Nutritional quality through analysis of the foods chosen and consumed Buffet items are classified (pre-defined classification) into seven groups based on their macronutrient content and energy density: starchy foods, meat and fish, fruits and vegetables, dairy products, sweet desserts, sauces, and sweetened beverages. They are also classified according to their fat, sugar, and protein content, and their energy density (4 groups).

The quantities consumed in grams and as a percentage of energy intake per group will be assessed for each subject and per visit.

time spent selecting food at the buffet, duration of ingestion, ingestion speed, total meal duration, number of bites per minute, total number of bites and bites by food type, and food choices

Several indicators will be assessed for the buffet's microstructure based on the analysis of videos taken during the buffet:

- Buffet time

time spent selecting food at the buffet, duration of ingestion, ingestion speed, total meal duration, number of bites per minute, total number of bites and bites by food type, and food choices Assessed with visual analog scale from 1(worse outcome) to 10 (better outcome)

binge eating using sub-scores from tthe BES (Binge Eating Scale) for binge eating

BES : Binge Eating Scale - score from 0 to 46, score of 46 = highest level of binge eating disorder

Food preferences using the short version of the LFPQ (Leeds Food Preference Questionnaire) LFPQ : Leeds Food and Preference Questionnaire- score from 0 to 100 on preference or motivation for a type of food, high score = strong preference or motivation

Assessed using visual analog scales rated from 0 (worse outcome) to 10 (better outcome) on the following dimensions : hunger

Assessed using visual analog scales rated rom 0 (worse outcome) to 10 (better outcome) on the following dimensions : feeling of satiety

Assessed using visual analog scales rated from 0 (worse outcome) to 10 (better outcome) on the following dimensions : desire to eat

Assessed using visual analog scales rated from 0 (worse outcome) to 10 (better outcome) on the following dimensions : consommation

Assessed using visual analog scales rated rom 0 (worse outcome) to 10 (better outcome) on the following dimensions : meal appreciation

Assessed using Taste Strips tests

Assessed using Taste Strips tests

Assessed using Taste Strips tests

Assessed using Taste Strips tests

Assessed using Taste Strips tests

Assessed using dedicated questions

Assessed using the BAQ questionnaire (Body Awareness Questionnaire) BAQ : Body Awarness Questionnaire - score from 13 to 65, score of 65 = positive assessment of one's body

Assessed using visual analog scales rated from 0 to 10 on the following dimensions: desire to eat

Assessed using visual analog scales rated from 0 to 10 on the following dimensions

Evaluated via gene function analysis from metagenomics data, metabolomics and short-chain fatty acid quantification

Evaluated via gene function analysis from metagenomics data, metabolomics and short-chain fatty acid quantification

Blood sample to measure :

Adiponectin µg/ml

Assessed by volatolomic signatures

BMI will be assessed

Energy metabolism by indirect calorimetry

postprandial plasma markers: We will assess: glycaemia (g/L)

CRP

Blood pressure

Blood vitamin status :

For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable).

The vitamins assessed are :

- Vitamin B12 (pmol/L) should be above 145 pmol/L

Blood mineral status:

• Calcium (mmol/L) should be above 64 mmol/L
• Phosphor (mmol/L) should be above 0.81 mmol/L
• Magnesium (mmol/L) should be above 0.66 mmol/L
• Sodium (mmol/L) should be above 136 mmol/L
• Potassium (mmol/L) should be above 3.4 mmol/L
• Chlore (mmol/L) should be above 98 mmol/L

Plasma fatty acid profile

Protein status

Assessed using 3-day dietary recall randomly selected from the 7 days preceding the visits

Assessed using 3-day dietary recall randomly selected from the 7 days preceding the visits

Assessed using 3-day dietary recall randomly selected from the 7 days preceding the visits

Quality of life using the SF36 questionnaire SF36 - health status questionnaire - score from 0 to 100, score of 100 = excellent perceived health

Self-confidence and self-efficacy using the GSES GSES: Generalized Self-Efficacy Scale - score of 10 to 40, score of 40 = strong confidence in one's ability to effectively manage different life situations and challenges

Depression with PHQ-9 PHQ-9: Patient Health Questionnaire

-score from 0 to 27, score of 27=severe depression

Anxiety assessment using GAD-7 GAD-7: Generalized Anxiety Disorder - if score >7 then anxiety disorders should be suspected

Assessed using the short version of the IPAQ IPAQ: International Physical Activity Questionnaire - continuous daily energy expenditure score, high score means high AP

The questionnaire allows the subject to be classified according to 3 levels of activity: inactive, moderate, high.

positive and negative emotion assessed using the PANAS scale PANAS: Positive Affectivity and Negative Affectivity Scale - 2 scores from 10 to 50 - positive affectivity score = 50 best, negative affectivity score = 50 worst

food phobias using the FNS questionnaire FNS : Food Neophobia Scale -score from 10 to 70 - score of 70 = neophobia, i.e. less willingness to try new foods

loneliness using the ESUL questionnaire University of Laval Loneliness Scale - score from 20 to 80, score of 80 = most pronounced feeling of loneliness

Assessed using Bristol stool scale Bristol scale : 7 types of stools to choose from photo: type 1 = hard and lumpy stools, type 7 = completely liquid stools

Assessed using Bristol stool scale : 7 types of stools to choose from photo: type 1 = hard and lumpy stools, type 7 = completely liquid stools

Assessed using Bristol stool scale

Evaluation by FibroScan® but only for patients who had a FibroScan® performed before surgery.

Evaluation by FibroScan® but only for patients who had a FibroScan® performed before surgery.

Behaviors (emotional eating and cognitive restraint) using score from the DEBQ (Dutch Eating Behavior Questionnaire) a DEBQ : Dutch Eating Behaviour Questionnaire : 3 sub-scores: cognitive restriction, reactivity to external stimuli and emotionality from 1 to 5, score 5 = strong impact of eating behavior

Assessed via the degree of alteration of MAMs (Mitochondia-Associated Membranes) in peripheral blood mononuclear cells (PBMCs), only for patients who had a FibroScan® performed before surgery.

thyroid function: Thyroid function is assessed based on TSH levels in mIU/L (should be above 0.4 mIU/L and below 4.8 mIU/L), 2.

The assessment for the research is whether the measures are within the limits or not (yes/no variable).

Based on the three 24-hour reminders completed by participants before each visit, the dietitian will classify participants into three categories: good, average or poor compliance.

time spent selecting food at the buffet

duration of ingestion

ingestion speed

Assessed using Likert scale Likert scale : 7 types of stools to choose from photo: type 1 = hard and lumpy stools, type 7 = completely liquid stools

Assessed using gastrointestinal symptoms using GSRS Gastrointestinal Symptom Questionnaire - score 15 to 105, score 105=severe gastrointestinal symptoms

complete blood count

AST

ALT

gamma GT

bilirubin

alkaline phosphate

creatinine

uric acid

ionogram results: Sodium (mmol/L) which should be between 136 and 145 Potassium (mmol/L) which should be between 3.4 and 4.5 Chlorine (mmol/L) which should be between 98 and 107 Bicarbonates (mmol/L) which should be between 22 and 29

coagulation : prothrombin time

Assessed using Likert scale

Assessed using gastrointestinal symptoms using GSRS : 15 questions with answers from No discomfort at all at Very severe discomfort (7 levels)

Assessed using Likert scale

gastrointestinal symptoms using GSRS

total meal duration

number of bites per minute

total number of bites

bites by food type

food choices

Calorie intake consumed per minute of the buffet

ionogram results:

Anion gap = (Na+ + K+) - (HCO3- + Cl-) (mmol/L) which should be between 12 and 20

Blood sample to measure :

Ghrelin pg/ml acylated ghrelin pg/ml

Blood sample to measure :

GIP pmol/l total GLP-1 : pmol/L glucagon : pmol/L

Blood sample to measure :

total PYY : ng/L

Blood sample to measure :

leptin : ng/ml

We will assess: insulin (mU/L)

We will assess: triglycerides (mmol/L), HDL (mmol/L), LDL (mmol/L), ApoB (mmol/L), sphingolipid (mmol/L) and unesterified fatty acid(mmol/L)

we will calculate: HOMA-IR (=insulin*glycarmia/22.5) and the total cholesterol/HDL cholesterol ratio.

postprandial plasma markers: We will assess: insulin (mU/L)

Blood vitamin status :

For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable).

The vitamins assessed are :

- Vitamin B9 (mmol/L) should be above 10.4 mmol/L

Blood vitamin status :

For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable).

The vitamins assessed are :

- Vitamin B1 (nmol/L) should be above 78 nmol/L

Blood vitamin status :

For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable).

The vitamins assessed are :

• Vitamin C (µmol/L) should be above 25 µmol/L
• Vitamin A (µmol/L) should be above 1.40 µmol/L

Blood mineral status:

• Iron (µmol/L) should be above 5.8µmol/L
• Selenium (µmol/L) should be above 56µmol/L
• Zinc (µmol/L) should be above 9.20µmol/L

thyroid function: Thyroid function is assessed based on free thyroxine in pmol/L (should be above 11.9 pmol/L and below 21.9 pmol/L)

The assessment for the research is whether the measures are within the limits or not (yes/no variable).

thyroid function: Thyroid function is assessed based on free triiodothyronine in pmol/L (should be above 3.1 pmol/L and below 6.8 pmol/L).

The assessment for the research is whether the three measures are within the limits or not (yes/no variable).

Waist-to-hip ratio will be assessed

resting heart rate

coagulation : activated partial thromboplastin time

coagulation : fibrinogen

We will assess: total cholesterol (g/L)

We will assess: HbA1c (mmol/mol),