What's the best diet for fatty liver disease? Here's what a new study found

A new randomised trial found every diet can help you lose weight. Only one of them made a real difference to your liver.

Today, researchers at Washington University School of Medicine published one of the more useful diet trials we've seen in a while. It didn't ask whether weight loss helps your metabolic health. We already know it does. It asked a more interesting question: does it matter which diet gets you there?

For anyone who has ever felt confused by competing diet advice, the answer is reassuring in one way and clarifying in another.

What the study did

Researchers randomly assigned 55 adults with obesity, prediabetes and fatty liver, a combination known as metabolically unhealthy obesity, to one of three diets for around five months: a low-carbohydrate, high-fat ketogenic diet, a high-carbohydrate, low-fat, plant-forward diet, or a Mediterranean diet in between. Every participant received 100% of their food for the study and met weekly with a dietitian, so this was about as tightly controlled as diet research gets. You can read the full study in Cell Metabolism here.

There is more to health than just weight loss

Across all three groups, participants lost about 10% of their starting weight, and muscle insulin sensitivity improved by roughly 50% from baseline, regardless of which diet they followed. The weight loss itself, not the specific mix of carbohydrates and fat, was what drove that improvement, but here's where it gets interesting! 

The clarifying part: your liver did not respond equally

This is where the three diets separated. Fatty liver disease affects around three in four adults with obesity worldwide, and it is now the fastest-growing cause of chronic liver disease. So how each diet affected the liver specifically matters a great deal. Here is what the researchers found.

1. Hepatic insulin sensitivity improved two to three times more on the ketogenic diet. Hepatic insulin sensitivity is a measure of how well your liver responds to insulin's signal to stop producing glucose. All three diets improved it. The ketogenic diet improved it two to three times more than the Mediterranean or high-carbohydrate diets.

2. Liver fat dropped by 67%, compared with 45% on the other diets. Fat stored inside the liver is one of the clearest drivers of insulin resistance and metabolic disease. On the ketogenic diet, it fell by roughly two-thirds. On the Mediterranean and high-carbohydrate diets, it fell by closer to half.

3. Twenty-four-hour blood glucose fell by 20%, compared with 8% on the other diets. Researchers tracked glucose continuously over 24 hours rather than relying on a single snapshot reading. The ketogenic group's blood sugar control improved substantially more than the other two groups.

4. Twenty-four-hour insulin levels fell by 74%, compared with 44% and 27%. This is the pancreas needing to work far less hard to manage blood sugar. Insulin levels dropped by 74% on the ketogenic diet, compared with 44% on the Mediterranean diet and 27% on the high-carbohydrate diet.

5. Half of the ketogenic group saw their prediabetes return to normal blood sugar levels. Fifty per cent of participants on the low-carbohydrate diet no longer met the criteria for prediabetes by the end of the study, compared with 29% on the Mediterranean diet and just 7% on the high-carbohydrate diet.

What this means for you

The senior author, Dr Samuel Klein, put it plainly: all three diets, despite very different macronutrient makeups, improved metabolic health through weight loss alone. That matters, because it means there is no single "right" diet for everyone, and no need to feel like you have failed if a particular plan was not sustainable for you.

But if you are carrying excess weight alongside fatty liver or prediabetes, this study is one of the clearest pieces of evidence yet that a low-carbohydrate approach does something extra for your liver and blood sugar that the other diets did not fully replicate. That aligns with exactly what we build into My Metabolic Action Plan: a structured, low carb approach to real food, alongside the skills and tools that make it sustainable rather than another diet you white-knuckle through and abandon.

Check out My Metabolic Action Plan here 

Dr Mary Barson and Dr Lucy are the founders of Real Life Medicine. They help women who have been on every diet under the sun, optimise their health and achieve long-lasting weight loss without feeling miserable or deprived.

They do this with their 3-step framework that

• Improves metabolism
• Develops mindset skills
• Provides tools to implement it easily into busy lives

With this comes increased energy, vitality and confidence.

You can avoid chronic disease and stop living life on the sidelines!

You can find out more about My Metabolic Action Plan here