The objective of the study is to analyze the specific role of physical properties of food and mastication in the cephalic phase reflex of thermogenesis, and the involvement of the autonomic nervous system in the implementation of this reflex. The hypothesis of the study is that oral stimulation elicited by food properties during mastication can generate changes in the amplitude of variation of thermogenesis, and that these changes are distinct from those attributable to the thermal effect of food during digestion.
A group of 12 subjects presenting a normal weight and a group of 12 obese subjects, with a good general health and a good dental state will be constituted. They will participate to 5 different recording sessions during which they will be invited to chew and spit out foods and chewing gums of different hardness. During recording sessions with mastication and no-mastication periods, gas exchange (O2 concentration), cardiac activity (electrocardiography) and muscular activity of masticatory muscles (electromyography) will be recorded. Blood samples will be collected during one of the sessions to analyse the kinetic of appearance of some hormones in the blood compartment during or just after mastication. The selected hormones are involved in the eating behaviour and its regulation (ghrelin, peptide C, peptide YY and glucose-like peptide 1). From these recordings, energy expenditure, heart rate variability, intensity of masticatory muscle contraction, and hormone blood appearance will be analysed in link with the nature and hardness of the food chewed. Since the food bolus is spit out after mastication (without any swallowing = sham-feeding), the changes observed in theses variables will be directly attributed to sensory information coming from oral cavity during mastication. Food choice and sport activity of each volunteer will be taken into account to compare the results obtained for the two groups (normal weight and obese). The work will produce more data and evidence on the contribution of oral signals attributable to the food in the regulation of the energy balance. The results will also bring more knowledge on the involvement of the autonomic nervous system. Comparison of the results obtained for the two groups (normal weight and obese people), will bring some positive outcomes which could be useful in the fight against obesity.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Simultaneous recordings of postprandial thermogenesis (gas exchange), cardiac activity (ECG), masticatory muscle contraction (EMG), and blood collection, during alternating periods of no-mastication or mastication of natural foods or chewing gums of different hardness
CHU de Clermont-Ferrand
Clermont-Ferrand, Auvergne, France
RECRUITINGMeasure of energy expenditure by Indirect calorimetry
effect of mastication without swallowing on energy expenditure (kcal/24h) in normal weight and obese people. This will be measured by indirect calorimetry (Under Canopy of the system Fitmate)
Time frame: 1 hour 30 minutes
Measure of cardiac activity
effect of mastication without swallowing on cardiac activity (R-R interval) in normal weight and obese people measured by electrocardiogram
Time frame: 1 hour 30 minutes
Measure of masticatory muscle activity
effect of mastication without swallowing on masticatory muscle activity (microvolt.s in normal weight and obese people measured by electromyography
Time frame: 1 hour 30 minutes
Estimate of the hormonal response
effect of mastication without swallowing on hormonal response in normal weight and obese people. This will be estimate by their concentration and their kinetic of appearance in the blood compartment, and by comparisons of concentration values with basal level, also expressed in "area under the curve" values.
Time frame: 1 hour 30 minutes
effect of sensory information from oral cavity on energy expenditure by Indirect calorimetry
effect of various oral information coming from oral cavity during mastication (food hardness, type of food…) on energy expenditure (kcal/24h) in normal weight and obese people. This will be measured by indirect calorimetry (Under Canopy of the system Fitmate)
Time frame: 1 hour 30 minutes
effect of sensory information from oral cavity on cardiac activity
effect of various oral information coming from oral cavity during mastication (food hardness, type of food…) on cardiac activity (R-R interval) in normal weight and obese people. This will be measured by electrocardiogram.
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Purpose
PREVENTION
Masking
NONE
Enrollment
24
Time frame: 1 hour 30 minutes
effect of sensory information from oral cavity on hormonal response
effect of various oral information coming from oral cavity during mastication (food hardness, type of food…) on hormonal response in normal weight and obese people. This will be estimate by their concentration and their kinetic of appearance in the blood compartment, and by comparisons of concentration values with basal level, also expressed in "area under the curve" values.
Time frame: 1 hour 30 minutes
effect of sensory information from oral cavity on masticatory muscle activity
effect of various oral information coming from oral cavity during mastication (food hardness, type of food…) on masticatory muscle activity (microvolt.s) in normal weight and obese people. This will be measured by electromyography
Time frame: 1 hour 30 minutes
cardiac activity while sleeping measured by electrocardiogram
evaluation of the general tonus of the autonomic nervous system in normal weight and obese people (R-R interval measured by electrocardiogram)
Time frame: 8-10 hours (night)
cardiac activity (frequency analysis) while sleeping measured by electrocardiogram
evaluation of the general tonus of the autonomic nervous system in normal weight and obese people
Time frame: 8-10 hours (night)
global characterization of sport activity
evaluation of the mean energy expenditure in link with physical activity (kcal/time unit) to have a global characterization of the volunteer. This will be done by the app WellBeNet wich contains eMouv for sport activities.
Time frame: 4 consecutive days
global characterization of food choices
evaluation of the mean energy expenditure in link with food choices and food habits (food portion, score), to have a global characterization of the volunteer. This will be done by the app WellBeNet wich contains NutriQuantic for food choices
Time frame: 4 consecutive days