Ketogenic Diet Cut Liver Fat by 67% in a Randomised Trial
Key Takeaways:
- People with obesity who followed a ketogenic diet reduced their liver fat by an average of 67%, compared with an average reduction of 45% in both the Mediterranean and low-fat plant-forward groups – even though all three groups lost a comparable amount of weight.
- Around half of the participants following the ketogenic diet no longer met the criteria for prediabetes by the end of the study, compared with 29% in the Mediterranean group and 7% in the plant-forward group.
- Despite obtaining 73% of their calories from fat, participants in the ketogenic group showed no increase in blood fat or cholesterol levels, alongside the largest rise in glucagon and the steepest fall in blood insulin of the three groups.
Carbohydrate restriction appeared to add benefits beyond weight loss
A very low-carbohydrate, high-fat diet may deliver stronger metabolic benefits for people with obesity than either a Mediterranean diet or a low-fat diet, according to a clinical trial published on 27 August in the Cell Press journal Cell Metabolism. After four to five months on a ketogenic (or “keto”) diet, about half of the participants with obesity and prediabetes no longer met the criteria for prediabetes.
“We know weight loss can improve metabolic health in people who are obese,” says Samuel Klein, the study’s corresponding author at Washington University School of Medicine in St. Louis, Missouri. “Our data suggest that if you have high liver fat content and prediabetes, reducing carbohydrate intake can have important therapeutic effects on metabolism beyond just weight loss alone.”
The distinction matters clinically. Weight loss itself is known to improve metabolic markers, so the open question has been whether the composition of a diet contributes anything further once the amount of weight lost is held constant. This trial was designed to test exactly that.
Comparing three widely used weight loss diets
An estimated 40% of adults in the United States have obesity. Doctors often recommend low-fat, low-carbohydrate or Mediterranean diets for weight loss, but researchers have not known whether one approach provides extra metabolic advantages beyond the effects of losing weight.
The three diets differ sharply in how much carbohydrate and fat they provide:
- A low-carbohydrate diet, also known as the Atkins or ketogenic diet, greatly restricts carbohydrates. A ketogenic diet can include foods rich in saturated fat, including animal products.
- A low-fat diet, by contrast, can obtain as much as 70% of its energy from carbohydrates.
- A Mediterranean diet emphasises plant-based foods such as vegetables, olive oil and nuts, along with moderate amounts of fish and dairy.
To compare their effects, Klein and his colleagues enrolled 42 people with obesity, prediabetes and fatty liver disease in a clinical trial. Participants were randomly assigned to follow a ketogenic diet, a Mediterranean diet, or a low-fat, plant-forward diet. The research team supplied all of their food, and participants met with a dietitian every week to help them stay on their assigned eating plan.
That level of support is worth noting. Providing every meal and offering weekly dietetic contact removes much of the adherence variability that undermines free-living diet studies, which strengthens confidence that the differences observed between groups reflect the diets themselves rather than differences in how closely people managed to follow them.
Matching weight loss across the three groups
The ketogenic diet supplied just 4% of calories from carbohydrates and 73% from fat. In the Mediterranean group, 50% of calories came from carbohydrates and 35% from fat. The plant-forward diet provided 70% of calories from carbohydrates and 15% from fat.
Researchers adjusted calorie intake for each person so that participants in all three groups would lose about 10% of their body weight. Reaching that target took roughly four to five months.
By the end of the study, participants in every diet group had significantly reduced their body fat. Insulin sensitivity also improved across all three groups, helping the body control blood sugar more effectively. In other words, all three approaches worked – the question was whether any of them worked better than the others once weight loss was equalised.
The ketogenic diet produced the largest fall in liver fat
Despite similar weight loss, the ketogenic diet produced the strongest changes across several measures of liver and metabolic health. Liver fat fell by an average of 67% among people following keto, compared with an average reduction of 45% in both the Mediterranean and plant-forward groups.
The researchers also tracked participants’ metabolism over a 24-hour period by repeatedly analysing their blood. People in the ketogenic group showed the largest rise in glucagon, a hormone that helps reduce fat stored in the liver. They also had the greatest decline in blood insulin levels, another change that can help lower liver fat, compared with participants following the other two diets.
Together, the hormonal findings offer a plausible mechanism for the liver fat result: lower circulating insulin and higher glucagon both shift the liver away from storing fat, and both are the expected consequence of sharply restricting carbohydrate intake.
Blood fats did not rise on the highest-fat diet
One of the more counter-intuitive results concerned the lipid profile of the ketogenic group, whose diet contained by far the most fat and could include saturated fat from animal products.
“The most surprising finding was that participants in the ketogenic diet group didn’t experience an increase in blood fat or cholesterol levels despite consuming the most fat,” says Max Petersen, the study’s first author at Washington University School of Medicine.
Prediabetes improved most in the ketogenic group
After the weight loss intervention, about 50% of participants following the ketogenic diet no longer met the criteria for prediabetes. That compared with 29% of those on the Mediterranean diet and 7% of those following the plant-forward diet.
The researchers were careful to position dietary composition alongside, rather than against, current pharmacological options for people living with obesity.
“GLP-1-based medications have revolutionized the therapy of obesity. We now have a very effective pharmacotherapy for achieving significant weight loss,” Petersen says. “But in addition, our study shows that the specific composition of the diet can give you added benefits.”
What the findings mean for everyday practice
For healthcare professionals supporting people with obesity, prediabetes or fatty liver disease, the practical implication is that the content of a weight loss plan may deserve as much consultation time as the calorie target attached to it. Two people can lose the same 10% of their body weight and still arrive at meaningfully different liver fat and glycaemic outcomes.
This is the kind of nuance that clinicians increasingly need to be able to explain confidently in a short appointment, and it is a core focus of continuing professional development in nutrition. The College of Contemporary Health’s Nutrition & Weight Management Essentials CPD short course is designed for practitioners who want to strengthen their grounding in evidence-based nutrition and weight management before applying it in conversations with patients.
It is also worth keeping the study’s limits in view. This was a small trial of 42 people, conducted under closely controlled feeding conditions with weekly dietetic support and all food provided. Whether the ketogenic advantage persists in free-living conditions, over longer periods, and across broader populations remains to be established.
The research was supported by the National Institutes of Health and the Foundation for Barnes-Jewish Hospital.
CCH insight
Findings like these are only useful at the point where a clinician can translate them into a realistic, personalised plan with a patient. Nutrition & Weight Management Essentials is a CPD-accredited short course from The College of Contemporary Health, developed for healthcare professionals who want a practical, evidence-informed foundation in nutrition and weight management.
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Higher Coffee Intake Linked to Lower Visceral Fat and Greater Muscle Mass
Key Takeaways:
- Higher habitual coffee intake was associated with lower total and visceral fat and greater skeletal muscle mass, despite a similar BMI.
- Coffee intake was linked to lower branched-chain amino acids in both sexes, and to sex-specific differences in testosterone and SHBG.
- The study was observational, so it cannot show that drinking coffee caused any of the differences identified.
A familiar drink with poorly understood biology
Coffee is consumed around the world every day, and earlier research has associated coffee drinking with a reduced risk of conditions including type 2 diabetes and cardiovascular disease. What has remained unclear is why. Scientists still do not fully understand the biological processes that might explain those connections, which has made it difficult to interpret the epidemiological signal.
New research from Finland now suggests that regular coffee consumption is associated with healthier body composition, favourable metabolic markers, and distinct patterns involving sex hormones in men and women.
What the researchers examined
Researchers at the University of Oulu analysed information from 2,264 people who were 46 years old and taking part in the Northern Finland Birth Cohort 1966. The team investigated how participants’ usual coffee intake related to circulating metabolites, indicators of cardiometabolic risk, and sex hormone levels.
Studying a single birth cohort at a single age has a particular advantage: it removes age itself as a source of variation, allowing differences between people with higher and lower coffee intake to stand out more clearly.
Lower body fat and greater muscle mass
People who consumed more coffee tended to have lower levels of both total body fat and visceral fat, along with greater skeletal muscle mass.
Notably, these differences appeared even though participants with higher and lower coffee intake had a similar body mass index (BMI). That detail matters clinically. BMI cannot distinguish fat mass from lean mass, or subcutaneous fat from the visceral fat that sits around the abdominal organs and carries the stronger association with cardiometabolic risk. Two people with an identical BMI may therefore have meaningfully different metabolic profiles, and in this cohort coffee intake tracked with that hidden difference rather than with weight itself.
A metabolic marker associated with diabetes risk
Higher coffee consumption was also associated with lower circulating concentrations of branched-chain amino acids in both men and women. When chronically elevated, these biomarkers have previously been associated with insulin resistance and a greater risk of developing type 2 diabetes.
This finding sits alongside the body composition results rather than separately from them, since visceral fat and insulin resistance are themselves closely linked.
Different hormonal patterns in men and women
Some of the clearest differences appeared among men. Greater coffee consumption was associated with a more favourable glucose-insulin profile, higher levels of total and bioavailable testosterone, and greater concentrations of sex hormone-binding globulin (SHBG). However, free testosterone and the free androgen index were modestly lower.
The hormonal associations were less extensive in women. Higher coffee consumption was mainly associated with increased SHBG and lower measures of free androgens.
The common thread across both groups was SHBG, the carrier protein that binds circulating sex hormones and influences how much is biologically available to tissues. Higher SHBG has itself been studied in relation to metabolic health, which makes it a plausible point of connection between the hormonal and cardiometabolic findings.
“Coffee is consumed by millions of people every day, yet we still know surprisingly little about how it relates to our metabolism and hormones. What stood out in our findings was a distinct hormonal signature that didn’t disappear even after we took into account BMI and lifestyle factors, with several of these associations differing between men and women,” says Luca Verroest, lead author of the study and Doctoral Researcher at the University of Oulu.
Why the hormonal findings could matter
The findings raise the possibility that hormonal pathways could help explain some of the previously observed relationship between coffee consumption and metabolic health.
Because the research was observational, however, it cannot establish that drinking coffee directly caused any of the biological differences identified in the study. People who drink more coffee may differ from those who drink less in ways the analysis could not fully capture, and the direction of any relationship cannot be determined from data collected at a single point in time.
For clinicians, the more immediately useful message concerns interpretation rather than advice. Findings of this kind reinforce how much a single anthropometric measure can conceal, and how dietary patterns, body composition, and endocrine markers interact when assessing cardiometabolic risk. Practitioners who want to strengthen that interpretive skill set often look to structured CPD such as the College of Contemporary Health’s Nutrition & Weight Management Essentials short course, which examines how dietary intake relates to body composition and metabolic health in everyday practice.
Finland as a study setting
The setting also makes the research especially relevant. Finland ranks among the world’s highest coffee-consuming countries, with average annual consumption of approximately 11.8 kilograms (26 pounds) per person. A population with high and widely varying intake offers greater statistical range than one in which most people drink little coffee at all.
What happens next
Researchers say the results offer a starting point for studies designed to determine whether coffee itself produces these biological changes and, if so, which compounds may be responsible. Scientists are currently investigating these questions using animal models, with the longer-term aim of moving towards human intervention studies.
Additional research will be necessary before the findings can be used to shape dietary recommendations. For now, the study contributes a mechanistic hypothesis rather than a change in practice.
The study, “Associations of habitual coffee intake with testosterone and cardiometabolic markers: the Northern Finland Birth Cohort 1966 study,” was published in the European Journal of Nutrition.
CCH insight
Body composition, dietary patterns, and metabolic markers rarely tell a complete story in isolation, and BMI alone can mask clinically important differences. The College of Contemporary Health’s Nutrition & Weight Management Essentials short course helps healthcare professionals interpret these measures together and apply nutritional evidence confidently in patient-facing practice.
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Source: University of Oulu, Finland
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Visceral Fat and Biological Ageing: New Research Links Deep Belly Fat to Faster Cellular Ageing
Key Takeaways:
- A study of nearly 4,800 adults aged 45 to 69 from the Busselton Healthy Ageing Study found that higher levels of visceral fat – the fat stored deep within the abdomen – were associated with faster biological and cellular ageing in both men and women.
- Among female participants, greater visceral fat was also linked to shorter telomere length, a recognised marker of cellular ageing.
- The associations held even after researchers adjusted for overall body fat, body mass index (BMI), waist circumference and lifestyle factors, suggesting visceral fat exerts an effect beyond general measures of body composition.
New research from The University of Western Australia suggests that visceral fat, the type of fat stored deep within the abdominal cavity and wrapped around internal organs, may contribute to faster biological ageing in middle-aged adults independently of overall body weight or general obesity measures. The findings were published in the journal Obesity.
A large population-based analysis
The study was co-authored by Adjunct Associate Professors Jennie Hui and Kun Zhu, both of The University of Western Australia, with the analysis led by Mr Riorden O’Shea, a resident medical officer with the WA Country Health Service. Researchers drew on data from nearly 4,800 participants – 2,614 of them women – aged between 45 and 69 years, all enrolled in the Busselton Healthy Ageing Study.
The team examined how visceral fat related to markers of biological ageing, including indicators of cellular ageing such as telomere length. Telomeres are the repetitive DNA sequences that cap the ends of chromosomes; their progressive shortening over time is widely regarded as a key biological signature of cellular ageing.
The analysis found that greater visceral fat was associated with accelerated biological ageing in both men and women. In women, higher visceral fat was additionally linked to shorter telomere length.
“Our study shows that visceral fat is associated with faster biological and cellular ageing,” said Associate Professor Hui, who is Director of the Busselton Health Study Laboratory. “Understanding what drives faster ageing helps us find better ways to stay healthy for longer.”
An effect that holds after adjusting for other body measures
A central finding of the study is that the link between visceral fat and accelerated ageing persisted even when researchers controlled for other indicators commonly used to assess body composition and adiposity.
“Importantly, these associations remained significant even after accounting for overall body fat, body mass index, waist circumference and lifestyle factors,” Associate Professor Zhu said.
This suggests that visceral fat may have implications for ageing that are not fully captured by routine measures such as BMI or waist circumference – measures that have long been criticised for failing to distinguish between fat stored just under the skin and the metabolically distinct fat located deep within the abdomen.
Why visceral fat behaves differently
Visceral fat is biologically active in ways that subcutaneous fat is not. It secretes inflammatory signalling molecules and contributes to a chronic, low-grade inflammatory state that researchers have increasingly linked to chronic disease and accelerated ageing.
“Visceral fat is metabolically active, secreting a range of pro-inflammatory proteins, which contribute to systemic inflammation and metabolic stress,” Associate Professor Zhu said.
She also noted a practical point that is likely to resonate in clinical settings: visceral fat does not require specialised, costly imaging to assess. “It can be easily measured using imaging technology, which is widely used in routine bone density scans,” she said. This positions visceral fat as a metric that could plausibly be folded into existing clinical workflows without significant additional cost.
The value of long-running cohort data
The findings rest on one of the most established population-health datasets in the world. Established in 1966, the Busselton Health Study is internationally recognised as one of the longest-running population health programmes ever conducted, providing a rich longitudinal dataset that continues to support research into chronic disease and healthy ageing.
Mr O’Shea, who led the analysis, said the project demonstrated the enduring scientific value of sustained cohort studies of this kind. “Access to high-quality longitudinal data allowed us to better understand how clinical risk factors relate to long-term health outcomes,” he said.
Implications for healthier ageing
The findings reinforce a growing body of evidence that abdominal fat distribution – not just total body fat – is an important consideration in healthy ageing. While the study is observational and does not establish that reducing visceral fat will directly slow ageing, the authors argue the results support the case for targeting abdominal fat as part of broader strategies to promote healthier ageing in middle and later life.
For clinicians, the practical takeaway is that visceral fat may warrant attention even in people whose BMI or waist circumference appears unremarkable, and that the imaging tools needed to measure it are already widely available in routine care.
The study, “Visceral fat is associated with accelerated biological and cellular ageing,” is published in Obesity.
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