Intestinal microbiota and obesity, the potential of the keto diet. Study

microbiota intestinale-obesità

A Chinese scientific study recently published on Nutrients (Wang et al., 2023) explores the alterations of the intestinal microbiota in subjects with obesity and the potential of the ketogenic diet (keto diet) as an intervention strategy. (1)

1) Globesity and weight reduction strategies

Obesity and overweight represent a public health problem at a global level, with an overall prevalence estimated at around two billion people, almost half of whom are obese. Globesity has a serious negative impact on:

– life expectation. Obesity is in fact associated with greater mortality from all causes; (2)

– life quality. In addition to serious and chronic diseases, NCDs (Non-Communicable Diseases, i.e. cardiovascular and neurological diseases, diabetes, tumors), there are various forms of disability and depression.

Current approaches to obesity mainly involve lifestyle interventions and dietary interventions are widely considered to be one of the most promising avenues for weight management. Although such interventions often produce short-term success, weight regain is almost inevitable. New weight management strategies are still in demand‘. (1)

2) Intestinal microbiota, obesity and diet

Current research demonstrated a substantial disparity in the composition of the gut microbiota between obese and normal-weight individuals and that the gut microbiome plays a crucial role in host energy metabolism. The human intestinal microbiota influences nutrient acquisition, energy expenditure and several metabolic pathways, thanks to a broad spectrum of metabolites‘. (1)

The alterations of the intestinal microbiota can modulate the effectiveness of dietary interventions, underlining the potential benefits of fine regulation of the intestinal microbiota. However, the extent to which different interventions impact the gut microbiota is varied, and research investigating the intricate interplay between dietary interventions, obesity, and the gut microbiota at the species level and microbial functional composition is still limited.‘. (1)

3) Intestinal microbiota, obesity and keto diet. The Chinese study

Researchers of Jiangnan University (China), department of food science and technology, collaborated with the Wuxi People’s Hospital of Nanjing Medical University and the Flanders Research Institute for Agriculture, Fisheries and Food (ILVO, Technology & Food Sciences) for:

– investigate the potential impact of a multiphase dietary protocol (multiphase dietary protocol), which incorporates an improved ketogenic diet (MDP-i-KD), on weight loss and on the intestinal microbiota, thanks to

– complete analysis, via metagenomic sequencing, of the taxonomic and functional composition of the intestinal microbiota of 13 participants before and after a 12-week MDP-i-KD intervention.

The microbiome of the recruited subjects – aged between 18 and 65, with BMI (Body Mass Index) > 28 kg/m2 and stable weight for three months – were also compared with that of normal weight individuals.

3.1) Ketogenic diet

The ketogenic diet– as seen (3) – induces a metabolic state of non-acidosis
pathological through the almost total elimination of carbohydrates from the diet. This state involves the use of the glucose necessary for the body, present in adipocytes as glycerol, together with fatty acids. That is to say that the body, in lack of glucose from external sources, uses the fat present in its adipose tissues.

The energy supply in the keto diet is not reduced in the initial phase, but is distributed according to a criterion that favors proteins (1-1,5 g/kg of body weight) and lipids, with additional contributions of Omega-3 fatty acids, potassium citrate, vitamins and minerals. Carbohydrates are eliminated in the first phase, to be gradually reintroduced in the subsequent two where physical exercise and low-calorie regimes are introduced. (3)

This type of diet must be followed under medical supervision which includes the evaluation of urinary ketones, to be measured every three days. The keto diet works – as also recognized by the Ministry of Health in Italy, in a specific study (4) – but requires a great individual commitment over several months which for many is not easy to maintain, after having obtained significant provisional results.

3.2) Multiphase dietary protocol with improved ketogenic diet (MDP-i-KD)

The protocol multiphase diet supplemented with an enhanced ketogenic diet (MDP—i m-KD) used in the current study (Wang et al., 2023) was structured as follows:

– hypocaloric balanced diet (HBD) for an initial period of 4 weeks

– subsequent intervention of alternating cycles of 2 weeks of keto diet followed by 2 weeks of transition diet with carbohydrates (in the first cycle) or balanced low-calorie diet (in the two subsequent cycles), for 12 subsequent weeks.

4) Provisional conclusions

The application of the MDP—i m-KD protocol, after 12 weeks of treatment, induced a significant decrease in body weight (9,4% on average) compared to the period before the intervention. Significant reductions were thus recorded in Body Mass Index, waist size, hip, blood pressure, liver (AST, ALT, tryglicerides) and pancreas (HbA1c) health indicators. The concentrations of total cholesterol and LDL cholesterol did not vary significantly significant, while the concentration of HDL cholesterol (so-called good cholesterol) increased.

The analysis of taxa and functional groups of microbes also revealed ‘a shift in interactions, in the gut microbiota, towards a healthier state after weight loss, characterized by positive associations between species linked to weight loss and inhibitory relationships between species associated with obesity after the intervention‘. This work provides insights for developing new microbiome-based weight management interventions, and further research is therefore needed to delve deeper into the biological mechanisms of interaction of various strains with the metabolic system.

Dario Dongo and Adele Fantoni


(1) Wang, Hongchao, Xinchen Lv, Sijia Zhao, Weiwei Yuan, Qunyan Zhou, Faizan Ahmed Sadiq, Jianxin Zhao, Wenwei Lu, and Wenjun Wu (2023). Weight Loss Promotion in Individuals with Obesity through Gut Microbiota Alterations with a Multiphase Modified Ketogenic Diet. Nutrients 15, no. 19:4163.

(2) GBD 2015 Obesity Collaborators. Afshin et al. (2017). Health Effects of Overweight and Obesity in 195 Countries over 25 Years. N Engl J Med. Jul 6;377(1):13-27. doi: 10.1056 / NEJMoa1614362

(3) Adele Fantoni. Keto diet and very low carb diet, the ABCGIFT (Great Italian Food Trade). 12.8.22

(4) Marta Strinati. High-protein diet and ketogenic diet, strengths and limitsGIFT (Great Italian Food Trade). 5.12.21

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Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.

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Surgeon Specialist in dentistry, orthodontics, nutritionist and aesthetic doctor


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