Study Shows This Is The Best Weight-Loss Diet For Liver & Blood Sugar Health

The promise behind nearly every weight-loss plan is that dropping about 10% of your bodyweight will improve your health across the board. And, while that is largely true, it assumes losing the pounds is what leads the change.

New research put that assumption to the test, specifically for people carrying obesity, prediabetes, and fatty liver disease. They compared three of the most popular diets, with participants in each group observing the diet until they hit the same weight-loss target. As expected, the metabolic payoff did not split evenly.

Inside the five-month trial

Researchers enrolled adults with metabolically unhealthy obesity, meaning they had excess weight alongside prediabetes and fatty liver disease. Participants were randomly assigned to one of three diets: a low-carb ketogenic diet, a Mediterranean diet, or a low-fat, plant-forward diet.

To make sure the results reflected the diets themselves rather than how well people stuck to them, researchers provided all of participants with food for about five months. That's a level of control you don't often see in nutrition research, where self-reported eating habits often muddy the results.

By the end of the study, all three groups had lost around 10% of their body weight. Having participants lose essentially equal amount of weight across groups allowed researchers to isolate the effects of each diet's macronutrient makeup, rather than the effects of weight loss itself.

Same weight loss, different liver outcomes

Participants saw similar improvements in how their muscles responded to insulin across all three diets. If the story ended there, the results would suggest that weight loss alone drives metabolic improvement.

But the liver told a different story. Participants in the keto group experienced a 2-3 times greater improvement in liver insulin sensitivity compared with the Mediterranean and low-fat groups. Liver fat dropped by 67% in the keto group, compared with 45% in the other two diets.

Prediabetes remission rates also differed dramatically by diet. 50% of participants in the keto group reversed their prediabetes, compared with 29% in the Mediterranean group and just 7% in the low-fat group.

The keto group also saw larger drops in key blood sugar markers, including hemoglobin A1c and fasting glucose and insulin levels.

What this means for your liver & blood sugar

These findings suggest that macronutrient composition, meaning the ratio of carbs, fat, and protein in your diet, can influence liver health and blood sugar control independently of weight loss. In other words, what you eat to lose weight may be just as important as how much weight you lose, especially when it comes to fatty liver and prediabetes.

Despite eating significantly more saturated fat, the keto group also maintained normal cholesterol numbers. LDL cholesterol, apoB, and 24-hour triglyceride levels were similar across all three diets. This means a higher-saturated-fat diet didn't automatically translate to higher cardiovascular risk, at least in this study's timeframe.

Keto isn't the "best diet" for everyone, and saturated fat doesn't get a blanket pass. The study focused specifically on people with metabolically unhealthy obesity over a defined period, so the findings may not generalize to everyone trying to lose weight or manage their health. But they do further our understanding of what drives insulin resistance more broadly, showing the picture is more nuanced than carbs versus fat alone.

How to use this if you're managing fatty liver or prediabetes

If you're navigating a fatty liver diagnosis, prediabetes, or insulin resistance, this research offers a few practical starting points:

The takeaway

This study is a reminder that weight loss isn't one-size-fits-all when it comes to metabolic health. For people with fatty liver disease and prediabetes, what you eat while losing weight can change how much your liver and blood sugar actually benefit.

If you're working on your metabolic health, talk to your doctor about which dietary approach best supports your specific goals.