability meant they were increasing energy intake and replacing nutrient dense food.

Their poor nutrient profile, including high energy, sugars, salt and saturated/trans fats also promoted other chronic diseases including hypertension, cardiovascular disease and CKD, while their additives such as emulsifiers, colour and preservatives may disrupt microbiota and increase inflammation and metabolic risk.

There was also evidence of a direct effect on renal tubular cells.

She said a 2024 meta-analysis [link here] had shown that individuals with a higher intake of ultraprocessed food (UPF) in their diet have an 18% higher chance of CKD overall. As well, for each 10% increase in ultraprocessed food, there was a 7% higher risk of developing CKD.

“We formulated this theory that UPFs are double trouble in CKD, because for a person that already has chronic kidney disease, ingesting a diet such as those with high UPF content which has very poor quality can further complicate the CKD complications that these patients already have like metabolic acidosis, dysbiosis, hyperkalemia, hyperphosphatemia, and insulin resistance.”

Dr Avesani said ultraprocessed food intake has been estimated at about 30% of the diet in European countries – higher in the UK and Sweden and lower in Italy and Romania. The five most consumed classes were bakery goods, sausages, ready-to-eat foods, margarines and sausages.

She noted that 2024 KDIGO guidelines for CKD [link here] already advise healthy and diverse diets, higher consumption of plant-based foods and a lower consumption of ultraprocessed foods.

However the findings from a 2026 KDIGO controversies conference on obesity and CKD did not specifically mention ultraprocessed foods and instead only recommended energy-reduced dietary patterns compatible with a Mediterranean-style diet.

Dr Avesani said an intervention in Stockholm – providing patients with weekly food baskets containing only non-processed food of fruit, vegetables, nuts, legumes, and servings of either fish, chicken, or eggs – substantially decreased intake of ultraprocessed foods.

She said the costs of such a dietary intervention especially in more vulnerable patients would be offset by savings on prescribed medications.