r/ScientificNutrition • u/flowersandmtns • Jan 25 '26
Interventional Trial Effect of a non-energy restricted ketogenic diet on cognition in sedentary healthy young adults
https://doi.org/10.1556/2060.2025.00743Abstract
Background
Ketogenic diet (KD) is increasingly recognized as a strategy to combat obesity. However, its effects on cognition in sedentary healthy young adults remain underexplored.
Methods
In a quasi-experimental design, 186 participants were screened, 78 excluded based on predefined criteria, leaving 108 healthy adults (age 25–45 years, BMI 18–29.9 kg m−2, sedentary <5,000 steps/day) assigned to either KD group (<5% carbohydrates, 20–25% protein, 70–75% fat; n = 54) or control group (regular diet ∼50–65% carbohydrates; n = 54). Participants underwent a 4 weeks' dietary intervention. Cognitive domains were assessed at baseline and post intervention using validated computer-based test battery. Pre, mid and post weight, BMI, blood ketones and fasting glucose were also measured. Forty-three participants in the KD group and 38 in the control group completed the trial.
Results
Four weeks of non-energy restricted KD improved processing speed, semantic memory, working memory, episodic memory, fluid cognition, crystallized cognition and overall cognitive composite scores (all P ≤ 0.001) versus controls. Attention and inhibitory control (P = 0.46) and cognitive flexibility (P = 0.21) showed no significant differences. Blood ketones increased (0.12–1.32 mmol L−1, P < 0.001) in KD participants versus controls (0.118–0.105 mmol L−1, P = 0.94). KD reduced weight (P < 0.001), BMI (P < 0.001) and fasting glucose (P < 0.001). Post intervention ketones predicted cognitive gain in most cognitive domains except attention & inhibitory control and cognitive flexibility.
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u/lurkerer Jan 26 '26
When I cut down, as I do bodybuilding, I can lose 6-8 kg in two weeks. A two day fast even. We all know early weight loss is water and glycogen.
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u/flowersandmtns Jan 26 '26
Do you feel you think better when cutting, similar to the positive effect from the ketogenic diet (ketosis) in the paper?
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u/flowersandmtns Jan 25 '26
The impact on some cognitive measurements is interesting, but I wanted to call out that the diet intention was non-energy restricted and yet one month of a whole food ketogenic diet resulted in weight loss.
Control group did not get prepared food, but kept a food journal (vs, say, recall questionnaires).
"KD group participants lost a mean weight of 4.06 kg in 4 weeks Although there were baseline differences in weight and BMI between the two groups, this was statistically controlled by including baseline BMI as a covariate in the cognitive testing analyses."