Keto, Liver Fat, and a More Nuanced Message About Dietary Fat

A recent randomized pilot study adds an important—and encouraging—piece of evidence to the growing case against treating dietary fat as the enemy.

In adults with overweight or obesity and metabolic dysfunction-associated steatotic liver disease (MASLD), a 12-week ketogenic very-low-energy diet produced substantially greater weight loss and a much larger reduction in liver fat than a prescribed Mediterranean-style diet. The results do not mean that one diet is ideal for every person. They do, however, strengthen the view that carbohydrate restriction and nutritional ketosis can be powerful therapeutic tools for selected people with obesity, insulin resistance, and fatty liver.

This is highly consistent with the central message of Beyond the Fear: The Truth About Fats and Your Health: fats are essential biological nutrients, not inherently harmful substances. The relevant questions are not simply whether a diet contains fat. They are which fats are consumed, what foods replace refined carbohydrates, whether the overall dietary pattern improves metabolic regulation, and whether the approach can be sustained by the individual.

What the Study Found

The study enrolled 25 adults with biopsy-confirmed MASLD and randomly assigned them to either a ketogenic very-low-energy diet or a Mediterranean-style diet for 12 weeks.

The ketogenic intervention was not merely a generic “high-fat diet.” It was a structured, low-carbohydrate, very-low-energy, meal-replacement-based program intended to induce nutritional ketosis and promote substantial weight reduction. After the initial phase, participants entered a maintenance period that included low-dose semaglutide.

At 12 weeks, participants in the ketogenic group lost approximately 13% of their starting body weight, compared with approximately 4% in the Mediterranean-diet group. Liver fat, measured by MRI, fell by about 77% in the ketogenic group, compared with approximately 14% in the Mediterranean group. In addition, 69% of participants in the ketogenic group reached a normal range of liver-fat content.

These are clinically meaningful changes. Excess fat stored in the liver is not merely an imaging finding. It is closely linked with insulin resistance, type 2 diabetes, elevated triglycerides, systemic inflammation, and progression from simple steatosis to steatohepatitis, fibrosis, cirrhosis, and, in some people, liver cancer.

Weight loss remains one of the most effective approaches to MASLD. Even moderate weight reduction can improve liver fat and metabolic markers. Greater and sustained loss of body weight can improve liver inflammation and, in some cases, fibrosis. The magnitude of weight loss achieved in this ketogenic intervention is therefore especially relevant.

Why a Ketogenic Approach May Help

A ketogenic diet sharply reduces carbohydrate intake, particularly sugars, refined grains, starchy foods, and many ultra-processed products. When carbohydrate availability falls sufficiently, insulin levels generally decline, the body increases its use of stored fat for energy, and the liver produces ketone bodies that can be used as fuel by many tissues.

For people with insulin resistance and fatty liver, this metabolic shift may be helpful for several reasons.

• Lower exposure to added sugars and refined starches can reduce repeated glucose and insulin surges.
• Reduced insulin signaling may lessen the tendency to store energy as fat and may facilitate release of stored fat from adipose tissue.
• Carbohydrate restriction may reduce hepatic de novo lipogenesis—the conversion of excess carbohydrate into fat within the liver.
• Higher-fat and adequately protein-containing meals may improve satiety for some people, making it easier to reduce total energy intake without persistent hunger.
• Weight loss itself reduces visceral adiposity and the delivery of fatty acids and inflammatory signals to the liver.

The ketogenic group in this study achieved all of these changes in a highly structured manner. The intervention combined carbohydrate restriction with a marked energy deficit and rapid weight loss. It is therefore best understood as a comprehensive metabolic strategy rather than evidence that fat alone is responsible for the outcome.

That distinction matters. Dietary fat should not automatically be blamed as the primary dietary cause of fatty liver. MASLD develops through a complex interaction among excess energy intake, insulin resistance, visceral adiposity, genetic susceptibility, physical inactivity, dietary pattern, and food quality. For many people, added sugars, refined carbohydrates, and ultra-processed foods may play a more important role than the presence of natural fats in foods such as fish, eggs, nuts, seeds, olives, avocados, and olive oil.

Interpreting the Findings in Context

This was a small pilot trial, but it should be regarded as an important addition to a wider body of supportive evidence—not as an isolated result.

Low-carbohydrate and ketogenic dietary approaches have repeatedly been associated with improvements in body weight, waist circumference, triglycerides, glycemic control, insulin resistance, and visceral adiposity. In people with obesity and fatty liver, studies increasingly suggest that carbohydrate restriction may reduce liver fat relatively quickly, especially when it is accompanied by meaningful weight loss.

The present findings are particularly notable because liver fat was measured by MRI rather than inferred only from liver enzymes or body weight. The magnitude of the reduction in liver fat—77% in the ketogenic group—suggests that an intensive ketogenic approach can be especially useful when rapid reduction of liver fat is an important clinical goal.

The study also illustrates that not all ketogenic diets are alike. A carefully designed program can differ greatly from a casual, self-directed “keto” diet built around processed meats, large quantities of butter, cream, cheese, or commercially marketed keto snacks. The quality of food, adequacy of protein, micronutrient intake, fiber, food preferences, and the ability to maintain the approach all influence both safety and long-term success.

The important message is not that ketogenic nutrition must replace Mediterranean eating or every other healthy dietary pattern. Mediterranean-style diets have substantial evidence supporting cardiometabolic health and can be highly beneficial for many people. Rather, the study suggests that a ketogenic very-low-energy strategy may be a particularly effective option for selected individuals who need more intensive early treatment for obesity, insulin resistance, or MASLD.

What Requires Attention

Because the ketogenic intervention supplied fewer calories than the comparison diet, it is not possible to attribute every benefit exclusively to ketosis. A major energy deficit and greater weight loss almost certainly contributed to the favorable changes in liver fat and metabolic health.

This is not a weakness that invalidates the intervention. In clinical care, successful treatment often works through several mechanisms at once. If a person can safely reduce carbohydrate exposure, improve satiety, achieve a meaningful energy deficit, and lose harmful visceral and liver fat, the combined effect may be exactly what is needed.

The later 24-week outcomes should also be interpreted as results of a combined strategy because the ketogenic group received semaglutide during the maintenance phase. Semaglutide can support appetite regulation and weight-loss maintenance, so the longer-term findings cannot be attributed to diet alone.

Another point deserves practical attention: preservation of lean mass. The ketogenic group lost lean mass along with fat mass, with lean mass representing approximately one-quarter of total weight lost at 12 weeks. Some lean-tissue loss occurs with most substantial weight-loss programs, especially when weight falls rapidly. However, it should never be ignored.

Adequate protein intake, resistance exercise when medically appropriate, regular physical activity, and attention to strength and functional capacity should be integral parts of intensive weight-loss treatment. These safeguards are particularly important for older adults and for people with frailty, sarcopenia, low muscle mass, chronic illness, or reduced mobility.

The goal is not simply to make the number on the scale smaller. The goal is to reduce harmful liver and visceral fat while preserving muscle, strength, mobility, and long-term health.

A Practical Keto-Oriented Message

For people with obesity-related fatty liver and metabolic dysfunction, reducing intake of added sugars, refined starches, sweetened beverages, and ultra-processed foods can be an effective first step. A ketogenic or lower-carbohydrate dietary approach may be especially useful for people who have insulin resistance, elevated triglycerides, type 2 diabetes, central obesity, or fatty liver—and who find that carbohydrate restriction improves their hunger control and dietary adherence.

A well-formulated ketogenic diet should emphasize food quality rather than simply high fat intake. It can include:

• Olive oil, olives, avocados, nuts, and seeds.
• Fish and seafood, including oily fish rich in omega-3 fatty acids.
• Eggs, poultry, and other appropriate protein sources.
• Non-starchy vegetables, herbs, spices, and fiber-containing plant foods within the individual’s carbohydrate tolerance.
• Plain yogurt, fermented foods, and selected dairy foods when tolerated and compatible with the individual’s health goals.
• Water, unsweetened tea, coffee without added sugar, and other non-sugar-sweetened beverages.

At the same time, it is sensible to limit industrial trans fats, highly processed foods, sugar-sweetened drinks, refined grains, excessive alcohol, and heavily marketed “keto” products that may be low in nutritional quality despite their low carbohydrate content.

The aim is not to create fear of carbohydrate in the same way that earlier dietary messages created fear of fat. Carbohydrate requirements and tolerance vary widely. Some people thrive with moderate carbohydrate intake based on minimally processed foods, legumes, fruits, vegetables, and whole grains. Others, especially those with obesity, insulin resistance, type 2 diabetes, or MASLD, may obtain meaningful benefits from a more substantial reduction in carbohydrate intake.

Moving Beyond Fear of Fat

The deeper lesson of this study is not simply that keto can reduce liver fat. It is that nutrition should not be governed by simplistic slogans.

“Fat makes you fat” is no more useful than “carbohydrates are always harmful.” Both statements ignore biology, food quality, metabolic context, energy balance, physical activity, genetics, medications, and individual response.

Dietary fat is indispensable to human physiology. It contributes to cell membranes, nerve insulation, hormone synthesis, energy storage, absorption of vitamins A, D, E, and K, inflammatory signaling, and many other biological processes. The right response to dietary fat is not fear. It is discernment.

For selected people with obesity-related fatty liver and metabolic dysfunction, ketogenic nutrition can be a powerful therapeutic option. It may help reduce carbohydrate-driven insulin exposure, mobilize stored fat, improve satiety, lower triglycerides, reduce liver fat, and initiate meaningful weight loss.

But it should be applied thoughtfully. The best dietary pattern is the one that improves metabolic health, preserves muscle and function, supports cardiovascular risk reduction, fits the person’s medical condition and preferences, and can be maintained over time.

A ketogenic diet is therefore best understood not as a universal ideology, but as one valuable tool in modern metabolic medicine. It can help us move beyond an outdated fear of fat and toward a more mature question: which combination of foods, nutrients, and lifestyle practices will help this particular person live with less disease, greater strength, and better health?

More about this topic can be found in our book "Beyond the Fear: The Truth About Diet Fats and Your Healt" on Our Books on Google Play.

Mykola Iabluchanskyi together with Andriy Yabluchanskiy