The Effects of a Ketogenic Diet and Exercise Interventions on Cognitive Function
Authors: Miutz Lauren Nicole , Baker Mark , Eason Alex , Gyorkos Amy 
Published: November 2023

Insulin resistance causes impaired glucose utilization and is a hallmark of Metabolic Syndrome (MetS) and Type II Diabetes. The human brain heavily relies on glucose as its primary fuel source requiring ~20% of total resting energy expenditure. Impaired glucose utilization may interfere with neuronal fuel supply and contribute to progressive nerve cell damage. The brain's cognitive‐critical areas are the most impacted, resulting in memory and cognitive deficits. An alternative and preferred fuel source for the brain are in the form of ketone bodies (KB). KBs support up to 60% of the metabolic needs of the brain and their delivery has been shown to be unaffected by insulin resistance, neuronal aging, and neurological diseases. KBs have also been explored as the potential key to stimulate growth factors that protect and nourish neuronal brain cells. The production of KBs can be induced naturally by exercise and feeding a high fat, low carbohydrate diet.

Purpose

The purpose of this study was to examine the effects of a short term Ketogenic diet with an exercise intervention on cognitive function in individuals characterized as having Metabolic Syndrome (MetS). Furthermore, to assess several aspects of cognitive function, including mental speed, flexibility, reasoning, concentration, thinking, and psychomotor ability.

Methods

Subjects (N=4) were instructed to follow a diet and exercise intervention for 4‐wk that preceded a 4‐wk washout period. Data was collected at baseline and following the 4‐wk intervention and washout periods. The diet consisted of unprocessed lean meat, fish, eggs, leafy and cruciferous vegetables, root vegetables, fruit, and nuts and devoid of cereal grains, dairy, beans, legumes, refined fats, bakery items, soft drinks, beer, extra salt and sugar. Foods such as nuts, dried fruit, potatoes (<1 medium‐sized per day) and wine (<1 glass per day) were recommended in limited amounts. The exercise intervention included high intensity interval training (HIIT), which consisted of a 3‐min warm‐up, 10 × 60 s cycling intervals interspersed with 60s of active recovery, and a 3‐min cool‐down for 4 total weeks. Cognitive function was measured with the smart phone Stroop Memory test application (Encephal) and MOS‐Cognitive Function Scale 6‐item survey (Optum).

Results

Compared to baseline, the intervention led to improvements in psychomotor speed and cognitive flexibility (13.7± 1.78 vs. 12.24 ± 2.05) and scores were reduced to near‐baseline values following the washout period (13.29 ± 1.45). Compared to baseline, subjects reported higher self‐perceived cognitive function following the intervention (80± 0.561 vs. 160 ± 0.583) and was reduced to near‐baseline levels (92 ± 0.592) following the washout period.

Conclusion

The diet and exercise interventions increased functional ketone bodies and cognitive function in individuals characterized as having MetS. The intervention improved one's ability to increase the speed of mental processing as well as the flexibility to transition from one concept to another. Diet and exercise may play an important role in providing an alternative fuel source to support cognitive‐critical areas of the brain, especially when suffering from impaired glucose utilization and insulin resistance.