A high-fat ketogenic weight loss program (KD) promotes higher total energy expenditure (TEE), which results in weight reduction. As well as, the appetite suppressant effects of acetoacetate (AcAc) and ketone bodies beta-hydroxybutyrate (BHB) promote weight reduction. A previous study revealed that 14 days of KD caused spontaneous weight reduction in obese and sort 2 diabetic patients. Nevertheless, there have been contradictory findings regarding the effect of a KD on TEE and appetite perception. 

Considering the contradictory results, a recent Clinical Nutrition ESPEN study compared the results of a one-day ketogenic weight loss program, fasting, and ketone salts (KS) supplementation with typical carbohydrates (CHO) on energy expenditure and appetite perception in healthy individuals.

Study: Impact of one-day fasting, ketogenic weight loss program or exogenous ketones on control of energy balance in healthy participants. Image Credit: Epine / Shutterstock

Background

Despite the fact that KD has many health advantages, including lowering glycemia and insulin levels, it has been related to some unwell effects, equivalent to a rise in low-density lipoprotein cholesterol. As well as, long-term adherence to KD might be difficult as a consequence of restricted food decisions and undesirable unintended effects, equivalent to gastrointestinal problems. Recently, intermittent fasting or short-term diets have gained much popularity.

Total fasting decreases energy expenditure (EE) and increases appetite. Due to this fact, 24 hours of KD might be a good weight loss program strategy to cut back weight. Currently, exogenous ketones (EXO) have turn out to be commercially available as racemic ketone salts (KS, D/L-BHB) or as ketone esters (KE, D-BHB), which might be used as supplements to realize ketosis.

There have been mixed results regarding appetite suppressant effects of exogenous ketone supplementation. For example, some studies revealed that KE mimics the appetite suppressant effect of a KD by decreasing the ghrelin levels. Nevertheless, others have contradicted this result and revealed that oral consumption or intravenous administration of KS doesn’t affect appetite suppression. 

Concerning the Study

A complete of 8 healthy adults, equally representative of men and ladies, were recruited into this randomized crossover study. All participants were 20 to 35 years old and had low to moderate regular physical activity. These participants were recruited from September 2020 to July 2021 on the University of Kiel, Germany.

All women needed to be on hormonal contraceptives to stop EE’s effects from the feminine cycle. As well as, participants with chronic diseases, pregnancy, alternative eating habits, food allergies, smoking, and high habitual physical activity, were excluded from this study. Finally, one participant was excluded from this study as a consequence of incorrect estimations linked to non-isocaloric energy intake with the ketogenic formula weight loss program (KETO).

Study Findings

In comparison with an isocaloric weight loss program with a standard CHO content, one-day isocaloric KD led to the next TEE and sleeping energy expenditure (SEE). Interestingly, the same effect was observed in a complete room indirect calorimeter (WRIC) study, which involved shifting from a standard 50% CHO-based weight loss program to an isocaloric KD with 5% CHO. SEE and TEE elevated by roughly þ100 kcal/ d with constant physical activity prescription and without alterations within the thermic effect of food (TEF).

Based on theoretical assumptions, a TEE of about 225 kcal/d was estimated as a consequence of the variations in CHO content between KETO and the isocaloric formula weight loss program (ISO). Nevertheless, such values weren’t achieved in the primary 24 hours of KD intervention. A modest increase of about 100 kcal/d was observed in response to a KD. This might be as a consequence of the rise in energy-demanding pathways, equivalent to hepatic gluconeogenesis (GNG) and the triglyceride fatty acid cycle.

In comparison with total fasting (FAST), a rise in cumulative EE was related to KETO intervention. This finding indicated that upregulation within the energy-demanding pathways occurs not before 16 hours of a ketogenic weight loss program. There was no difference in total N-excretion and cumulative CHO oxidation between FAST and KETO. The next EE with KETO might be attributed to an elevation in futile cycling of glucose and/or fatty acids as an alternative of only GNG. Because the protein content of KETO is lower in comparison with EXO and ISO, it caused lower TEF.

Here, one-day KD was found to be effective as a weight maintenance strategy. It is because it caused the next TEE, and ad libitum energy intake might be lower within the case of a habitual CHO-rich weight loss program (highly processed food). Nevertheless, these effects didn’t prevail when consuming a low-processed food weight loss program with a lower energy density. 

Notably, FAST was seen to reinforce GNG, ketogenesis, and ureagenesis. Due to this fact, resting energy expenditure (REE) was elevated during early fasting compared with ISO. Fasting was also linked with a rise within the sympathetic nervous system (SNS)-activity. Compared with ISO control, a discount in CHO oxidation was found with KS supplementation. Consistent with the present study’s findings, a previous study revealed that oral KS supplementation didn’t affect subjective appetite. The shortage of appetite suppressant effect might be because in the future of KD or fasting only causes a moderate increase in ketone levels.

Conclusions

The intra-individual cross-over design and the usage of a highly standardized setting of a WRIC are key strengths of this study. Nevertheless, the small sample size is the primary shortcoming of this study. The study found that a 24-hour ketogenic weight loss program increased energy expenditure and helped maintain a neutral balance of energy. Nevertheless, adding exogenous ketone bodies to an isocaloric weight loss program didn’t improve energy regulation. Subjective appetite rankings showed no differences between interventions.