A ketogenic diet produced a substantially greater reduction in liver fat than Mediterranean and low-fat, plant-forward diets in a new clinical trial involving people with obesity, prediabetes and fatty liver, researchers have found.
The study, published in Cell Metabolism on August 27, compared the effects of three eating plans after participants were guided to lose roughly 10 per cent of their body weight. Although all three diets improved muscle sensitivity to insulin, the keto group saw the strongest changes in liver metabolism and blood sugar control.
Among those following the ketogenic diet, liver fat fell by about 67 per cent, compared with approximately 45 per cent in each of the other groups. Liver insulin sensitivity also improved by two to three times as much as it did among participants on the Mediterranean or low-fat diets.
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The trial initially enrolled 55 adults, with results reported for 42 participants. The research team at Washington University School of Medicine supplied the food and provided weekly dietary support while adjusting calories to produce similar weight loss across the groups.
The ketogenic plan contained roughly 4 per cent of its calories from carbohydrates and 73 per cent from fat. By comparison, carbohydrates accounted for about half of the calories in the Mediterranean diet and around 70 per cent in the low-fat, mostly plant-based plan.
About half of the participants following the keto diet no longer met the criteria for prediabetes by the end of the study. The equivalent figures were 29 per cent among those on the Mediterranean diet and 7 per cent in the low-fat group.
Measures including glycated haemoglobin, insulin and round-the-clock blood glucose generally improved most in the ketogenic group. The reduction in liver fat was linked to a fall in the liver’s production of new fat.
However, the researchers stressed that the findings should be interpreted cautiously. The trial was small, lasted only several months and focused on a specific group of adults with obesity, prediabetes and excess liver fat, meaning the results may not apply broadly to the general population.
All three diets increased muscle insulin sensitivity by about 50 per cent, suggesting that weight loss itself produced important metabolic benefits regardless of the eating plan used.
Samuel Klein, the study’s corresponding author, said the results indicated that the composition of a diet could provide additional benefits beyond those associated with losing weight alone.
Registered dietitian Ilana Muhlstein said the findings were particularly relevant to people with prediabetes or fatty liver, but warned that a ketogenic diet may not be suitable as a long-term approach because of its typically high saturated-fat content and lower fibre intake.
She suggested that some people might discuss using keto as a short-term strategy with a healthcare professional before moving towards a Mediterranean-style diet, which is generally considered more favourable for long-term heart and overall health.
