Researchers have investigated the effects of fasting, ketone salt supplementation, and a one-day isocaloric ketogenic diet on the perception of appetite and energy expenditure in healthy people in a study that was published in the journal Clinical Nutrition ESPEN.
The appetite-suppressing properties of acetoacetate (AcAc) and beta-hydroxybutyrate (BHB) ketone bodies and a higher expenditure of energy may be possible explanations for the success of the ketogenic diet, which has a high fat and low carbohydrate content. Furthermore, patients with type 2 diabetes and obesity have reported spontaneous weight reduction after two weeks of implementing a ketogenic diet due to the low carbohydrate content of ketogenic diets, which also causes a decrease in insulin levels and glycemia.
However, the high-fat content of ketogenic diets has significant drawbacks, including an increase in low-density lipoprotein cholesterol and other health problems like gastrointestinal discomfort. In contrast, short-term diet options including a 24-hour ketogenic diet and intermittent fasting are preferable. Additionally, racemic ketone salts, which are exogenous ketones, have been utilized to induce ketosis recently.
Concerning the study
Eight adults between the ages of 25 and 30 with a body mass index (BMI) of 19 to 29 kilograms per square meter and habitual levels of physical activity ranging from low to normal were chosen for the study. Four men and four women, both of whom were continually using hormonal contraceptives to avoid the effects of the menstrual cycle on energy consumption, made up the study group.
The study excluded people who consumed alternative diets like veganism or vegetarianism, had chronic illnesses, or food allergies, were taking regular medications, smoked, experienced claustrophobia, was pregnant or nursing, engaged in vigorous physical activity, had lost more than 5 kg in the previous three months, or was currently on diets.
Air displacement plethysmography was performed to assess fat mass, which was then utilized to determine the fat mass index. Height and body weight were also recorded at baseline. The resting energy expenditure was calculated using indirect calorimetry. For 24 hours, four interventions—an isocaloric formula diet, complete fasting, an isocaloric ketogenic diet, and exogenous ketone salt supplements—were carried out, with the first and last four participants receiving each intervention in a different temporal order.
During three rounds of 20 minutes of exercise to maintain a physical activity level (PAL) of 1.65 during interventions, a bicycle ergometer was utilized to quantify work and energy. Before initiating the therapies, all participants received a regulated diet with a set composition of macronutrients to create equal baseline circumstances. The interventions and each person’s energy needs were measured using a whole-room indirect calorimeter.
Postprandially, blood and urine samples were collected at various intervals to measure the levels of BHB, AcAc, insulin, free fatty acids, C-peptide, and dopamine. At various intervals following a meal, assessments of appetite were also tested.
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The exogenous ketone supplement diet produced somewhat greater levels of ketones than the other three interventions, according to the results, while the total fasting and ketogenic diets produced much higher levels of ketone than the isocaloric formula diet. The ketogenic diet raised both energy expenditures, although the sleeping and overall energy expenditure did not differ between the isocaloric formula, total fasting, or exogenous ketone supplementation diets.
The exogenous ketone supplementation diet had a slightly lower rate of carbohydrate oxidation than the isocaloric formula diet, which led to a favorable carbohydrate balance. Additionally, the lack of an increase in energy expenditure with exogenous ketone supplementation demonstrated that switching the body’s metabolism from glucose to ketone use is impossible when both ketones and glucose are present.
The amplification of the triglyceride fatty acid cycle and hepatic gluconeogenesis, according to the researchers, could account for the ketogenic diet’s higher energy expenditure. The energy-demanding pathways only start to increase after roughly 16 hours of the ketogenic diet, according to comparisons of cumulative energy expenditure between the entire fasting and the ketogenic diets.
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Overall, the findings suggested that a 24-hour intermittent ketogenic diet might boost energy expenditure and support keeping an energy balance. Exogenous ketone salts added as supplements to an isocaloric diet do not, however, help to control the energy balance.