A research study published in Cell Reports Medicine in August 2024 was based on a Randomized Control Trial (RCT). Sixty healthy adult participants were randomized, and 53 participants completed up to 12 weeks of this intervention. The participants were grouped into:
1) moderate carbohydrate and moderate sugar diet (MODSUG)
2) restricted dietary free sugar diet (LOWSUG)
3) low carbohydrate and high-fat diet: Ketogenic diet (LOWCHO)
There were 18, 17 and 18 participants in the MODSUG, LOWSUG and LOWCHO groups respectively.
Baseline characteristics, habitual diet, physical activity energy expenditure (PAEE), biochemical profiles, diurnal glycemia, and muscle glycogen concentrations were measured and analyzed for this study. The study was conducted under almost complete free-living conditions, with only 3.5% of time spent within the laboratory
1) Body Fat: Low free-sugar or carbohydrate intake reduces body fat but not energy expenditure of the body. Both diets resulted in body fat loss but keto diet showed slightly better results in this area.
2) Gut Microbiome: Ketogenic diet alters gut microbial beta diversity but sugar restricted diet produced minimal effects on the gut bacteria.
3) Cholesterol: Low sugar diet reduces low-density lipoproteins(LDLs) but ketogenic diet increased atherogenic lipoprotein profile in four weeks.
4) Glucose Tolerance: Keto diet made the body less efficient at carbohydrate metabolism, resulting in reduced glucose tolerance.
Despite reducing fat mass, the ketogenic diet increased the levels of unfavorable fats in the blood of our participants, which, if sustained over years, could have long-term health implications such as increased risk of heart disease and stroke
Dr. Aaron Hengist, Lead Researcher, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Free Sugar Restriction:
Despite inducing an energy deficit and subsequent physiological feedback on appetite with dietary restriction of either free sugars or overall carbohydrates, there was no evidence of feedback on energy expenditure, including PAEE. Dietary free sugar restriction reduced fat mass (FM) and LDLs concentrations compared to control (MODSUG), but this was not accompanied by meaningful changes in postprandial metabolism.
Ketogenic Diet:
Popularly called as a 'keto diet' it comprises of a foods with a high fat content and a minimal carbohydrate content. This diet reduced body mass and FM compared to the control. It was also accompanied by more varied and divergent metabolic effects. Ketogenic carbohydrate restriction increased fat oxidation, transiently reduced both fasting and interstitial glucose concentrations, and transiently increased postprandial triglyceride concentrations. After 12 weeks of ketogenic carbohydrate restriction, there were substantial changes to the fecal microbial profile, insulin and energy signaling, and glucose transport protein levels in skeletal muscle and triglycerides.
These findings suggest that substantial fat loss can be achieved by restricting either free sugars or a ketogenic diet despite differences in how these diets affect whole-body and peripheral tissue metabolism. Whereas free sugar restriction had modest effects on whole-body or tissue-specific metabolism or the gut microbiome, ketogenic carbohydrate restriction had wide-ranging effects on metabolism, with sustained increases in whole-body and skeletal muscle fat oxidation, reductions in glucose tolerance, and alterations in gut microbial beta diversity.
This research suggests that keto diet may not necessarily produce a cardiometabolic health benefit that would be expected by the weight loss observed. Instead, free-sugar restriction may be a more appropriate dietary choice for overall cardiometabolic health for many people. Neither type of dietary restriction appears to meaningfully alter PAEE.
This new research study concludes that a low-sugar diet would be preferable for most people. More work is needed to understand how individuals may benefit from each type of diet. It is recommended that free sugars (those added to food or drink or found naturally in honey, syrups, fruit juices and smoothies) should be restricted to less than 5% of total energy intake. This research study is not meant for any treatment or diagnostic purposes. Kindly consult your physician for personal dietary recommendations.
References:
1) Aaron Hengist, Russell G. Davies, Jean-Philippe Walhin, Jariya Buniam, Lucy H. Merrell, Lucy Rogers, Louise Bradshaw, Alfonso Moreno-Cabañas, Peter J. Rogers, Jeff M. Brunstrom, Leanne Hodson, Luc J.C. van Loon, Wiley Barton, Ciara O’Donovan, Fiona Crispie, Orla O’Sullivan, Paul D. Cotter, Kathryn Proctor, James A. Betts, Françoise Koumanov, Dylan Thompson, Javier T. Gonzalez. Ketogenic diet but not free-sugar restriction alters glucose tolerance, lipid metabolism, peripheral tissue phenotype, and gut microbiome: RCT. Cell Reports Medicine, 2024; 101667 DOI: 10.1016/j.xcrm.2024.101667
2) Kohli, K. K., Kohli, K. K., & Dialogues, M. (2024b, August 14). Medical Dialogues. Medical Dialogues. https://medicaldialogues.in/diet-nutrition/news/ketogenic-diet-reduces-friendly-gut-bacteria-and-raises-cholesterol-levels-suggests-study-132977
3) Hengist, A., Davies, R. G., Walhin, J. P., Buniam, J., Merrell, L. H., Rogers, L., Bradshaw, L., Moreno-Cabañas, A., Rogers, P. J., Brunstrom, J. M., Hodson, L., Van Loon, L. J., Barton, W., O’Donovan, C., Crispie, F., O’Sullivan, O., Cotter, P. D., Proctor, K., Betts, J. A., . . . Gonzalez, J. T. (2024). Ketogenic diet but not free-sugar restriction alters glucose tolerance, lipid metabolism, peripheral tissue phenotype, and gut microbiome: RCT. Cell Reports Medicine, 101667. https://doi.org/10.1016/j.xcrm.2024.101667
(Input from various sources)
(Rehash/Dr. Shreya Dave/MSM)
